(authz) Keeper function to iterate all grant of granter

[taobun]

Summary

Problem Definition

We are looking to use authz module to authorize accounts to send msg for a validator. Logic to grant auth to account works well, but we cannot query all grants of the validator (list of all accounts of validator).

Proposal

I propose a new function in authz keeper

func (k Keeper) IterateGrantsOfGranter(ctx sdk.Context, granter sdk.AccAddress,
	handler func(granterAddr sdk.AccAddress, granteeAddr sdk.AccAddress, grant authz.Grant) bool) {
    store := ctx.KVStore(k.storeKey)
    iter := sdk.KVStorePrefixIterator(store, GrantKey + granter)
    ....
}

And we can create expect_keeper of this to use in our module to get all grants by a validator. If it possible to specific msgType , this should be good.

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[clevinson]

I think the idea would be to use the authz.keeper.Grants query method (it's also defined in the gRPC querier if you'd rather go through that route).

[taobun]

What I want is an endpoint to receive a granter address and return all grantees. But authz.keeper.Grants query that need granter and grantee to find all grants from this tuple. In keeper I only find IterateGrants function, but it need to iterate all grants in store, so I want we can add granter as prefix of iterator to list all value that has prefix of granter.

[taobun]

Any update on this @clevinson ?