de/serializing yaml 或 json 使用 serde 时如何解构枚举？
How to destructure enum when de/serializing yaml or json with serde?
我有一段 serde 代码可以执行我想要的操作，但我不喜欢它的执行方式。我正在寻求有关如何改进它的帮助。
use std::any::Any;
trait Model: std::fmt::Debug + Any {
fn as_any(&self) -> &dyn Any;
}
impl Model for Generator {
fn as_any(&self) -> &dyn Any {
self
}
}
impl Model for Connector {
fn as_any(&self) -> &dyn Any {
self
}
}
#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
pub struct Generator {
id: String,
#[serde(rename = "sourceID")]
source_id: String,
}
#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
pub struct Connector {
id: String,
#[serde(rename = "sourceID")]
source_id: String,
}
#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
#[serde(tag = "type")]
enum AllModels {
Generator(Generator),
Connector(Connector),
}
fn main() {
let data = r#"
- sourceID: "generator-01"
id: "connector-01"
type: "Generator"
- sourceID: "geneiator-01"
type: "Connector"
id: "connector-01"
"#;
let p: Vec<Box<dyn Model>> = serde_yaml::from_str::<Vec<AllModels>>(&data)
.unwrap()
.into_iter()
.collect();
println!("{:?}", p);
let l = serde_yaml::to_string(&p.into_iter().collect::<Vec<AllModels>>());
println!("{:?}", l);
}
impl std::iter::FromIterator<AllModels> for Vec<Box<dyn Model>> {
fn from_iter<I: IntoIterator<Item = AllModels>>(iter: I) -> Self {
let mut v: Vec<Box<dyn Model>> = Vec::new();
for i in iter {
match i {
AllModels::Generator(d) => {
v.push(Box::new(d));
}
AllModels::Connector(d) => {
v.push(Box::new(d));
}
}
}
v
}
}
impl std::iter::FromIterator<std::boxed::Box<dyn Model>> for std::vec::Vec<AllModels> {
fn from_iter<I: IntoIterator<Item = Box<dyn Model>>>(iter: I) -> Self {
let mut v: Vec<AllModels> = Vec::new();
for i in iter {
if let Some(model) = i.as_any().downcast_ref::<Generator>() {
v.push(AllModels::Generator(model.clone()));
} else if let Some(model) = i.as_any().downcast_ref::<Connector>() {
v.push(AllModels::Connector(model.clone()));
}
}
v
}
}
我想要实现的是 de/serialize yaml 到多个结构之一，根据它解析的 yaml 中 type 字段的值动态选择它应该反序列化到哪个结构。例如
- id: Foo
source: Bar
type: Connector
应该解析成struct Connector
我想我可以使用枚举表示来处理这个问题，但是，它会产生不希望的副作用 - 默认情况下遵循 yaml:
- id: Foo
source: Bar
type: Connector
- id: Foo
source: Bar
type: Generator
将被解析为：
[Connector(Connector{...}), Generator(Generator{...})]
所以我的结构被包裹在枚举变体中。为了“打开它”，我想我可以实现 FromIterator<AllModels> for Vec<Box<dyn Model>> ，多亏了它并键入 conversion/coercion（不确定哪个是正确的词），输出更改为：
[Connector{...}, Generator{...}]
到目前为止还不错。
我在使用此解决方案时遇到的两个问题是：
- 代码重复 - 对于每个新结构（连接器，生成器，......）我必须更新
enum AllModels 和 match arm inside FromIterator 实现 - 后者是困扰我最我可能可以用宏来完成，但我还没有学会如何编写它们，在我这样做之前，我想探索其他可能的解决方案
- 额外迭代 - 为了从
Vec<enum variant> 转换为 Vec<struct>，我需要执行以下操作：let p: Vec<Box<dyn Model>> = serde_yaml::from_str::<Vec<AllModels>>(&data).unwrap().into_iter().collect();。我更愿意在没有额外迭代的情况下进行转换
我已经考虑了一些选项，但我不知道如何实施它们...
一个。 serde 容器属性 from/into docs
#[serde(from = "FromType")] - 我认为它的工作方式是将我的枚举变量直接强制转换为所需的结构，没有额外的迭代，也没有代码重复。但是，我未能实现它 - Playground.
