[SOLVED] How to get the account ID for a delegate action in a Near protocol contract?

How to get the account ID for a delegate action in a Near protocol contract?

I'm trying to use delegate actions with my contract.

From the contract's point of view it's irrelevant whether the action is in a standard transaction, or a delegate one. How can I get the relevant account ID whether the transaction is delegated or not?

I'm using Rust and near-sdk==4.1.1.

It seems that env::signer_account_id() in the contract's code returns the outer signer's id, rather than the underlying user's account id. The contract contains a check:

require!(env::signer_account_id() == owner, "ERR: not the owner");

which fails for the wrong reason with the following:

{'ActionError': {'index': 0, 'kind': {'FunctionCallError': {'ExecutionError': 'Smart contract panicked: ERR: not the owner'}}}}

Solution

I've read some more documentation and it seems that env::predecessor_account_id() is the answer. According to https://docs.near.org/build/smart-contracts/anatomy/environment:

Predecessor, env::predecessor_account_id(): Account ID that called this method
Signer, env::signer_account_id(): Account ID that signed the transaction leading to this execution.