# Keepers

The bank module provides three different exported keeper interfaces which can be passed to other modules which need to read or update account balances. Modules should use the least-permissive interface which provides the functionality they require.

Note that you should always review the bank module code to ensure that permissions are limited in the way that you expect.

# Common Types

# Input

An input of a multiparty transfer

Copy // Input models transaction input. message Input { string address = 1; repeated cosmos.base.v1beta1.Coin coins = 2; }

# Output

An output of a multiparty transfer.

Copy // Output models transaction outputs. message Output { string address = 1; repeated cosmos.base.v1beta1.Coin coins = 2; }

# BaseKeeper

The base keeper provides full-permission access: the ability to arbitrary modify any account's balance and mint or burn coins.

Copy // Keeper defines a module interface that facilitates the transfer of coins // between accounts. type Keeper interface { SendKeeper InitGenesis(sdk.Context, *types.GenesisState) ExportGenesis(sdk.Context) *types.GenesisState GetSupply(ctx sdk.Context) exported.SupplyI SetSupply(ctx sdk.Context, supply exported.SupplyI) GetDenomMetaData(ctx sdk.Context, denom string) types.Metadata SetDenomMetaData(ctx sdk.Context, denomMetaData types.Metadata) IterateAllDenomMetaData(ctx sdk.Context, cb func(types.Metadata) bool) SendCoinsFromModuleToAccount(ctx sdk.Context, senderModule string, recipientAddr sdk.AccAddress, amt sdk.Coins) error SendCoinsFromModuleToModule(ctx sdk.Context, senderModule, recipientModule string, amt sdk.Coins) error SendCoinsFromAccountToModule(ctx sdk.Context, senderAddr sdk.AccAddress, recipientModule string, amt sdk.Coins) error DelegateCoinsFromAccountToModule(ctx sdk.Context, senderAddr sdk.AccAddress, recipientModule string, amt sdk.Coins) error UndelegateCoinsFromModuleToAccount(ctx sdk.Context, senderModule string, recipientAddr sdk.AccAddress, amt sdk.Coins) error MintCoins(ctx sdk.Context, moduleName string, amt sdk.Coins) error BurnCoins(ctx sdk.Context, moduleName string, amt sdk.Coins) error DelegateCoins(ctx sdk.Context, delegatorAddr, moduleAccAddr sdk.AccAddress, amt sdk.Coins) error UndelegateCoins(ctx sdk.Context, moduleAccAddr, delegatorAddr sdk.AccAddress, amt sdk.Coins) error MarshalSupply(supplyI exported.SupplyI) ([]byte, error) UnmarshalSupply(bz []byte) (exported.SupplyI, error) types.QueryServer }

# SendKeeper

The send keeper provides access to account balances and the ability to transfer coins between accounts, but not to alter the total supply (mint or burn coins).

Copy // SendKeeper defines a module interface that facilitates the transfer of coins // between accounts without the possibility of creating coins. type SendKeeper interface { ViewKeeper InputOutputCoins(ctx sdk.Context, inputs []types.Input, outputs []types.Output) error SendCoins(ctx sdk.Context, fromAddr sdk.AccAddress, toAddr sdk.AccAddress, amt sdk.Coins) error SubtractCoins(ctx sdk.Context, addr sdk.AccAddress, amt sdk.Coins) error AddCoins(ctx sdk.Context, addr sdk.AccAddress, amt sdk.Coins) error SetBalance(ctx sdk.Context, addr sdk.AccAddress, balance sdk.Coin) error SetBalances(ctx sdk.Context, addr sdk.AccAddress, balances sdk.Coins) error GetParams(ctx sdk.Context) types.Params SetParams(ctx sdk.Context, params types.Params) SendEnabledCoin(ctx sdk.Context, coin sdk.Coin) bool SendEnabledCoins(ctx sdk.Context, coins ...sdk.Coin) error BlockedAddr(addr sdk.AccAddress) bool }

# ViewKeeper

The view keeper provides read-only access to account balances but no balance alteration functionality. All balance lookups are O(1).

Copy // ViewKeeper defines a module interface that facilitates read only access to // account balances. type ViewKeeper interface { ValidateBalance(ctx sdk.Context, addr sdk.AccAddress) error HasBalance(ctx sdk.Context, addr sdk.AccAddress, amt sdk.Coin) bool GetAllBalances(ctx sdk.Context, addr sdk.AccAddress) sdk.Coins GetAccountsBalances(ctx sdk.Context) []types.Balance GetBalance(ctx sdk.Context, addr sdk.AccAddress, denom string) sdk.Coin LockedCoins(ctx sdk.Context, addr sdk.AccAddress) sdk.Coins SpendableCoins(ctx sdk.Context, addr sdk.AccAddress) sdk.Coins IterateAccountBalances(ctx sdk.Context, addr sdk.AccAddress, cb func(coin sdk.Coin) (stop bool)) IterateAllBalances(ctx sdk.Context, cb func(address sdk.AccAddress, coin sdk.Coin) (stop bool)) }