当我尝试添加 from 属性时
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "type")]
enum AllModels {
Gene(Generator),
Connector(Connector),
}
编译器会骂我
❯ cargo r
Compiling serdeissue v0.1.0 (/sandbox/serdeissue)
error[E0277]: the trait bound `Box<dyn Model>: From<AllModels>` is not satisfied
--> src/main.rs:21:24
|
21 | #[derive(Debug, Clone, Serialize, Deserialize)]
| ^^^^^^^^^ the trait `From<AllModels>` is not implemented for `Box<dyn Model>`
|
= help: the following implementations were found:
<Box<(dyn StdError + 'a)> as From<E>>
<Box<(dyn StdError + 'static)> as From<&str>>
<Box<(dyn StdError + 'static)> as From<Cow<'a, str>>>
<Box<(dyn StdError + 'static)> as From<std::string::String>>
and 22 others
= note: required because of the requirements on the impl of `Into<Box<dyn Model>>` for `AllModels`
= note: required by `into`
= note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0277]: the trait bound `dyn Model: Serialize` is not satisfied
--> src/main.rs:21:24
|
21 | #[derive(Debug, Clone, Serialize, Deserialize)]
| ^^^^^^^^^ the trait `Serialize` is not implemented for `dyn Model`
|
::: /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/ser/mod.rs:247:18
|
247 | fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
| - required by this bound in `serialize`
|
= note: required because of the requirements on the impl of `Serialize` for `Box<dyn Model>`
= note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0277]: the trait bound `dyn Model: Deserialize<'_>` is not satisfied
--> src/main.rs:21:35
|
21 | #[derive(Debug, Clone, Serialize, Deserialize)]
| ^^^^^^^^^^^ the trait `Deserialize<'_>` is not implemented for `dyn Model`
|
::: /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/de/mod.rs:539:12
|
539 | D: Deserializer<'de>;
| ----------------- required by this bound in `_::_serde::Deserialize::deserialize`
|
= note: required because of the requirements on the impl of `Deserialize<'_>` for `Box<dyn Model>`
= note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0277]: the trait bound `AllModels: From<Box<dyn Model>>` is not satisfied
--> src/main.rs:21:35
|
21 | #[derive(Debug, Clone, Serialize, Deserialize)]
| ^^^^^^^^^^^ the trait `From<Box<dyn Model>>` is not implemented for `AllModels`
|
::: /home/marcin/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/convert/mod.rs:372:1
|
372 | pub trait From<T>: Sized {
| ------------------------ required by this bound in `From`
|
= note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
我的攻击角度如下：使用error msg to copy-pasteroni-dummy-implementoni missing trait bounds:
impl From<AllModels> for Box<dyn Model> {
fn from(am: AllModels) -> Self {
Box::new(Generator{id:String::from("arst"),source_id:String::from("arst")})
}
}
impl Serialize for dyn Model {
fn serialize(&self) -> Self {
Box::new(Generator{id:String::from("arst"),source_id:String::from("arst")})
}
}
impl Deserialize<'_> for dyn Model {}
impl From<Box<dyn Model>> for AllModels {
fn from(dm: Box<dyn Model>) -> Self {
AllModels::Gene(Generator{id:String::from("arst"),source_id:String::from("arst")})
}
}
但随后发生了这种情况：
❯ cargo r
Compiling serdeissue v0.1.0 (/sandbox/serdeissue)
error[E0277]: the size for values of type `(dyn Model + 'static)` cannot be known at compilation time
--> src/main.rs:75:6
|
75 | impl Deserialize<'_> for dyn Model {}
| ^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
|
::: /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/de/mod.rs:530:29
|
530 | pub trait Deserialize<'de>: Sized {
| ----- required by this bound in `Deserialize`
|
= help: the trait `Sized` is not implemented for `(dyn Model + 'static)`
对我来说游戏结束了
乙。 erased-serde
这似乎是完成这项工作的正确工具，但同样，我 运行 在实施它时遇到了问题（难怪 - 我不知道自己在做什么:)
use erased_serde::{Deserializer, Serializer, serialize_trait_object};
use serde::{Serialize, Deserialize};
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Generator {
id: String,
source: String,
}
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Connector {
id: String,
source: String,
}
trait Model: std::fmt::Debug + erased_serde::Serialize {}
erased_serde::serialize_trait_object!(Model);
impl Model for Generator {}
