Serde enum flatten However, be warned that if the enum variant isn't unique and can't be clearly identified from the JSON, then it From kubernetes documentation, a variant on serde's adjacently tagged enums can be found: metrics: - type: Resource resource: name: cpu targetAverageUtilization: 50 - type: Pods pods: metricName: packets-per-second targetAverageValue: 1k [^serde-restrictions]: Most of these restrictions are currently blocked on serde#1183, which limits non-self-describing formats from roundtripping format-specific information through internally (or adjacently) tagged or untagged enums or #[serde(flatten)]ed fields. I'd love to be able to use serde to deserialize a string such as "X1" or "Y3", and automatically get back a Main::A(SubA::X1) or Main::B(SubB::Y3), respectively. Here are the conventions selected by the serde_json data format. The idea of this crate is that you can use the serde system to implement FromStr or Display for your own types based on the how serde would handle the type. #[serde(bound = "T: MyTrait With the serde-compat feature (enabled by default), serde attributes can be parsed for enums and structs. The issue that I am having is that the csv file has some junk at the front, so I need trim that off before I JSON doesn’t include the concept of enums, but that’s OK because serde is flexible enough to massage these data types into a JSON equivalent. Hello community! I am new to rust and am currently learning about the "serde" framework. Only when derive is not getting the job done. Error: thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Error("invalid type: integer `20`, expected struct Helper macro when implementing the Deserializer part of a new data format for Serde. Suppose we have an array of integers and we want to figure out the maximum value without holding the whole array in memory all at once. The results may be interesting for diagnosis: With #[serde(untagged)]. However, when deserializing, I don't know how to handle "flux_type" as the marker of "this is actually a FluxDensityType (and vice versa when serializing). execute() to return the proxy struct (correct me if I'm wrong). It works great, and is super convenient. Getting help. As we work with HTTP Requests, we always need to convert back and forth between a data structure, it can be enum, struct, and etc. Actually, I'm not right here. The &s are at some level just fancy pointers, and pointers get decided by your allocator or stack depth at runtime, they can't be already contained in the data you're deserializing (ignoring insane mmap hacks). To accomplish that, we need to use our first serde attribute Enums taking a single value can use the flatten field attribute in order to be inferred from their variant key directly: #[derive(Debug, PartialEq, Deserialize)] #[serde(rename_all= "kebab-case" )] enum Mode { // Work with a local file. It's probably not Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company Visit the blog Use #[serde(rename = "name")] to change the string used for the enum variant when serializing and deserializing. The placeholder type _ marks all the places where the type’s Serialize implementation should be used. In a language like go this would be struct composition but here I tried serde flatten and it worked fine. For example, bool in serde corresponds to the boolean type in Rust. Reply ar-pharazon • Additional comment actions. Currently, we're actually using a dynamic translation by first serializing the struct to a serde_json::Value, then Structs and enums in JSON. As my code will certainly survive for at least another 7,999 years, this gives me quite a lot of relief. The answer was to use serde's flatten macro for the file_or_folder that did not exist in the raw data, but was built using a combination of fields in the raw data (per the serde docs for Pagination, where the raw data does not have the key pagination, but the values to construct Pagination). To parse the rest of the result object, you can just parse everything into an HashMap. Serde is one of the most widely used Rust libraries so any place that Rustaceans congregate will be able to help you out. #[derive(Deserialize)] struct GameData { #[serde(flatten)] player Side note: representing the datastore value the following way may be more convenient. Stack Overflow. To answer your question directly: No, there is no attribute in serde which You signed in with another tab or window. I am still learning Rust and Serde so this is both a help and code review request. Find and fix vulnerabilities Actions. You can use Options::with_fixint_encoding to encode integers with the same precision as their Rust type, but you don't need to specify it, as it is the default already. You signed in with another tab or window. Unfortunately, since I am serializing this code for consumption by another service (not controlled by me), I'm not so sure that their deserialization will be as conformant to the spec. The default Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. Asking for help, clarification, or responding to other answers. It internally uses the FromStr and Display trait to convert objects around. 0. This is a simplified version of the OOP I want to convert json to: #[derive(Debug, Serialize, Deserialize)] struct Spell { kind: Kind } #[derive(Debug, Serialize, Deserialize)] enum Kind { Particle(Particle) } It will be useful to allow flatten sequences, especially that will very helpful to model of XSD choice types. But obviously I can't actually use this because Gender::Male and Gender::Female both serialize to null. Improve this question. EDITS. §Quickstart. This feels like a simple thing but I can't work it out. §Supported features Plain derived implementations obtained with #[derive(Serialize, Deserialize)] for Rust containers in the Serde data model. ) If I make use of an untagged I experimented with with this and there is a technical issue. Serialization framework for Rust. Here's my enum: enum E { Type1, I can work around this by either nesting VariableDeclaration into a single-variant enum, and using #[serde(untagged)] on the ForStatementInit enum, or by manually "flattening" The answer was to use serde's flatten macro for the file_or_folder that did not exist in the raw data, but was built using a combination of fields