Serde 尚不支持整数标签(请参阅问题 #745 https://github.com/serde-rs/serde/issues/745).
如果您能够更改生成数据的内容,那么如果您能够更改type
成一个字符串,即"1"
代替1
。然后你只需使用它就可以让它工作#[serde(rename)] https://serde.rs/field-attrs.html#rename.
#[derive(Debug, Serialize, Deserialize)]
#[serde(tag = "type")]
enum Message {
#[serde(rename = "1")]
T1(Type1),
#[serde(rename = "2")]
T2(Type2),
#[serde(rename = "3")]
T3(Type3),
// ...
}
如果这不是一个选项,那么您确实需要创建一个自定义解串器。就代码而言最短,很可能反序列化为serde_json::Value https://docs.serde.rs/serde_json/enum.Value.html,然后匹配type
, and 反序列化 the serde_json::Value
进入正确的Type{1,2,3}
.
use serde_json::Value;
impl<'de> serde::Deserialize<'de> for Message {
fn deserialize<D: serde::Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
let value = Value::deserialize(d)?;
Ok(match value.get("type").and_then(Value::as_u64).unwrap() {
1 => Message::T1(Type1::deserialize(value).unwrap()),
2 => Message::T2(Type2::deserialize(value).unwrap()),
3 => Message::T3(Type3::deserialize(value).unwrap()),
type_ => panic!("unsupported type {:?}", type_),
})
}
}
您可能想要执行一些适当的操作错误处理 https://serde.rs/error-handling.html,而不是打开包裹并惊慌失措。
如果您还需要序列化,那么您同样需要一个自定义序列化器。为此,您可以创建一个新类型来序列化,因为您不能使用Message
.
use serde::Serializer;
impl Serialize for Message {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
#[derive(Serialize)]
#[serde(untagged)]
enum Message_<'a> {
T1(&'a Type1),
T2(&'a Type2),
T3(&'a Type3),
}
#[derive(Serialize)]
struct TypedMessage<'a> {
#[serde(rename = "type")]
t: u64,
#[serde(flatten)]
msg: Message_<'a>,
}
let msg = match self {
Message::T1(t) => TypedMessage { t: 1, msg: Message_::T1(t) },
Message::T2(t) => TypedMessage { t: 2, msg: Message_::T2(t) },
Message::T3(t) => TypedMessage { t: 3, msg: Message_::T3(t) },
};
msg.serialize(serializer)
}
}
使用时#[serde(flatten)] https://serde.rs/field-attrs.html#flatten,然后它使用serde::private::ser::FlatMapSerializer https://github.com/serde-rs/serde/blob/8847800ce2cf404ae5f02485f030e380b246421e/serde/src/private/ser.rs#L1028,它在文档中是隐藏的。您可以使用以下方法来代替创建新类型SerializeMap https://docs.rs/serde/*/serde/ser/trait.SerializeMap.html and FlatMapSerializer
.
但是,请注意,鉴于它没有记录,那么任何未来版本的 serdecould如果您正在使用,请破坏您的代码FlatMapSerializer
直接地。
use serde::{private::ser::FlatMapSerializer, ser::SerializeMap, Serializer};
impl Serialize for Message {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
let mut s = serializer.serialize_map(None)?;
let type_ = &match self {
Message::T1(_) => 1,
Message::T2(_) => 2,
Message::T3(_) => 3,
};
s.serialize_entry("type", &type_)?;
match self {
Message::T1(t) => t.serialize(FlatMapSerializer(&mut s))?,
Message::T2(t) => t.serialize(FlatMapSerializer(&mut s))?,
Message::T3(t) => t.serialize(FlatMapSerializer(&mut s))?,
}
s.end()
}
}