impl Model for Connector {}
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "type", into = "Box<dyn Model>", from = "Box<dyn Model>")]
enum AllModels {
Generator(Generator),
Connector(Connector),
}
fn main() {
let data = r#"
- source: "generator-01"
id: "g-01"
type: "Generator"
- source: "connector-01"
type: "Connector"
id: "c-01"
"#;
let p: Vec<Box<dyn Model>> = serde_yaml::from_str(&data).unwrap();
println!("{:?}", p);
}
impl From<AllModels> for Box<dyn Model> {
fn from(am: AllModels) -> Self {
Box::new(Generator{id:String::from("arst"),source_id:String::from("arst")})
}
}
// impl Serialize for dyn Model {
// fn serialize(&self) -> Self {
// Box::new(Generator{id:String::from("arst"),source_id:String::from("arst")})
// }
// }
impl Deserialize<'_> for dyn Model {}
impl From<Box<dyn Model>> for AllModels {
fn from(dm: Box<dyn Model>) -> Self {
AllModels::Generator(Generator{id:String::from("arst"),source_id:String::from("arst")})
}
}
// impl std::convert::From<AllModels> for Box<dyn Model> {
// fn from(m: AllModels) -> Self {
// Box::new(Generator {source_id: String::from("i"), id: String::from("r")})
// }
// }
我在编译时遇到这个错误：
❯ cargo r
Compiling serdeissue v0.1.0 (/sandbox/serdeissue)
warning: unused imports: `Deserializer`, `Serializer`, `serialize_trait_object`
--> src/main.rs:1:20
|
1 | use erased_serde::{Deserializer, Serializer, serialize_trait_object};
| ^^^^^^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^
|
= note: `#[warn(unused_imports)]` on by default
error[E0277]: the size for values of type `(dyn Model + 'static)` cannot be known at compilation time
--> src/main.rs:76:6
|
76 | impl Deserialize<'_> for dyn Model {}
| ^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
|
::: /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/de/mod.rs:530:29
|
530 | pub trait Deserialize<'de>: Sized {
| ----- required by this bound in `Deserialize`
|
= help: the trait `Sized` is not implemented for `(dyn Model + 'static)`
我认为 erased_serde 可以提供帮助，也许可以，但我不知道如何实施它。
遗憾的是我不能使用 typetag crate，因为它不支持我需要的 wasm 编译目标。我不考虑对每个枚举变体使用 #[serde(serialize_with = "path")]，因为它使我的问题 #1 比现在更糟。
我也知道这个问题 however the code provided by @dtolnay 无法编译，我不知道如何修复它
❯ cargo r
Compiling serdeissue v0.1.0 (/sandbox/serdeissue)
error[E0603]: module `export` is private
--> src/main.rs:168:10
|
168 | #[derive(Serialize)]
| ^^^^^^^^^ private module
|
note: the module `export` is defined here
--> /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/lib.rs:275:5
|
275 | use self::__private as export;
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0603]: module `export` is private
--> src/main.rs:173:10
|
173 | #[derive(Serialize)]
| ^^^^^^^^^ private module
|
note: the module `export` is defined here
--> /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/lib.rs:275:5
|
275 | use self::__private as export;
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0603]: module `export` is private
--> src/main.rs:179:10
|
179 | #[derive(Serialize)]
| ^^^^^^^^^ private module
|
note: the module `export` is defined here
--> /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/lib.rs:275:5
|
275 | use self::__private as export;
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0603]: module `export` is private
--> src/main.rs:184:10
|
184 | #[derive(Serialize)]
| ^^^^^^^^^ private module
|
note: the module `export` is defined here
--> /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/lib.rs:275:5
|
275 | use self::__private as export;
| ^^^^^^^^^^^^^^^^^^^^^^^^^
warning: trait objects without an explicit `dyn` are deprecated
--> src/main.rs:176:22
|
176 | widgets: Vec<Box<WidgetTrait>>,
| ^^^^^^^^^^^ help: use `dyn`: `dyn WidgetTrait`
|
= note: `#[warn(bare_trait_objects)]` on by default
看来我正在寻找的功能正在等待在这里实现：https://github.com/serde-rs/serde/issues/1402
还有这个问题https://github.com/serde-rs/serde/issues/1350 which suggests manual Deserializer implementation Playground。游乐场代码表明这可以帮助解决我的问题 #2“额外迭代”，但是代码实现中仍然有一些重复，因此我仍在寻找更好的答案。
编辑：我也在考虑 Enum or trait object，无法确定评估我是否需要其中之一的正确方法。
我找到了一个令我满意的解决方案：
- 圆滑
- 无代码重复
- 没有动态调度，没有额外的迭代
- 使用
enum 和 serde(tag="...")
