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Add try_mutate_exists to StorageDoubleMap. (#6694)

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Shaopeng Wang
2020-07-21 20:50:37 +12:00
committed by GitHub
parent 025c501766
commit c0179cb6e7
3 changed files with 57 additions and 1 deletions
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substrate/frame/support/src/storage/mod.rs
+7
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@@ -366,6 +366,13 @@ pub trait StorageDoubleMap<K1: FullEncode, K2: FullEncode, V: FullCodec> {
KArg2: EncodeLike<K2>,
F: FnOnce(&mut Self::Query) -> Result<R, E>;
/// Mutate the item, only if an `Ok` value is returned. Deletes the item if mutated to a `None`.
fn try_mutate_exists<KArg1, KArg2, R, E, F>(k1: KArg1, k2: KArg2, f: F) -> Result<R, E>
where
KArg1: EncodeLike<K1>,
KArg2: EncodeLike<K2>,
F: FnOnce(&mut Option<V>) -> Result<R, E>;
/// Append the given item to the value in the storage.
///
/// `V` is required to implement [`StorageAppend`].