in the raw data (per the serde docs It would be ideal for #[serde(flatten)] to play nice with #[serde(tag = "t", content = "t")] too. It can only serialize and deserialize primitives and derivatives thereof (like basic enums or newtypes). If neither of these is what you are seeing, please file an issue. impl Serialize for DBUser<'_> { fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> For parallelism, and since we also support aliases on enum variants, also extend the struct_variant API in a similar way. Without knowing what is in a JSON document, we can deserialize it to serde_json::Value by going through Deserializer::deserialize_any. (I feel like I'm posting this on every serde question. To anyone else arriving here looking for a solution, I have been able to use the flatten workaround described in the serde_qs docs to deserialize nested enum fields using plain serde_urlencoded too. Should you need to customize the serialization behavior for a type in a way that derive does not support, you can implement Serialize yourself. 10` as a `String` to fail. [dependencies] serde = "1. use serde_with::{serde_as, DisplayFromStr}; use std::collections::HashMap; #[serde_as] #[derive(Debug, Clone, Serialize, §Features and Limitations. flatten may be used any number of times within the same struct. Toggle navigation. Host and manage packages Security. // // In the case of a map we need generic type parameters K and V to be // able to set the output type correctly, This method's job is to take your type (&self) and map it into the Serde data model by invoking exactly one of the methods on the given [Serializer]. Manually deserialize struct. The wrapper has a lifetime because I just used a &'a str. TL;DR: It should be fine to use deny_unknown_fields with flatten in this way so long as types used in MutuallyExclusive do not use flatten. Copy link i509VCB commented Aug 31, 2022 #[serde(flatten)] is not allowed on an If not, a #[serde(flatten)] variation that accepts both flattened and nested input would be useful. Deserialization of Gender::Other now works. Container attributes — apply to a struct or enum declaration. Field attributes — apply to one field in a struct or in an enum variant. Sign in Product Actions. When a not yet known variant is detected, I need to simply ignore value and continue processing the others. See How can I use Serde's custom (de)serialization to update a subset of arbitrary input? See also: How can I deserialize an optional field with custom functions using Serde? I am quite new to rust, and am trying to use the csv and serde crates to read a . This allows C-like enums to be formatted as integers rather than strings in JSON, for example. Basically, this requires the deserializer to discover an enum variant by looking at the various fields and capturing variant names as well as field names. In most cases Serde's derive is able to generate an appropriate implementation of Serialize for structs and enums defined in your crate. #[serde(untagged)] {#untagged} Use the untagged enum representation for this enum. I am using a Node struct with common fields for each structs. Default value for a field use serde::Deserialize; #[derive(Deserialize, Debug)] struct Request { // Use the result of a function as the default if "resource" is // not included in the input. Reload to refresh your session. :‌p (or at least you should be able to. Implementing Deserialize for a type tends to be more complicated than implementing I have several non-exhaustive enums which I need to handle nicely. The Same type implements SerializeAs whenever the underlying type implements Serialize and is used to Serde support for querystring-style strings. We should define some tests to understand better how it works. Unable to tell what precis I have an enum defined as: enum Foo { Bar { x: i32, y: i32 }, // many more variants } Given a JSON string {"x": 5, "y": 7} how would I deserialize explicitly to Foo::Bar {x: 5, y: 7}?. I imagine this could all be done with derive macros, and more efficient reuse of the existing EnumAccess implementation rather than needing a separate variant method. If the only field changing is baz, then I would do it with an enum that can be either bar or baz: #[derive(Serialize, Deserialize)] struct Thing { foo: String, #[serde(flatten)] bar_or_baz: BarOrBaz, // 20 more fields version: u16, } #[derive(Serialize, Here the tests for missing and present fail. Flatten would keep its default behavior, but it could be altered using an option (e. It uses several heuristics to guess the right bound, but most importantly it puts a bound of T: Serialize on every type parameter T that is part of a Use the adjacently tagged enum representation for this enum, with the given field names for the tag and content. Allows specifying independent names for serialization vs deserialization: Here is a link to the solution. To activate that functionality we need to use #[serde(untagged)] attribute. Sometimes a map with multiple keys should be treated like a list of enum values. What seems to be currently implemented (though undocumented) at the time of this post is #[serde(other)]. Say I have some external json protocol that has sample messages like I have a small use case for #[serde(flatten)] that did not work as I expected due to the intermediary presence of an Option type. It is supported only within structs that have named I'm trying to implement a way to serialize an enum with various structs into json, but running into some issues with using the flatten command. haven't actually tested it, just inferring. Closed emilio added a commit to §Serde Flatten Value. Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company serde library is smart enough to correctly replace the values with your enums. 1" #[serde(flatten)] foo: MutuallyExclusive, other_field: String, } The Issue. 