type 字段在 json/yaml 中可能是乱序的（不必是第一个）
时包含 type 字段
诀窍是使用 enum_dispatch。
use serde::{Serialize, Deserialize};
use enum_dispatch::enum_dispatch;
#[derive(Debug, Clone, Serialize, Deserialize)]
struct Generator {
source_id: String,
id: String,
}
#[derive(Debug, Clone, Serialize, Deserialize)]
struct Gate {
source_id: String,
id: String,
}
#[enum_dispatch]
trait Model {fn time_advance(self, a:i32,b:i32) -> i32;}
impl Model for Generator { fn time_advance(self,a:i32,b:i32) -> i32 {a+b} }
impl Model for Gate { fn time_advance(self,a:i32,b:i32) -> i32 {a+b} }
#[enum_dispatch(Model)]
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "type")]
enum ModelTypes {
Generator(Generator),
Gate(Gate),
}
fn main() {
let s = r#"
- source_id: "generator-01"
id: "connector-01"
type: "Generator"
- source_id: "geneiator-01"
type: "Gate"
id: "connector-01"
"#;
let data: Vec<ModelTypes> = serde_yaml::from_str(s).unwrap();
println!("{:?}", serde_yaml::to_string(&data));
for d in data {
println!("{:?}", d.time_advance(4, 2));
}
}
[package]
name = "enum_unpack"
version = "0.1.0"
authors = ["---"]
edition = "2018"
[dependencies]
serde = { version = "1.0.124", features = ["derive"] }
serde_yaml = "0.8.1"
enum_dispatch = "0.3.5"
输出：
> cargo run
Compiling enum_unpack v0.1.0 (.../enum_unpack)
Finished dev [unoptimized + debuginfo] target(s) in 0.66s
Running `target/debug/enum_unpack`
Ok("---\n- type: Generator\n source_id: generator-01\n id: connector-01\n- type: Gate\n source_id: geneiator-01\n id: connector-01\n")
6
6
我有一段 serde 代码可以执行我想要的操作，但我不喜欢它的执行方式。我正在寻求有关如何改进它的帮助。
use std::any::Any;
trait Model: std::fmt::Debug + Any {
fn as_any(&self) -> &dyn Any;
}
impl Model for Generator {
fn as_any(&self) -> &dyn Any {
self
}
}
impl Model for Connector {
fn as_any(&self) -> &dyn Any {
self
}
}
#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
pub struct Generator {
id: String,
#[serde(rename = "sourceID")]
source_id: String,
}
#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
pub struct Connector {
id: String,
#[serde(rename = "sourceID")]
source_id: String,
}
#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
#[serde(tag = "type")]
enum AllModels {
Generator(Generator),
Connector(Connector),
}
fn main() {
let data = r#"
- sourceID: "generator-01"
id: "connector-01"
type: "Generator"
- sourceID: "geneiator-01"
type: "Connector"
id: "connector-01"
"#;
let p: Vec<Box<dyn Model>> = serde_yaml::from_str::<Vec<AllModels>>(&data)
.unwrap()
.into_iter()
.collect();
println!("{:?}", p);
let l = serde_yaml::to_string(&p.into_iter().collect::<Vec<AllModels>>());
println!("{:?}", l);
}
impl std::iter::FromIterator<AllModels> for Vec<Box<dyn Model>> {
fn from_iter<I: IntoIterator<Item = AllModels>>(iter: I) -> Self {
let mut v: Vec<Box<dyn Model>> = Vec::new();
for i in iter {
match i {
AllModels::Generator(d) => {
v.push(Box::new(d));
}
AllModels::Connector(d) => {
v.push(Box::new(d));
}
}
}
v
}
}
impl std::iter::FromIterator<std::boxed::Box<dyn Model>> for std::vec::Vec<AllModels> {
fn from_iter<I: IntoIterator<Item = Box<dyn Model>>>(iter: I) -> Self {
let mut v: Vec<AllModels> = Vec::new();
for i in iter {
if let Some(model) = i.as_any().downcast_ref::<Generator>() {
v.push(AllModels::Generator(model.clone()));
} else if let Some(model) = i.as_any().downcast_ref::<Connector>() {
v.push(AllModels::Connector(model.clone()));
}
}
v
}
}
我想要实现的是 de/serialize yaml 到多个结构之一，根据它解析的 yaml 中 type 字段的值动态选择它应该反序列化到哪个结构。例如
- id: Foo
source: Bar
type: Connector
应该解析成struct Connector
