Trait frame_support::storage::StorageDoubleMap

pub trait StorageDoubleMap<K1: FullEncode, K2: FullEncode, V: FullCodec> {
    type Query;

    // Required methods
    fn hashed_key_for<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Vec<u8> 
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>;
    fn contains_key<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> bool
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>;
    fn get<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Self::Query
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>;
    fn try_get<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Result<V, ()>
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>;
    fn set<KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>>(
        k1: KArg1,
        k2: KArg2,
        query: Self::Query
    );
    fn take<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Self::Query
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>;
    fn swap<XKArg1, XKArg2, YKArg1, YKArg2>(
        x_k1: XKArg1,
        x_k2: XKArg2,
        y_k1: YKArg1,
        y_k2: YKArg2
    )
       where XKArg1: EncodeLike<K1>,
             XKArg2: EncodeLike<K2>,
             YKArg1: EncodeLike<K1>,
             YKArg2: EncodeLike<K2>;
    fn insert<KArg1, KArg2, VArg>(k1: KArg1, k2: KArg2, val: VArg)
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>,
             VArg: EncodeLike<V>;
    fn remove<KArg1, KArg2>(k1: KArg1, k2: KArg2)
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>;
    fn remove_prefix<KArg1>(k1: KArg1, limit: Option<u32>) -> KillStorageResult
       where KArg1: ?Sized + EncodeLike<K1>;
    fn clear_prefix<KArg1>(
        k1: KArg1,
        limit: u32,
        maybe_cursor: Option<&[u8]>
    ) -> MultiRemovalResults
       where KArg1: ?Sized + EncodeLike<K1>;
    fn contains_prefix<KArg1>(k1: KArg1) -> bool
       where KArg1: EncodeLike<K1>;
    fn iter_prefix_values<KArg1>(k1: KArg1) -> PrefixIterator<V> 
       where KArg1: ?Sized + EncodeLike<K1>;
    fn mutate<KArg1, KArg2, R, F>(k1: KArg1, k2: KArg2, f: F) -> R
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>,
             F: FnOnce(&mut Self::Query) -> R;
    fn try_mutate<KArg1, KArg2, R, E, F>(
        k1: KArg1,
        k2: KArg2,
        f: F
    ) -> Result<R, E>
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>,
             F: FnOnce(&mut Self::Query) -> Result<R, E>;
    fn mutate_exists<KArg1, KArg2, R, F>(k1: KArg1, k2: KArg2, f: F) -> R
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>,
             F: FnOnce(&mut Option<V>) -> R;
    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>;
    fn append<Item, EncodeLikeItem, KArg1, KArg2>(
        k1: KArg1,
        k2: KArg2,
        item: EncodeLikeItem
    )
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>,
             Item: Encode,
             EncodeLikeItem: EncodeLike<Item>,
             V: StorageAppend<Item>;
    fn migrate_keys<OldHasher1: StorageHasher, OldHasher2: StorageHasher, KeyArg1: EncodeLike<K1>, KeyArg2: EncodeLike<K2>>(
        key1: KeyArg1,
        key2: KeyArg2
    ) -> Option<V>;

    // Provided method
    fn decode_len<KArg1, KArg2>(key1: KArg1, key2: KArg2) -> Option<usize>
       where KArg1: EncodeLike<K1>,
             KArg2: EncodeLike<K2>,
             V: StorageDecodeLength { ... }
}

An implementation of a map with a two keys.

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

Required Associated Types

type Query

The type that get/take returns.

Required Methods

fn hashed_key_for<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Vec<u8> where KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>,

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

fn contains_key<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> boolwhere KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>,

Does the value (explicitly) exist in storage?

fn get<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Self::Querywhere KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>,

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

fn try_get<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Result<V, ()>where KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>,

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

Returns Ok if it exists, Err if not.

fn set<KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>>( k1: KArg1, k2: KArg2, query: Self::Query )

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

fn take<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Self::Querywhere KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>,

Take a value from storage, removing it afterwards.

fn swap<XKArg1, XKArg2, YKArg1, YKArg2>( x_k1: XKArg1, x_k2: XKArg2, y_k1: YKArg1, y_k2: YKArg2 )where XKArg1: EncodeLike<K1>, XKArg2: EncodeLike<K2>, YKArg1: EncodeLike<K1>, YKArg2: EncodeLike<K2>,

