abi: adding the method EventById and its test #19359
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accounts/abi/abi.go
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| // EventById looks up a event by the topic hash | ||
| // returns nil if none found | ||
| func (abi *ABI) EventById(topic common.Hash) (*Event, error) { |
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I see two issues with this approach:
- The only kind of error that can arise is that there are no event with this topic, which is not an error a priori. It's only an error if the calling code considers no event to be an error, but we shouldn't be making this assumption at this stage.
- If there are more than one event with a given topic, you will only be returning one.
As a result, I recommend returning a slice of pointers, i.e. :
func (abi *ABI) EventById(topic common.Hash) []*Event {There was a problem hiding this comment.
thx you for the review. First point makes complete sense to me.
However, on the second point, I think we can have at most one event per topic. The topic is the hash of the event name and arg types. Example from the test file, the topic is:
crypto.Keccak256Hash([]byte("received(address,uint256,bytes)"))therefore shouldn't be the mapping topic -> event unique ? I can't see how we could get multiple Event struct for a single topic (but having a collision).
accounts/abi/abi_test.go
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| {"indexed":false,"name":"amount","type":"uint256"}, | ||
| {"indexed":false,"name":"memo","type":"bytes"} | ||
| ] | ||
| }]` |
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so yeah please test with 0 event, 1 event and more than one event
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as I said in my previous comment, a topic has a single event and an event has a single topic (hash is unique).
My test already includes a case for
- event can be found
- event cannot be found
Co-authored-by: Victor Tran <vu.tran54@gmail.com>
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@salanfe good point, so in that case let me backtrack and let's keep the error field - I don't want to have a nil returned without some sort of warning.
There was a PR from @tranvictor who did the same thing, I have merged both in this one, and you are both attributed as an author of course. Thanks again for your work!
gballet
changed the title
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👍 great thx |
adding the method
EventByIdto the ABI, that allows to retrieve the event given a topic hash. Use case is similar to the methodMethodById: given a transactoionReceipt with a log slice and the contract ABI,EventByIdreturns the corresponding event "object" matching the log's topic field.