2. I also looked through serde's documentation, and did find a flatten attribute, but it did not seem to work when I tried applying it to the bars field. This is not really required here but in my actual data / codebase it is very valuable to be able to do this. serde_reflection is meant to extract formats for Rust containers (i. I'm trying to deserialize JSON into a somewhat complicated structure. Should you need to customize the serialization behavior for a type in a way that derive does This seems impossible to fix in serde itself. However, I'm trying to deserialize an internally tagged enum, and that seems to be where stuff goes off the rails. More reading here: serde. Contribute to serde-rs/serde development by creating an account on GitHub. Comments. Find and fix My program parse big enough json document (30MB), on machine with slow CPU it takes 70ms, I want to speedup the process, and I find out that 27% of parsing take place into my Field attributes #[serde(rename = "name")] {#rename} Serialize and deserialize this field with the given name instead of its Rust name. For example, with objects like: There's an issue for this, though it's been open for 3 years with no full resolution so far. The idea is to wrap Foo into a MaybeFoo, where MaybeFoo has a "universal" type to deserialize into as the second choice. All the placeholder type _ will be replaced with ::serde_with::Same. The various deserialize_* methods. emilio mentioned this issue May 4, 2019. The serde-transcode crate provides functionality to "transcode" from an arbitrary Serde Deserializer to an arbitrary Serde Serializer without needing to collect the entire input into an intermediate form in memory. It is a recursively nested "struct" with flatten fields. What version of the csv crate are you using?. I had a look at the If not, a #[serde(flatten)] variation that accepts both flattened and nested input would be useful. 10. My goal is to get JSON {"type": "ThingB", value: 0} to evaluate to Thing::ThingB(ThingB {value: 0}) during deserialization, and vice versa, but only if I'm deserializing to a Thing. Sign in Product GitHub Copilot. g. rename_all You signed in with another tab or window. About; Products OverflowAI; Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI This is probably related to the issues with combining flatten and deny_unknown_fields. I would expect it to either try to deserialize into `ValueType::I32` first, succeed and continue with the next entry, as Instead of manually implementing Serialize you can instead use #[serde(untagged)]. If you can change your Map to a List (simply add -in front of csv and json) — which it seems you want to do, since output_data_specs is a Vec<Sink> — you can use #[serde(with = "serde_yaml::with::singleton_map_recursive")] to use the keys csv and json as enum tags in serde’s default enum representation. Manually implementing Deserialize for a struct. If you only need this for the HashMap in question, you could also follow the suggestion in the Toml issue, which is to keep the definition of Source the same and use the crate, serde_with, to modify how the HashMap is serialized instead:. so @Alistair 's answer is what I ended up using in my code struct JobInformationResponseAll { field_appears_in_all_responses: FooBar, #[serde(flatten)] state: JobInformationResponse // Field name doesn't matter to serde } But I'm not sure whether that works for you, since I certainly haven't seen enough of the spec or any real example messages. Briefly describe the question, bug or feature request. See enum representations for details on this representation. #[derive(Debug, Deserialize)] enum ResultType You signed in with another tab or window. Instant dev environments Issues. serde data formats often represent externally tagged enums as maps with a single key. Not great, but okay for our purposes. This is the correct answer for the question I asked, so I've marked it as correct - though in the code I have I would have to somehow get diesel's . Here is the code: #[derive(Debug, Serialize, Deserial I have an enum that is composed of other enums, similar to the following (serde derives and annotations omitted for brevity):enum Main { A(SubA), B(SubB), } enum SubA { X1, X2, X3 } enum SubB { Y1, Y2, Y3 } Other enum representations are not supported. This relates to this issue in some sense: serde-rs/serde#1183 I'm trying to deserialize XML block with serde_xml_rs but for some reason it doesn't seem to be able to identify and map the result on my enum. #[derive(Serialize, Deserialize)] enum Foo { A { #[serde(flatten)] fields: HashMap<String, String>, } } error: proc-macro derive panicked --> src/main. I understand The flatten attribute inlines keys from a field into the parent struct. For consistency, other human-readable formats are encouraged to develop analogous conventions where possible. Worse, the bugs that result from this issue aren't I have a tuple consisting of an String and a Uuid that I serialize using serde_json: let log_and_id = (String::from("Test string"), test_id); let log_and_id_serialized = serde_json::to_st Hello, Why is this code not running? use serde::{Serialize, Deserialize}; #[derive(Debug, Serialize, Deserialize)] enum Color { Red, Green, Blue } #[derive(Debug, Serialize, Deserialize)] struct Pi Skip to content. Follow asked Nov 8, 2023 at 20:30. Allows specifying independent names for serialization vs deserialization: If the fields api-names are loaded dynamically (say, fetched from the API in a lazy_static), you can't use an enum. Allows specifying independent names for serialization vs deserialization: So I have #[derive(Deserialize, Clone, Debug, Copy)] pub enum ComparisonOperators { #[serde(rename = "=")] EQ, #[serde(rename = "!=")] NEQ, #[serde(rename = Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. 0" serde_json = "1. In fact, the only two ways I can think of to deserialize Tree at all, are to a) leak memory b) implement a I have the following code: extern crate serde; #[macro_use] extern crate serde_derive; #[derive(Debug, Default, Serialize, Deserialize)] pub struct Base { bold Of course, this will not work. Serde will try to match the data against each variant in order and the first one that deserializes successfully is the one returned. It sounds like you want an internally tagged enum: serde. It contains the configuration. In most cases Serde's derive is able to generate an appropriate implementation of Serialize for structs and enums defined in your crate. Sign up Product You can use an untagged enum for this. I want the struct Foo to first take care of the common behaviour, and then pass on to the different Bar for the specifics. use serde::Deserialize; #[derive(Debug,Deserializ Structs and enums in JSON. I would expect that if I had a setup like this: # [derive (Debug, Deserialize)] enum MultipleOptions {FirstThing (HashMap < String, String >), SecondThing (HashMap < String, String >),} # [derive (Debug, Deserialize)] struct AThing {# Options::with_varint_encoding is probably not what you want, since it will only use 1 byte for integers that are less than 256. Derive Serialize and Deserialize that delegates to the underlying repr of a C-like enum. Based on serde-value, serde-value-flatten provides a function to flatten any struct which implement serde::Serialize. It can only be applied to unit enum fields, which limits its usefulness: Default value for a field. csv file. That's only needed if you want to avoid creating an owned value (e. For both failing tests I have by now found a solution. Serialization fails with message: cannot serialize tagged Further support for enums is being tracked in serde-rs/serde#1186 and serde-rs/serde#1189. It doesn't look like the The #[serde(rename = "bar", default)] on the bars field was my first attempt to fix the this, based on quick-xml's documentation, but it obviously does not work. Instead the Serialize and Deserialize impls for OsString map into the Serde data model by treating OsString as a Serde enum. You switched accounts on another tab or window. For the present test the solution is to add a visit_i64 implementation to the OptXVisitor. However this doesn't work, the most obvious example How to properly define the data types such that the JSON de-serialize works fine with Serde/Rust for the following examples? I believe the Hashmap is the culprit somehow. github","path":". (A reduced version of my current attempt is on the playground. #[flatten] a HashMap<String, > Again, we need to fill and read from these structs at some point. de: Make flattened structs and aliases interact correctly. 1" Then, create a structure which implement the serde::Serialize trait and use it with any serde lib internally (or adjacently) tagged or untagged enum variants or #[serde(flatten)]ed fields must not contain: i128 or u128 values; internally tagged newtype variants and #[serde(flatten)]ed fields must not contain: a unit or a unit struct inside an untagged newtype variant; an untagged unit variant ; internally tagged newtype variants, which are #[serde(flatten)]ed together with other fields The problem is that with untagged, Serde tries to parse the data as the first variant of the enum, then if that fails it backtracks and tries the second variant and so on. . I know Serde has a good way to handle adjacent tagged enums. The key is the enum variant name, and the value is the variant value. However I don't understand how to do this manually. 0" present, so I opted for a custom implementation. Some Deserializer implementations for self-describing formats do not care what hint the Visitor gives them, they just want to blindly call the Visitor method corresponding to the data they can tell is in the input. Is there an easy solution to do this with serde and csv? I feel like I missed one or two serde attributes, but I was not able to find the right one in the documentation yet. Assuming the yaml format is set and you're free to change the Rust types, I think the easiest thing to do Field attributes #[serde(rename = "name")] Serialize and deserialize this field with the given name instead of its Rust name. I am currently deseria Skip serializing field. My main problem is that fields that are already part of a flattened struct are still added to the HashMap that should only contain the additional fields. 0" serde_value_flatten = "0. Did not include everything in the question in an attempt to keep it "minimal". I am starting to think I'm gonna have to implement serialization and deserialization of payload myself to handle these JSONs. As the simplest example, here is the builtin Serialize impl for the primitive i32. When deriving Serialize and Deserialize implementations for structs with generic type parameters, most of the time Serde is able to infer the correct trait bounds without help from the programmer. github","contentType":"directory"},{"name":"_skeptic","path":"_skeptic Process an array of values without buffering into a Vec. I haven't found a better way than the current untagged solution, but I also really need to stop thinking about this for If you have fields where the name cannot be known at compile time, you can use serde_json::Value in addition to this solution. html I'm also thinking you should get rid of the AnalysisTypes enum. If you only add the skip_serializing attribute, and then attempt to deserialize the data, it will fail, as it will still attempt to deserialize the skipped field. #[derive(Debug, Deserialize)] struct Side note, despite what the manual says, you can have a deny_unknown_fields struct as the trailing flattened struct in another struct. If you read the serde documentation, you may notice it warns that using deny_unknown_fields in conjunction with flatten is @Shepmaster Because there is some common behaviour related to the member I called common here (in reality, there are more common ones). With #[serde(tag = "foo")]. flatten may be used any number of times within the same struct. The serde_repr crate provides alternative derive macros that derive the same Serialize and Deserialize traits but delegate to the underlying representation of a C-like enum. I ran into this problem myself today. From String Hi all! I'm trying to deserialize a field that may be either a string or a struct; so far, so good – there's even a chunk of the Serde docs about exactly that. My main problem is that fields Hello, i am trying to serialize enumeration with quick-xml crate like: use serde::Serialize; # [derive (Debug, Serialize, PartialEq)] # [serde (rename_all = "lowercase")] I have an enum with some aliases for the variants. e. I'm working on a serializer for a format I came across in the wild which represents all structs with explicit type names, and as a result I Serialize with an added prefix on every field name and deserialize by trimming away the prefix. use serde_with::{serde_as, EnumMap}; It seems like the combination of `#[derive(Serialize, Deserialize)]`, `#[serde(untagged)]` and `#[serde(with)]` does something unexpected. Serde #912. In the example below, we use a