invokeTransferFrom() is problem in erc20 example

[TedKang]

Hi, I ran the erc20 example and it seems to be a problem with invokeTransferFrom().

allowance, err := getAllowance(c, fromMspId, fromCertId, invoker.GetMSPID(), invoker.GetID())

In the above code, the argument value corresponding to 'from' and the argument value position of 'invoker' seem to be reversed.

Please confirm.

Thanks

[vitiko]

// getAllowance gets amount of token allowed by wallet owner to spend by spender
func getAllowance(c r.Context, ownerMspId, ownerCertId, spenderMspId, spenderCertId string) (int, error) {
	return c.State().GetInt(allowanceKey(ownerMspId, ownerCertId, spenderMspId, spenderCertId), 0)
}

in the invokeTransferFrom() function

• invoker.GetMSPID() and invoker.GetID() are spender requisites
• fromMspId, fromCertId are wallet owner requisites

[TedKang]

// getAllowance gets amount of token allowed by wallet owner to spend by spender
func getAllowance(c r.Context, ownerMspId, ownerCertId, spenderMspId, spenderCertId string) (int, error) {
	return c.State().GetInt(allowanceKey(ownerMspId, ownerCertId, spenderMspId, spenderCertId), 0)
}

in the invokeTransferFrom() function

• invoker.GetMSPID() and invoker.GetID() are spender requisites
• fromMspId, fromCertId are wallet owner requisites

you're right. I mean, it would be the token owner to invoke transferFrom() in the code above. So I think the Invoker's MspId should be placed in ownerMspId when calling getAllowance ().

What i understood...

in the invokeTransferFrom() function

• invoker.GetMSPId(), invoker.GetId() >> token owner
• fromMspId, fromCertId >> token Sender

Please reply if I misunderstand.

[vitiko]

invokeTransferFrom() is invoked not by token owner, but by spender, who have allowance to spend some amount from token owner, so:

• invoker.GetMSPId(), invoker.GetId() - spender
• fromMspId, fromCertId - owner
• toMspId, toCertId - recipient

you can see example in test https://github.com/s7techlab/cckit/blob/master/examples/erc20/erc20_test.go#L101

[TedKang]

@vitiko Thanks for answer.
I misunderstood the concept.