我想我可以使用枚举表示来处理这个问题，但是，它会产生不希望的副作用 - 默认情况下遵循 yaml:
- id: Foo
source: Bar
type: Connector
- id: Foo
source: Bar
type: Generator
将被解析为：
[Connector(Connector{...}), Generator(Generator{...})]
所以我的结构被包裹在枚举变体中。为了“打开它”，我想我可以实现 FromIterator<AllModels> for Vec<Box<dyn Model>> ，多亏了它并键入 conversion/coercion（不确定哪个是正确的词），输出更改为：
[Connector{...}, Generator{...}]
到目前为止还不错。
我在使用此解决方案时遇到的两个问题是：
- 代码重复 - 对于每个新结构（连接器，生成器，......）我必须更新
enum AllModels和matcharm insideFromIterator实现 - 后者是困扰我最我可能可以用宏来完成，但我还没有学会如何编写它们，在我这样做之前，我想探索其他可能的解决方案 - 额外迭代 - 为了从
Vec<enum variant>转换为Vec<struct>，我需要执行以下操作：let p: Vec<Box<dyn Model>> = serde_yaml::from_str::<Vec<AllModels>>(&data).unwrap().into_iter().collect();。我更愿意在没有额外迭代的情况下进行转换
我已经考虑了一些选项，但我不知道如何实施它们...
一个。 serde 容器属性 from/into docs
#[serde(from = "FromType")] - 我认为它的工作方式是将我的枚举变量直接强制转换为所需的结构，没有额外的迭代，也没有代码重复。但是，我未能实现它 - Playground.
当我尝试添加 from 属性时
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "type")]
enum AllModels {
Gene(Generator),
Connector(Connector),
}
编译器会骂我
❯ cargo r
Compiling serdeissue v0.1.0 (/sandbox/serdeissue)
error[E0277]: the trait bound `Box<dyn Model>: From<AllModels>` is not satisfied
--> src/main.rs:21:24
|
21 | #[derive(Debug, Clone, Serialize, Deserialize)]
| ^^^^^^^^^ the trait `From<AllModels>` is not implemented for `Box<dyn Model>`
|
= help: the following implementations were found:
<Box<(dyn StdError + 'a)> as From<E>>
<Box<(dyn StdError + 'static)> as From<&str>>
<Box<(dyn StdError + 'static)> as From<Cow<'a, str>>>
<Box<(dyn StdError + 'static)> as From<std::string::String>>
and 22 others
= note: required because of the requirements on the impl of `Into<Box<dyn Model>>` for `AllModels`
= note: required by `into`
= note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0277]: the trait bound `dyn Model: Serialize` is not satisfied
--> src/main.rs:21:24
|
21 | #[derive(Debug, Clone, Serialize, Deserialize)]
| ^^^^^^^^^ the trait `Serialize` is not implemented for `dyn Model`
|
::: /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/ser/mod.rs:247:18
|
247 | fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
| - required by this bound in `serialize`
|
= note: required because of the requirements on the impl of `Serialize` for `Box<dyn Model>`
= note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0277]: the trait bound `dyn Model: Deserialize<'_>` is not satisfied
--> src/main.rs:21:35
|
21 | #[derive(Debug, Clone, Serialize, Deserialize)]
| ^^^^^^^^^^^ the trait `Deserialize<'_>` is not implemented for `dyn Model`
|
::: /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/de/mod.rs:539:12
|
539 | D: Deserializer<'de>;
| ----------------- required by this bound in `_::_serde::Deserialize::deserialize`
|
= note: required because of the requirements on the impl of `Deserialize<'_>` for `Box<dyn Model>`
= note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0277]: the trait bound `AllModels: From<Box<dyn Model>>` is not satisfied
--> src/main.rs:21:35
|
21 | #[derive(Debug, Clone, Serialize, Deserialize)]
| ^^^^^^^^^^^ the trait `From<Box<dyn Model>>` is not implemented for `AllModels`
|
::: /home/marcin/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/convert/mod.rs:372:1
|
372 | pub trait From<T>: Sized {
| ------------------------ required by this bound in `From`
|
= note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
我的攻击角度如下：使用error msg to copy-pasteroni-dummy-implementoni missing trait bounds:
impl From<AllModels> for Box<dyn Model> {
fn from(am: AllModels) -> Self {