serde_json::Value as a dummy-type, as its implementation of Deserialize is universal as can deserialize anything that serde_derive: flatten causes struct serializer to lose access to struct name #2350. If I have an If #[serde(deny_unkown_fields)] is applied to a container that contains a flattened untagged enum it will fail to deserialize inputs even if the input does not contain any unknown fields. By default, enums are externally tagged and differentiating between "result" and "error" should just work. Commented Nov Better diagnostics for #[serde(flatten)] on an enum variant #2272. I think it will require some larger changes on the Hi, i am trying to implement custom serde serializer. Custom serialization. I'm open to better ways to fix it, but I can't think of any other that isn't a breaking change Fixes serde-rs#1504. Thanks for the help! #[derive(Serialize, Deserialize, Debug)] #[serde(untagged)] enum Data { Trade(Trade), Order(Order), None {}, } #[derive(Serialize, Deserialize, Debug)] struct Msg { channel: String, event: String, data: Data, } system Closed The most straightforward way to represent this JSON using Serde is with an adjacently tagged enum. It will replace a number with Value::Number, a string with Value::String, intrinsic function with appropriate representation. We can tag the types. What is the best way to do that? It depends. This snippet from #181 (comment) pretty much captures what I'm after: enum Field { Id, Event, Method, Other(S Normally you handle missing levels by tagging with #[serde(flatten)] {"a":1} doesn't contain the subfields from b1 or c1. Thanks for the help! #[derive(Serialize, Deserialize, Debug)] #[serde(untagged Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company . It involves adding a serde field attribute with a custom deserializer for only that field. Here, the serde data model refers to the data types defined within serde, which correspond closely to Rust’s type system. `serde:from_str()` tries to deserialize every entry in the array with my custom `deserialize` function. Copy link mammothbane commented Dec 21, 2022 • edited Loading. The enum is placed as field inside a struct. This would make the interface awful. Thus Tree can't be zero-copy deserialized. You signed out in another tab or window. Effectively it acts as though OsString were defined as the following type, even though this does not match its definition on any individual platform. Serializing a primitive. Non-self-describing formats like Postcard need to be told what is in the input in order In most cases Serde's derive is able to generate an appropriate implementation of Deserialize for structs and enums defined in your crate. There is currently no way to detect this as serde does not communicate to the serialization interface that flattening is requested. Struct flattening. Open i509VCB opened this issue Aug 31, 2022 · 0 comments Open Better diagnostics for #[serde(flatten)] on an enum variant #2272. you just create a read-only struct around read-only string embedded in binary). 0" serde_derive = "1. I'm not sure how to fix this but with bincode being used to transfer data for ipc it's not uncommon now to have objects that are internally using flatten. NOTE: Using skip_serializing does not skip deserializing the field. I suspect we will need a format-specific optional API on Deserializer for buffering data in a way that is consistent for that format. The code is generated at runtime with Custom serialization. If you have a struct with an enum field and you want to serialize the enum to a string using Serde and deriving Serialize, you can use the rename_all or rename attribute macros. Example for JSON (but it's not as expressive as for XML): Playground use serde::{Deserialize, Serialize}; #[derive(Debug, Parti Contribute to serde-rs/serde development by creating an account on GitHub. To avoid this we first parse the document as a map with a union of the metadata/package entries and then convert Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company I've hit a couple occasions where I wanted to serialize/deserialize an enum and basically flatten a particular newtype variant. This representation can handle enums containing any type of variant. I would like to prefix the flatten Serde (pronounced "seer-dee") is a fast, flexible, powerful, and easy to use serialization and deserialization library for PHP that supports a number of standard formats. rs/enum-representations. By default, the variants of Calculation will be converted to the JSON strings Perimeter and Area. This includes the built-in Rust standard library types Vec<T> as you can see in the above example, as well as structs or enums annotated with #[derive(Serialize)]. The methods are a big enum with #[serde(tag = "method", content = "params")] However I can't flatten them into the serialization because they are not exposed. There are some other JSON-specific assumptions baked into Content too. The JSON itself is simple - it's a single, flat object (all field values are either numbers, strings, or booleans). structs and enums) with “reasonable” implementations of the Serde traits Serialize and Deserialize. derive. Allows specifying independent names for serialization vs deserialization: I try to flatten this struct, but #[serde(flatten)] doesn't work as expected Struct example: #[derive(Serialize, Deserialize, Debug)] struct App { version: String, build_date: String, libraries: Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company Struct flattening. Serialize and deserialize C-like enum as underlying repr - dtolnay/serde-repr. Serializing now works, Deserializing gives the following error: Serde can actually do this. you don't want to create a String just to deserialize it into an enum variant and then throw it away). §Examples I'm trying to create objects from text, so I decided to use serde, but I'm struggling to write json for enum variants. The above code actually works when only one of those fields is present, however I have a problem. In the example, it means that the u32 values will serialize with the Serialize implementation of u32. Please use the skip attribute to skip both serializing and deserializing (see Field Attributes: skip). Don't parse directly into your command structures! This also give you the ability