json - 即使类型具有派生(序列化)，也不满足特征绑定(bind)序列化

Question

我正在尝试使用 serde 宏序列化 JSON，但我只收到此错误:

src/models/pulse.rs:89:28: 89:49 error: the trait bound `models::pulse::Pulse: serde::ser::Serialize` is not satisfied [E0277]
src/models/pulse.rs:89      if let Ok(bulk_string) = serde_json::to_string(&self) {
                                                     ^~~~~~~~~~~~~~~~~~~~~
src/models/pulse.rs:89:28: 89:49 help: run `rustc --explain E0277` to see a detailed explanation
src/models/pulse.rs:89:28: 89:49 note: required because of the requirements on the impl of `serde::ser::Serialize` for `&mut models::pulse::Pulse`
src/models/pulse.rs:89:28: 89:49 note: required by `serde_json::to_string`

我的代码好像没有什么问题。

#[derive(Serialize, Deserialize)]
pub struct Pulse {
    #[serde(skip_serializing_if="Option::is_none")]
    id: Option<u64>,

    #[serde(skip_serializing_if="Option::is_none")]
    category: Option<i64>,

    #[serde(skip_serializing_if="Option::is_none")]
    title: Option<String>,

}

是依赖错误吗？还是我的代码有问题？我用

[dependencies.serde]
git = "https://github.com/serde-rs/serde.git"
[dependencies.serde_macros]
git = "https://github.com/serde-rs/serde.git"
[dependencies.serde_json]
git = "https://github.com/serde-rs/json.git"

我有一个问题，为什么我使用 git 依赖项。原因是我得到:

/.cargo/registry/src/github.com-1ecc6299db9ec823/aster-

0.18.0/src/mac.rs:6:5: 6:39 error: unresolved import `syntax::feature_gate::GatedCfgAttr`. There is no `GatedCfgAttr` in `syntax::feature_gate`. Did you mean to use `GatedCfg`? [E0432]
/.cargo/registry/src/github.com-1ecc6299db9ec823/aster-0.18.0/src/mac.rs:6 use syntax::feature_gate::GatedCfgAttr;
                                                                                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/.cargo/registry/src/github.com-1ecc6299db9ec823/aster-0.18.0/src/mac.rs:6:5: 6:39 help: run `rustc --explain E0432` to see a detailed explanation
   Compiling num-traits v0.1.32
/.cargo/registry/src/github.com-1ecc6299db9ec823/aster-0.18.0/src/mac.rs:113:18: 113:81 error: this function takes 4 parameters but 5 parameters were supplied [E0061]
/.cargo/registry/src/github.com-1ecc6299db9ec823/aster-0.18.0/src/mac.rs:113     let mut cx = ExtCtxt::new(sess, cfg, ecfg, feature_gated_cfgs, macro_loader);
                                                                                                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/.cargo/registry/src/github.com-1ecc6299db9ec823/aster-0.18.0/src/mac.rs:113:18: 113:81 help: run `rustc --explain E0061` to see a detailed explanation
/.cargo/registry/src/github.com-1ecc6299db9ec823/aster-0.18.0/src/mac.rs:113:18: 113:81 note: the following parameter types were expected: &syntax::parse::ParseSess, std::vec::Vec<syntax::ptr::P<syntax::codemap::Spanned<syntax::ast::MetaItemKind>>>, syntax::ext::expand::ExpansionConfig<'_>, &mut syntax::ext::base::MacroLoader

我认为问题可能是您需要每晚使用。

Answer 1

从 rustc 1.20.0-nightly、serde 1.0.11 和 serde-json 1.0.2 开始，这段代码编译时没有问题。

附带说明一下，您确实应该使用 crates.io 依赖项而不是 git 依赖项。