Question

我正在尝试使用通用成员序列化结构，但由于sns_pub::_IMPL_DESERIALIZE_FOR_Message::_serde::Serialize对sns_pub::Message<T>的隐含要求而导致出现错误'

#[derive(Debug, PartialEq, Serialize, Deserialize)]
#[serde(bound(
serialize = "T: Serialize",
deserialize = "T: Deserialize<'de>",
))]
struct Message<T> {
    topic: String,
    message_id: String,
    created_date: DateTime<Utc>,
    message: T,
    subject: String
}
let msg = String::from("TEST_MESSAGE"); 
let message = Message {
             topic: self.topic.clone(),
             message_id: id.to_string(),
             created_date: now,
             subject: self.subject.clone(),
             message: msg
         };
let filename = format!("{}/{}_{}", self.folder_path, prefix, id);
let mut file = File::create(filename.clone())?;
 file.write_all(serde_yaml::to_string(&message)?.as_str())?;

error[E0277]: the trait bound `T: sns_pub::_IMPL_DESERIALIZE_FOR_Message::_serde::Serialize` is not satisfied
    --> src/sns_pub.rs:57:46
    | 
43  | impl<T> SnsPub<T> for DiskSnsPub {
    |      - help: consider restricting this bound: `T: sns_pub::_IMPL_DESERIALIZE_FOR_Message::_serde::Serialize` ... 
57  |  file.write_all(serde_yaml::to_string(&message)?.as_str())?;
    |                                       ^^^^^^^^ the trait `sns_pub::_IMPL_DESERIALIZE_FOR_Message::_serde::Serialize` is not implemented for `T`
    |     ::: /home/moharaza/.cargo/registry/src/github.com-1ecc6299db9ec823/serde_yaml-0.8.11/src/ser.rs:421:8
    | 
421 |     T: ser::Serialize,
    |              -------------- required by this bound in `serde_yaml::ser::to_string`
    |
    = note: required because of the requirements on the impl of `sns_pub::_IMPL_DESERIALIZE_FOR_Message::_serde::Serialize` for `sns_pub::Message<T>`

error[E0308]: mismatched types

Answer 1

提供的代码缺少很多信息，而错误实际上是由您未提供的代码引起的。这就是为什么提供[reprex]很重要的原因。

但是，我可以猜到其中的某些代码实际上来自Message方法，因为它使用self。您错过的只是定义该方法的impl块的边界T：

impl<T> Message<T>
where
    T: Serialize + for<'de> Deserialize<'de>,
{
     /// methods go here 
{

我知道这一点，因为错误消息已经完全告诉您了。

我将特征绑定到`T：sns_pub :: __ IMPL_DESERIALIZE_FOR_Message :: _ serde :: Serialize`不满意

1 个答案: