[英]Returning structure in Substrate RPC
我們試圖在 RPC 中返回結構,但據我所知它應該是可序列化的:
error[E0277]: the trait bound `pallet_spaces::Space<T>: serde::de::Deserialize<'_>` is not satisfied
--> pallets/spaces/rpc/src/lib.rs:15:1
|
15 | #[rpc]
| ^^^^^^ the trait `serde::de::Deserialize<'_>` is not implemented for `pallet_spaces::Space<T>`
|
= note: required because of the requirements on the impl of `for<'de> serde::de::Deserialize<'de>` for `std::vec::Vec<pallet_spaces::Space<T>>`
= note: required because of the requirements on the impl of `serde::de::DeserializeOwned` for `std::vec::Vec<pallet_spaces::Space<T>>`
= note: this error originates in an attribute macro (in Nightly builds, run with -Z macro-backtrace for more info)
問題是我們使用來自pallet_timestamp
的T::Moment
並且它不可序列化,所以我們停留在這一點上:
error[E0277]: the trait bound `<T as pallet_timestamp::Trait>::Moment: _::_serde::Serialize` is not satisfied
--> pallets/spaces/src/lib.rs:25:5
|
25 | pub created: WhoAndWhen<T>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `_::_serde::Serialize` is not implemented for `<T as pallet_timestamp::Trait>::Moment`
|
= note: required because of the requirements on the impl of `_::_serde::Serialize` for `pallet_utils::WhoAndWhen<T>`
= note: required by `_::_serde::ser::SerializeStruct::serialize_field`
您有什么建議可以輕松返回這樣的結構?
#[derive(Encode, Decode, Clone, Eq, PartialEq, RuntimeDebug, Serialize, Deserialize)]
pub struct Space<T: Trait> {
pub id: SpaceId,
pub created: WhoAndWhen<T>,
pub updated: Option<WhoAndWhen<T>>,
pub owner: T::AccountId,
// Can be updated by the owner:
pub parent_id: Option<SpaceId>,
pub handle: Option<Vec<u8>>,
pub content: Content,
pub hidden: bool,
pub posts_count: u32,
pub hidden_posts_count: u32,
pub followers_count: u32,
pub score: i32,
/// Allows to override the default permissions for this space.
pub permissions: Option<SpacePermissions>,
}
#[derive(Encode, Decode, Clone, Eq, PartialEq, RuntimeDebug, Serialize, Deserialize)]
pub struct WhoAndWhen<T: Trait> {
pub account: T::AccountId,
pub block: T::BlockNumber,
pub time: T::Moment,
}
您的主要問題是您在這里混合了std
和no-std
。 Substrate 僅依賴於std
模式下的serde
,正如您可以在項目中的任何Cargo.toml
文件中了解到的那樣。
從解決這個問題開始:當您處於std
模式時,您只能派生serde::*
。
#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
#[derive(Encode, Decode, Clone, Eq, PartialEq, RuntimeDebug)]
pub struct Space<T: Trait> {
// snip..
}
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