Box::new(Generator{id:String::from("arst"),source_id:String::from("arst")})
}
}
impl Serialize for dyn Model {
fn serialize(&self) -> Self {
Box::new(Generator{id:String::from("arst"),source_id:String::from("arst")})
}
}
impl Deserialize<'_> for dyn Model {}
impl From<Box<dyn Model>> for AllModels {
fn from(dm: Box<dyn Model>) -> Self {
AllModels::Gene(Generator{id:String::from("arst"),source_id:String::from("arst")})
}
}
但随后发生了这种情况：
❯ cargo r
Compiling serdeissue v0.1.0 (/sandbox/serdeissue)
error[E0277]: the size for values of type `(dyn Model + 'static)` cannot be known at compilation time
--> src/main.rs:75:6
|
75 | impl Deserialize<'_> for dyn Model {}
| ^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
|
::: /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/de/mod.rs:530:29
|
530 | pub trait Deserialize<'de>: Sized {
| ----- required by this bound in `Deserialize`
|
= help: the trait `Sized` is not implemented for `(dyn Model + 'static)`
对我来说游戏结束了
乙。 erased-serde
这似乎是完成这项工作的正确工具，但同样，我 运行 在实施它时遇到了问题（难怪 - 我不知道自己在做什么:)
use erased_serde::{Deserializer, Serializer, serialize_trait_object};
use serde::{Serialize, Deserialize};
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Generator {
id: String,
source: String,
}
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Connector {
id: String,
source: String,
}
trait Model: std::fmt::Debug + erased_serde::Serialize {}
erased_serde::serialize_trait_object!(Model);
impl Model for Generator {}
impl Model for Connector {}
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "type", into = "Box<dyn Model>", from = "Box<dyn Model>")]
enum AllModels {
Generator(Generator),
Connector(Connector),
}
fn main() {
let data = r#"
- source: "generator-01"
id: "g-01"
type: "Generator"
- source: "connector-01"
type: "Connector"
id: "c-01"
"#;
let p: Vec<Box<dyn Model>> = serde_yaml::from_str(&data).unwrap();
println!("{:?}", p);
}
impl From<AllModels> for Box<dyn Model> {
fn from(am: AllModels) -> Self {
Box::new(Generator{id:String::from("arst"),source_id:String::from("arst")})
}
}
// impl Serialize for dyn Model {
// fn serialize(&self) -> Self {
// Box::new(Generator{id:String::from("arst"),source_id:String::from("arst")})
// }
// }
impl Deserialize<'_> for dyn Model {}
impl From<Box<dyn Model>> for AllModels {
fn from(dm: Box<dyn Model>) -> Self {
AllModels::Generator(Generator{id:String::from("arst"),source_id:String::from("arst")})
}
}
// impl std::convert::From<AllModels> for Box<dyn Model> {
// fn from(m: AllModels) -> Self {
// Box::new(Generator {source_id: String::from("i"), id: String::from("r")})
// }
// }
我在编译时遇到这个错误：
❯ cargo r
Compiling serdeissue v0.1.0 (/sandbox/serdeissue)
warning: unused imports: `Deserializer`, `Serializer`, `serialize_trait_object`
--> src/main.rs:1:20
|
1 | use erased_serde::{Deserializer, Serializer, serialize_trait_object};
| ^^^^^^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^
|
= note: `#[warn(unused_imports)]` on by default
error[E0277]: the size for values of type `(dyn Model + 'static)` cannot be known at compilation time
--> src/main.rs:76:6
|
76 | impl Deserialize<'_> for dyn Model {}
| ^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
|
::: /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/de/mod.rs:530:29
|
530 | pub trait Deserialize<'de>: Sized {
| ----- required by this bound in `Deserialize`
|
= help: the trait `Sized` is not implemented for `(dyn Model + 'static)`
我认为 erased_serde 可以提供帮助，也许可以，但我不知道如何实施它。
遗憾的是我不能使用 typetag crate，因为它不支持我需要的 wasm 编译目标。我不考虑对每个枚举变体使用 #[serde(serialize_with = "path")]，因为它使我的问题 #1 比现在更糟。
