feat(cast): get logs

[bernard-wagner]

Motivation

It is often very useful to watch for events or get logs using specific topics.

Solution

Added a command that works in two ways.

cast logs --from-block 1234122 --to-block latest --address 0x0000000 SIG [ARGS]
cast logs --from-block 1234122 --to-block latest --address somename.eth TOPIC_0 [TOPICS]

Example:

cast logs --from-block 15537393 --to-block latest 'Transfer (address indexed from, address indexed to, uint256 value)' 0x2e8ABfE042886E4938201101A63730D04F160A82

- address: 0xdAC17F958D2ee523a2206206994597C13D831ec7
  blockHash: 0xa23f0f6f8cd60e489a5a9853b56dbef9deabe3cd41c03431e5cbc981a3c29581
  blockNumber: 16895421
  data: 0x0000000000000000000000000000000000000000000000000000000028fa46c3
  logIndex: 350
  removed: false
  topics: [
  	0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef
  	0x0000000000000000000000002e8abfe042886e4938201101a63730d04f160a82
  	0x000000000000000000000000e16dc9e130239d096d554a04ce6ddff5a78a774a
  ]
  transactionHash: 0xed77e9d350b15695f1d5e3a213c3aafee7055c422671e2779003f34cbebe1b19
  transactionIndex: 225
- address: 0xdAC17F958D2ee523a2206206994597C13D831ec7
  blockHash: 0x4e6b93493ce559a8264c82c8b3f8914c8ff0d381fd82c9e856c706d121c772b4
  blockNumber: 16895424
  data: 0x0000000000000000000000000000000000000000000000000000000000000000
  logIndex: 12
  removed: false
  topics: [
  	0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef
  	0x0000000000000000000000002e8abfe042886e4938201101a63730d04f160a82
  	0x000000000000000000000000e16adb7bcdf5df419fdd48cd092a058f68a4774a
  ]
  transactionHash: 0x3f83518d1b4d2b83f98df18c26dc3387731a50bf56421b9177b4a9f39a78f1eb
  transactionIndex: 12

Equivalent command using just topics:

cast logs --from-block 15537393 --to-block latest 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef 0x0000000000000000000000002e8abfe042886e4938201101a63730d04f160a82

Logic is that the signature of the event is TOPIC_0 anyways. So the position argument still is kind of consistent. The arguments for when specifying a signature are the indexed arguments of the signature and are converted to topic hashes.

I am still up skilling with Rust so opening a draft PR to get feedback while I work on adding some tests.

Also realised I still need to handle empty arguments (any) when using a signature.

[tynes]

It would be nice to have a --json flag to make it easy to pipe to jq, other commands have the --json flag

[tynes]

A few other thoughts:

• It would be nice to abi decode things, not sure if that should be the default behavior or behind a --pretty flag
• seth has the ability to watch for new logs, it probably uses eth_subscribe under the hood, not sure how useful that is in practice and probably adds complexity to the implementation

[bernard-wagner]

A few other thoughts:

• It would be nice to abi decode things, not sure if that should be the default behavior or behind a --pretty flag
• seth has the ability to watch for new logs, it probably uses eth_subscribe under the hood, not sure how useful that is in practice and probably adds complexity to the implementation

• The --json flag is already implemented.
• Think the --pretty makes a lot of sense to do decoding.
• Already created issues to support eth_subscribe: feat(cast): support websocket rpc urls #5022 feat(cast): eth_subscribe with optional decoding #5023. I expect that the build_filter logic implemented here could be reused. Does it make sense to add the helper functions to utils.rs so long?

[mattsse]

supportive, a few nits

[mattsse]

would like a one line here what this does: converting the BlockId

[bernard-wagner]

Renamed to convert_block_number to prevent overlap with existing functions in the repo. Also added a bit of documentation.

[mattsse]

I kinda know what this does, but this is difficult to understand.

we need a few docs here.

[bernard-wagner]

Split the logic into new functions and added some description, hopefully that makes it easier to follow.

[mattsse]

awesome!

this is now much easier to understand