pub trait StorageMap<K: FullEncode, V: FullCodec> {
    type Query;

Show 17 methods // Required methods fn hashed_key_for<KeyArg: EncodeLike<K>>(key: KeyArg) -> Vec<u8> ; fn contains_key<KeyArg: EncodeLike<K>>(key: KeyArg) -> bool; fn get<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query; fn set<KeyArg: EncodeLike<K>>(key: KeyArg, query: Self::Query); fn try_get<KeyArg: EncodeLike<K>>(key: KeyArg) -> Result<V, ()>; fn swap<KeyArg1: EncodeLike<K>, KeyArg2: EncodeLike<K>>( key1: KeyArg1, key2: KeyArg2 ); fn insert<KeyArg: EncodeLike<K>, ValArg: EncodeLike<V>>( key: KeyArg, val: ValArg ); fn remove<KeyArg: EncodeLike<K>>(key: KeyArg); fn mutate<KeyArg: EncodeLike<K>, R, F: FnOnce(&mut Self::Query) -> R>( key: KeyArg, f: F ) -> R; fn try_mutate<KeyArg: EncodeLike<K>, R, E, F: FnOnce(&mut Self::Query) -> Result<R, E>>( key: KeyArg, f: F ) -> Result<R, E>; fn mutate_exists<KeyArg: EncodeLike<K>, R, F: FnOnce(&mut Option<V>) -> R>( key: KeyArg, f: F ) -> R; fn try_mutate_exists<KeyArg: EncodeLike<K>, R, E, F: FnOnce(&mut Option<V>) -> Result<R, E>>( key: KeyArg, f: F ) -> Result<R, E>; fn take<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query; fn append<Item, EncodeLikeItem, EncodeLikeKey>( key: EncodeLikeKey, item: EncodeLikeItem ) where EncodeLikeKey: EncodeLike<K>, Item: Encode, EncodeLikeItem: EncodeLike<Item>, V: StorageAppend<Item>; fn migrate_key<OldHasher: StorageHasher, KeyArg: EncodeLike<K>>( key: KeyArg ) -> Option<V>; // Provided methods fn decode_len<KeyArg: EncodeLike<K>>(key: KeyArg) -> Option<usize> where V: StorageDecodeLength { ... } fn migrate_key_from_blake<KeyArg: EncodeLike<K>>(key: KeyArg) -> Option<V> { ... }
}
Expand description

A strongly-typed map in storage.

Details on implementation can be found at [generator::StorageMap].

Required Associated Types§

source

type Query

The type that get/take return.

Required Methods§

source

fn hashed_key_for<KeyArg: EncodeLike<K>>(key: KeyArg) -> Vec<u8>

Get the storage key used to fetch a value corresponding to a specific key.

source

fn contains_key<KeyArg: EncodeLike<K>>(key: KeyArg) -> bool

Does the value (explicitly) exist in storage?

source

fn get<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query

Load the value associated with the given key from the map.

source

fn set<KeyArg: EncodeLike<K>>(key: KeyArg, query: Self::Query)

Store or remove the value to be associated with key so that get returns the query.

source

fn try_get<KeyArg: EncodeLike<K>>(key: KeyArg) -> Result<V, ()>

Try to get the value for the given key from the map.

Returns Ok if it exists, Err if not.

source

fn swap<KeyArg1: EncodeLike<K>, KeyArg2: EncodeLike<K>>( key1: KeyArg1, key2: KeyArg2 )

Swap the values of two keys.

source

fn insert<KeyArg: EncodeLike<K>, ValArg: EncodeLike<V>>( key: KeyArg, val: ValArg )

Store a value to be associated with the given key from the map.

source

fn remove<KeyArg: EncodeLike<K>>(key: KeyArg)

Remove the value under a key.

source

fn mutate<KeyArg: EncodeLike<K>, R, F: FnOnce(&mut Self::Query) -> R>( key: KeyArg, f: F ) -> R

Mutate the value under a key.

source

fn try_mutate<KeyArg: EncodeLike<K>, R, E, F: FnOnce(&mut Self::Query) -> Result<R, E>>( key: KeyArg, f: F ) -> Result<R, E>

Mutate the item, only if an Ok value is returned.

source

fn mutate_exists<KeyArg: EncodeLike<K>, R, F: FnOnce(&mut Option<V>) -> R>( key: KeyArg, f: F ) -> R

Mutate the value under a key.

Deletes the item if mutated to a None.

source

fn try_mutate_exists<KeyArg: EncodeLike<K>, R, E, F: FnOnce(&mut Option<V>) -> Result<R, E>>( key: KeyArg, f: F ) -> Result<R, E>

Mutate the item, only if an Ok value is returned. Deletes the item if mutated to a None. f will always be called with an option representing if the storage item exists (Some<V>) or if the storage item does not exist (None), independent of the QueryType.

source

fn take<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query

Take the value under a key.

source

fn append<Item, EncodeLikeItem, EncodeLikeKey>( key: EncodeLikeKey, item: EncodeLikeItem )where EncodeLikeKey: EncodeLike<K>, Item: Encode, EncodeLikeItem: EncodeLike<Item>, V: StorageAppend<Item>,

Append the given items to the value in the storage.

V is required to implement codec::EncodeAppend.

Warning

If the storage item is not encoded properly, the storage will be overwritten and set to [item]. Any default value set for the storage item will be ignored on overwrite.

source

fn migrate_key<OldHasher: StorageHasher, KeyArg: EncodeLike<K>>( key: KeyArg ) -> Option<V>

Migrate an item with the given key from a defunct OldHasher to the current hasher.

If the key doesn’t exist, then it’s a no-op. If it does, then it returns its value.

Provided Methods§

source

fn decode_len<KeyArg: EncodeLike<K>>(key: KeyArg) -> Option<usize>where V: StorageDecodeLength,

Read the length of the storage value without decoding the entire value under the given key.

V is required to implement StorageDecodeLength.

If the value does not exists or it fails to decode the length, None is returned. Otherwise Some(len) is returned.

Warning

None does not mean that get() does not return a value. The default value is completly ignored by this function.

source

fn migrate_key_from_blake<KeyArg: EncodeLike<K>>(key: KeyArg) -> Option<V>

Migrate an item with the given key from a blake2_256 hasher to the current hasher.

If the key doesn’t exist, then it’s a no-op. If it does, then it returns its value.

Implementors§

source§

impl<K: FullEncode, V: FullCodec, G: StorageMap<K, V>> StorageMap<K, V> for G

§

type Query = <G as StorageMap<K, V>>::Query