我也知道这个问题
❯ cargo r
Compiling serdeissue v0.1.0 (/sandbox/serdeissue)
error[E0603]: module `export` is private
--> src/main.rs:168:10
|
168 | #[derive(Serialize)]
| ^^^^^^^^^ private module
|
note: the module `export` is defined here
--> /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/lib.rs:275:5
|
275 | use self::__private as export;
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0603]: module `export` is private
--> src/main.rs:173:10
|
173 | #[derive(Serialize)]
| ^^^^^^^^^ private module
|
note: the module `export` is defined here
--> /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/lib.rs:275:5
|
275 | use self::__private as export;
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0603]: module `export` is private
--> src/main.rs:179:10
|
179 | #[derive(Serialize)]
| ^^^^^^^^^ private module
|
note: the module `export` is defined here
--> /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/lib.rs:275:5
|
275 | use self::__private as export;
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0603]: module `export` is private
--> src/main.rs:184:10
|
184 | #[derive(Serialize)]
| ^^^^^^^^^ private module
|
note: the module `export` is defined here
--> /home/marcin/.cargo/registry/src/github.com-1ecc6299db9ec823/serde-1.0.123/src/lib.rs:275:5
|
275 | use self::__private as export;
| ^^^^^^^^^^^^^^^^^^^^^^^^^
warning: trait objects without an explicit `dyn` are deprecated
--> src/main.rs:176:22
|
176 | widgets: Vec<Box<WidgetTrait>>,
| ^^^^^^^^^^^ help: use `dyn`: `dyn WidgetTrait`
|
= note: `#[warn(bare_trait_objects)]` on by default
看来我正在寻找的功能正在等待在这里实现：https://github.com/serde-rs/serde/issues/1402
还有这个问题https://github.com/serde-rs/serde/issues/1350 which suggests manual Deserializer implementation Playground。游乐场代码表明这可以帮助解决我的问题 #2“额外迭代”，但是代码实现中仍然有一些重复，因此我仍在寻找更好的答案。
编辑：我也在考虑 Enum or trait object，无法确定评估我是否需要其中之一的正确方法。
我找到了一个令我满意的解决方案：
- 圆滑
- 无代码重复
- 没有动态调度，没有额外的迭代
- 使用
enum和serde(tag="...")type字段在 json/yaml 中可能是乱序的（不必是第一个）
序列化回 json/yaml
时包含 type字段
诀窍是使用 enum_dispatch。
use serde::{Serialize, Deserialize};
use enum_dispatch::enum_dispatch;
#[derive(Debug, Clone, Serialize, Deserialize)]
struct Generator {
source_id: String,
id: String,
}
#[derive(Debug, Clone, Serialize, Deserialize)]
struct Gate {
source_id: String,
id: String,
}
#[enum_dispatch]
trait Model {fn time_advance(self, a:i32,b:i32) -> i32;}
impl Model for Generator { fn time_advance(self,a:i32,b:i32) -> i32 {a+b} }
impl Model for Gate { fn time_advance(self,a:i32,b:i32) -> i32 {a+b} }
#[enum_dispatch(Model)]
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "type")]
enum ModelTypes {
Generator(Generator),
Gate(Gate),
}
fn main() {
let s = r#"
- source_id: "generator-01"
id: "connector-01"
type: "Generator"
- source_id: "geneiator-01"
type: "Gate"
id: "connector-01"
"#;
let data: Vec<ModelTypes> = serde_yaml::from_str(s).unwrap();
println!("{:?}", serde_yaml::to_string(&data));
for d in data {
println!("{:?}", d.time_advance(4, 2));
}
}
[package]
name = "enum_unpack"
version = "0.1.0"
authors = ["---"]
edition = "2018"
[dependencies]
serde = { version = "1.0.124", features = ["derive"] }
serde_yaml = "0.8.1"
enum_dispatch = "0.3.5"
输出：
> cargo run
Compiling enum_unpack v0.1.0 (.../enum_unpack)
Finished dev [unoptimized + debuginfo] target(s) in 0.66s
Running `target/debug/enum_unpack`
Ok("---\n- type: Generator\n source_id: generator-01\n id: connector-01\n- type: Gate\n source_id: geneiator-01\n id: connector-01\n")
6
6