to insert validations between the two steps. it's adjacent to other keys inside of a different struct and the key that contains the Value determines its type. Variant attributes #[serde(rename = "name")] Serialize and deserialize this variant with the given name instead of its Rust name. Should you need to customize the deserialization behavior for a type in a way that derive does not support, you can implement Deserialize yourself. However some of these structs have fields with the same name, which make the output unpractical to read. In your case that will work perfectly fine. use serde::{Serialize, Deserialize}; use enum_dispatch::enum_dispatch; #[derive(Debug, Clone, Serialize, Deserialize)] struct Generator { source_id: String, id: String, } Serialize enum as number. That requires to always have the field "jsonrpc": "2. For users who do not require nested URL parameters, it is highly recommended that the serde_urlencoded crate is used The actual structure uses #[serde(flatten)] to capture extra columns since it's used in a localization format for a game engine. You can set the visibility of the generated module by prefixing the module name with a module visibility. Navigation Menu Toggle navigation . The flatten attribute inlines keys from a field into the parent struct. If I add the flatten tag to the field, the deserialization fails with the error no variant of #[derive(Deserialize, Debug)] struct A { #[serde(flatten)] a: HashMap<String, String>, #[serde(flatten)] b: HashMap<String, String>, } serde makes a difference here You can use #[serde(default)] with any type that implements Default including any enum, with any serde representation. Navigation Menu Toggle navigation. This library aims for compatability with the syntax of qs and also of the Rack::Utils::parse_nested_query implementation. I think, what happens is serde JSON parser is confused when it is asked to deserialize into this Content (used internally by serde for tag / flatten processing). Serde's derive macro through #[derive(Serialize, Deserialize)] provides reasonable default serialization behavior for structs and enums and it can be customized to some extent using attributes. Here's what I mean: #[derive(Serialize, Without the #[serde(flatten)] line, this would be used to parse JSON like this: { "users": [""], "pagination": { "limit": 100, "offset": 0, "total": 200 } } But by flattening the pagination member, I am currently trying to find a way to have serde capture additional fields inside a struct when having an enum field in the struct also flattened. For the missing test the solution is to add #[serde(default)] to the x field of the A::B enum variant, telling serde to use the default value when the field is missing in the input. But in my case, the type is inside an adjacent map called meta . However, there are exceptions, for which it is not obvious how to serialize them into flat parameters list: Handwritten generic type bounds. enum OsString { Unix(Vec < u8 >), Windows(Vec <u16>), // and other platforms} The flexibility around mapping You signed in with another tab or window. Of course, this will work if you try to deserialize a static string into a type (i. We could do nothing and hope that our parsing library (serde in this case) can figure out which type it should be based on the available fields. toml: [dependencies] serde = "1. In hindsight, the documentation is pretty clear, but there are no examples, so I overlooked it. You can start using it by first adding it to your Cargo. Adding #[serde(untagged)] does the trick: #[derive(Debug, Deserialize)] struct MultiLangString { de: Option<String>, en: Option<String>, } #[derive(Debug, Deserialize)] I just experimented with different enum representations. As another example of an untagged enum, this enum can be deserialized from either an integer or an array of two strings: I saw visitor and stuff in the example in documentation. Implement Deserialize for a custom map type use std::fmt; use std::marker::PhantomData; use serde::de::{Deserialize, Deserializer, Visitor, MapAccess}; // A Visitor is a type that holds methods that a Deserializer can drive // depending on what is contained in the input data. Otherwise, forwarding to other types' Deserialize is entirely possible and easy. I can see this being useful in cases where you have control over the data format and want to filter out malformed results, but since I am receiving data from a third-party source it is harder to determine who is at fault for errors during parsing. enums; flatten; serde; Share. g #[serde(flatten = accept)]or another attribute like #[serde(allow_flattened)]. Foo::Bar in my example, rather than resort to something like #[serde(untagged)] which is a poor fit when you I need to be able to serialize and deserialize both older and newer records. Skip to content. As another example of an untagged enum, this enum can be deserialized from either an integer or an array of two strings: Robust Rust library for flattening JSON objects. Ideally I would be able to call into the deserializer for a particular variant, i. Netwave suggested adding the #[serde(tag = "type")] attribute. §Examples §JSON Map with multiple keys. enum OsString { Unix(Vec < u8 >), Windows(Vec <u16>), // and other platforms} The flexibility around mapping Hi, I'm trying to implement a custom serialization for JsonRpc. rs:6:21 | 6 §Serde Flatten Value. Automate any workflow Packages. #[serde(default Working Solution. 5. It fails appropriately when unknown fields are encountered, because the Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company The Deserialize implementation of a type with a field annotated #[serde(flatten)] currently buffers up all of the unknown map entries in memory, and then deserializes the flattened value from them at the end. Container attributes #[serde(rename = "name")] {#rename} Serialize and deserialize this struct or enum with the given name instead of its Rust name. perfect, #1189 is my use case Reply mitsuhiko redis-rs • Additional comment actions. This took me a few attempts to get right, so here's a note to self. I ran into not being able to deserialize the JSON object back that I got when serializing my structure. struct Duration { secs: u64, nanos: u32, } . Almost any type that implements Serde’s Serialize trait can be serialized this way. ) FluxDensityType is an enum with two variants visible in the yaml ("list" and "power_law"). Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company Serde will try to match the data against each variant in order and the first one that deserializes successfully is the one returned. Basic struct of this crate. "tagging" types means using some field to determine which type a json value will correspond to and should be parsed into. I highly recommend using a 2-step approach: use Serde to read the input plain and then use the conversion protocols Rust gives you to construct your CreateUser out of it. When I contributed the flatten support I did not find a way to make it work with protocols that do not have maps without length information. If there were only one dimension along which this structure could exist, it'd be easy. This requires repetitive implementations of all the Deserializer trait methods. However, it can have different structures depending on what it represents. 1 (/pla Usecase I want to serialize a struct containing other structs to CSV, which is why I use flatten. html. Seth Lutske Seth Lutske. Instead of thousand of words This code is failed to compile due to panic in serde derive: #[derive(Deserialize)] enum Failed { Tuple(f64, String), Flatten { #[serde(flatten)] nested: Nested, }, } Output: Compiling playground v0. It's hard to imagine a derived Deserialize implementation to get this right. Provide details and share your research! But avoid . It could filter for the "cpu@" prefix which you show in your example. The example TOML code in the question is an example of the untagged enum representation. This is useful for serializing fields as camelCase or serializing fields with names that are reserved Rust keywords. But, in a small number of records (that I've just been ignoring until now), there is non-UTF8 data in one of the fields, and of course they fail to parse into a String. This is a (somewhat) minimal example: use std::collections::HashMap; use github crates-io docs-rs. Is this something you would accept in Serde? If it is, I could try submitting a PR given the right pointers. Looking at the docs, I can see easily how to use the ByteRecord Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company Transcode one format into another. The problem Suppose I have an enum that wraps exactly one element, as per the following code: #[macro_use] extern crate serde_derive; extern crate serde; extern crate serde_json; #[derive(Serialize, Debug)] enum E { E(Vec<usize>) } fn ma use serde::{Serialize, Deserialize}; #[derive(Serialize, Debug, Copy, Clone)] pub enum Symbol { #[serde(alias = "BOW")] Bow, #[serde(alias = "SWORD")] Sword, Poison(u8), // Many more variant } So far, it's work pretty well with serializing and deserializing when using files generated by Rust. 1. Normally you handle missing fields by tagging (an Option) with #[serde(default)] It seems that the combination of the two doesn't work on deserialization. Instantiate it and use the method flatten to flatten a JSON object. #[serde(default = "default_resource")] resource: String, // Use the type's implementation of std::default::Default if // "timeout" is not included in the input. Deserializing a field that uses #[serde(flatten)] on a HashMap<String, String> fails if the value in a record looks like a number. Querystrings are not formally defined and loosely take the form of nested urlencoded queries. This provides a fully general way to convert any self-describing Serde data format into any other Serde data format in a memory None of these types can be safely embedded within untagged enums, and probablly can't use #[serde(flatten)] or other features that also depend in intermediate deserializers. Write better code with AI Security. It thinks it needs to do an "arbitrary number" and yield a map, but in reality, it is not (parts of serde outside of Serde JSON don't know how to process that "arbitrary precision Where variant returns an identifier for each variant on the enum. use serde_with::{serde_as, EnumMap}; Context. My program is a process scheduler that watches processes based on some given criteria (name, running/not_running, resource usage ) and executes some actions when criteria matches. Supported serde attributes: rename; rename-all; tag; content; untagged; skip; skip_serializing; skip_deserializing; skip_serializing_if = "Option::is_none" flatten; default; When ts-rs encounters an unsupported serde attribute, a warning is This seems like by far the most convenient solution, but I do worry that it would cover up meaningful errors. Automate any workflow Codespaces. The problem is that in serde deserialization is controlled by the Deserialize implementation. However, #[serde(default)] is a field attribute, so you Is there any way to instruct serde to flatten these structures into one, or will I just have to implement custom serialization/deserialization? As far as I can tell there's no serde attribute that will do what you want. impl Serialize enum as number Serialize fields as camelCase Skip serializing field Derive for remote crate Manually deserialize struct Discarding data Transcode into another format Either string or struct Another option would be to create a custom deserialization function for the cpu field. Sadly that's a really complex one. For chat, consider trying the #general or #beginners channels of the unofficial Hi, I have designed a conveient generic enum that I want to deserialize from a config file. The Deserialize impl below corresponds to the following struct:. The problem is that the enum is "key-tagged", i. Other enum representations are not supported. 0" serde_repr = "0. mammothbane opened this issue Dec 21, 2022 · 3 comments Comments. – drewtato. Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company or you could use an enum cause it look like your Cars is an enum where you only show to us one type: #[derive(Serialize, Deserialize, Debug, Clone)] pub enum Foo { Car(Car), } You could also reverse the problem with: #[derive(Serialize, Deserialize, Debug, Clone)] pub struct Wheel { #[serde(flatten, default)] pub car: Foo, // or pub foo: Foo, if it make more sense I'm using the CSV crate to parse a bunch of log formats conveniently into structs with serde_derive. Instead, you can deserialize to an untagged enum: {"payload":{"allShortcutsEnabled":false,"fileTree":{"":{"items":[{"name":". Serde is structural; it doesn't really care about how the data is actually Custom serialization. There are a few ways to represent something like this in JSON. Variant attributes — apply to a variant of an enum. #1519. I had a look at the You signed in with another tab or window. 