Swap the values of two key-pairs.

fn insert<KArg1, KArg2, VArg>(k1: KArg1, k2: KArg2, val: VArg)where KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>, VArg: EncodeLike<V>,

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

fn remove<KArg1, KArg2>(k1: KArg1, k2: KArg2)where KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>,

Remove the value under the given keys.

fn remove_prefix<KArg1>(k1: KArg1, limit: Option<u32>) -> KillStorageResultwhere KArg1: ?Sized + EncodeLike<K1>,

👎Deprecated: Use clear_prefix instead

Remove all values under the first key k1 in the overlay and up to limit in the backend.

All values in the client overlay will be deleted, if there is some limit then up to limit values are deleted from the client backend, if limit is none then all values in the client backend are deleted.

Note

Calling this multiple times per block with a limit set leads always to the same keys being removed and the same result being returned. This happens because the keys to delete in the overlay are not taken into account when deleting keys in the backend.

fn clear_prefix<KArg1>( k1: KArg1, limit: u32, maybe_cursor: Option<&[u8]> ) -> MultiRemovalResultswhere KArg1: ?Sized + EncodeLike<K1>,

Remove all values under the first key k1 in the overlay and up to maybe_limit in the backend.

All values in the client overlay will be deleted, if maybe_limit is Some then up to that number of values are deleted from the client backend, otherwise all values in the client backend are deleted.

Cursors

The maybe_cursor parameter should be None for the first call to initial removal. If the resultant maybe_cursor is Some, then another call is required to complete the removal operation. This value must be passed in as the subsequent call’s maybe_cursor parameter. If the resultant maybe_cursor is None, then the operation is complete and no items remain in storage provided that no items were added between the first calls and the final call.

fn contains_prefix<KArg1>(k1: KArg1) -> boolwhere KArg1: EncodeLike<K1>,

Does any value under the first key k1 (explicitly) exist in storage? Might have unexpected behaviour with empty keys, e.g. [].

fn iter_prefix_values<KArg1>(k1: KArg1) -> PrefixIterator<V> where KArg1: ?Sized + EncodeLike<K1>,

Iterate over values that share the first key.

fn mutate<KArg1, KArg2, R, F>(k1: KArg1, k2: KArg2, f: F) -> Rwhere KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>, F: FnOnce(&mut Self::Query) -> R,

Mutate the value under the given keys.

fn try_mutate<KArg1, KArg2, R, E, F>(k1: KArg1, k2: KArg2, f: F) -> Result<R, E>where KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>, F: FnOnce(&mut Self::Query) -> Result<R, E>,

Mutate the value under the given keys when the closure returns Ok.

fn mutate_exists<KArg1, KArg2, R, F>(k1: KArg1, k2: KArg2, f: F) -> Rwhere KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>, F: FnOnce(&mut Option<V>) -> R,

Mutate the value under the given keys. 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>,

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.

fn append<Item, EncodeLikeItem, KArg1, KArg2>( k1: KArg1, k2: KArg2, item: EncodeLikeItem )where KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>, Item: Encode, EncodeLikeItem: EncodeLike<Item>, V: StorageAppend<Item>,

Append the given item to the value in the storage.

V is required to implement StorageAppend.

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.

fn migrate_keys<OldHasher1: StorageHasher, OldHasher2: StorageHasher, KeyArg1: EncodeLike<K1>, KeyArg2: EncodeLike<K2>>( key1: KeyArg1, key2: KeyArg2 ) -> Option<V>

Migrate an item with the given key1 and key2 from defunct OldHasher1 and OldHasher2 to the current hashers.

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

Provided Methods

fn decode_len<KArg1, KArg2>(key1: KArg1, key2: KArg2) -> Option<usize>where KArg1: EncodeLike<K1>, KArg2: EncodeLike<K2>, V: StorageDecodeLength,

Read the length of the storage value without decoding the entire value under the given key1 and key2.

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.

Implementors

impl<K1, K2, V, G> StorageDoubleMap<K1, K2, V> for Gwhere K1: FullEncode, K2: FullEncode, V: FullCodec, G: StorageDoubleMap<K1, K2, V>,

type Query = <G as StorageDoubleMap<K1, K2, V>>::Query