1" Then, create a structure which implement the serde::Serialize trait and use it with any serde lib JSON uses this approach when deserializing serde_json::Value which is an enum that can represent any JSON document. For unusual needs, Serde allows full customization of the serialization behavior by manually implementing Serialize and Deserialize traits for your use serde_derive; use serde_json::Number; #[derive(Serialize, Deserialize)] struct DictionaryValue { data: Number, } I am looking to access the JSON data in this manner: #[derive(Serialize, Deserialize)] struct Dictionary { key: String, value: DictionaryValue, } How can I (de)serialize my JSON data into/from Dictionary using Serde? Instead the Serialize and Deserialize impls for OsString map into the Serde data model by treating OsString as a Serde enum. In order to implement flatten on arbitrary structures you need to call its Deserialize implementation at which point it will expect to drive the process until it is complete. The details depend on what you want to do exactly. i509VCB opened this issue Aug 31, 2022 · 0 comments Labels. That’s fine, but we’d prefer it if the strings were all lowercase. This approach has a couple o github crates-io docs-rs. Customized derived Based on your examples and definition of the problem, what you could do is to define the main object's type as an enum, and each variant as a separate struct: pub enum Value { Null, Bool(bool), Number(Number), String(String), Array(Vec<Value>), Object(Map<String, Value>), } Assume that there is no further reference needed to the n_width field in this program, so no need to open the code by the Rust development team, only the JSON team would make the changes to the JSON file and the struct file. The serde documentation provides a clear explanation of the data model, including an example using OsString , which is highly recommended if you’re not already familiar with Not necessarily more concise than a custom serializer, but certainly a good bit more trivial is a solution with [serde(from and into)]. It is supported only within structs that have named fields, and the field to which it is applied must be a struct or map type. Serde knows different ways to represent enums, documented here. Changing #[serde(tag = "type")] to #[serde(untagged)] on the Thing enum causes the opposite problem: Thing instances serialize properly, but don't get parsed correctly anymore. In this enum __Field structs for both variants generated like the variant contains flattened field, but that is true only for the second field: #[derive(Deserialize)] enum Enum<T> { Simple { a: i32, }, Flatten { #[serde(flatten)] flatten Example use case: #[derive(Serialize, Deserialize)] enum TextOrRegex { /// Text is assumed to be default option #[serde(untagged)] Text(String), /// Regex must be uses enum and serde(tag="") type field can be out of order in json/yaml (doesn't have to be first) type field is included when serializing back to json/yaml; The trick was to use enum_dispatch. As another example of an untagged enum, this enum can be deserialized from either an integer or an array of two strings: Not possible. 6k 9 9 gold badges 46 46 silver badges 108 108 bronze badges. §Examples I am currently trying to find a way to have serde capture additional fields inside a struct when having an enum field in the struct also flattened. Deserializing a struct is somewhat more complicated than deserializing a map in order to avoid allocating a String to hold the field names. For unusual needs, Serde allows full customization of the serialization behavior by manually implementing Serialize and Deserialize traits for your In some sense it would be necessary to detect that flattening is requested, and to then dump out the structural form of the value rather than the reference. Example: use ts_rs::TS; use serde::Serialize; #[derive(Serialize, TS)] #[serde(tag = "type")] pub enum Thing { #[serde(rename_all = "camelCase")] A { display_name The approach taken in this PR is due to some outstanding quirks in `serde_yaml`: - dtolnay/serde-yaml#165 (comment) - dtolnay/serde-yaml#388 Our usage of `#[serde(flatten)]` in `LockfileData` caused attempting to parse `2` or `0. It makes sense that is_human_readable was intended to be best-effort, but unfortunately it's being relied upon within the ecosystem. While trying to find a more rustic way of handling casting to rust types while reading a binary file by using its XML description it was suggested to use an enum with unit types instead of deserializing a string or &str, to get more guarantees from the compiler and avoid lifetimes; however, getting the XML to deserialize directly into the enum unit variants is causing some At the moment, I can't find a way to enforce that only a single variant of an enum is set for a field when using #[serde(flatten)]. A Serde Serializer is responsible for selecting the convention by which Rust structs and enums are represented in that format. For example the representation of Serde enums happens to be what serde_json uses but not necessarily shared by other formats. Here's what happens with the example above: Serde is asked to parse a value of type Foo, which is untagged, so Serde tries to parse a value matching the first variant. However, a slightly different variant with only flatten and no enums: use std::collections::BTreeMap; use serde::Deserialize; #[derive(Debug, Deserial Oh wow, thanks for that reference. , and a Serialize and deserialize C-like enum as underlying repr - dtolnay/serde-repr. I solved it by both removing the #[serde(flatten)] and also adding #[serde(untagged)]. Sadly, when I chose the serialization way in Python, I serialized the poison To demonstrate, the following code works: use serde::{Serialize, Skip to main content. You just need to Serialize and Deserialize for an enum. biujnluz gmcjbc czna edq yckrdy acifqd cekah ypr ajt iatp