# Evidence Refactors

previous mention :

### [Evidence submission format](https://docs.kleros.io/developer/arbitration-development/erc-1497-evidence-standard#evidence)
- move to a stringified object in the Evidence event?
- move to event parameters: cheaper but harder to extend?
- hybrid: parameters + extra param stringified object

/// @title IEvidence
interface IEvidence {
    /// @dev To be raised when evidence is submitted.
    /// @param _externalDisputeID Unique identifier for this dispute outside Kleros. It's the submitter responsability to submit the right external dispute ID.
    /// @param _party The address of the party submiting the evidence. Note that 0x0 refers to evidence not submitted by any party.
    /// @param _evidenceTitle Title of the evidence.
    /// @param _evidenceBody Body of the evidence, in markdown format.
    /// @param _attachmentURI IPFS path to evidence, example: '/ipfs/QmZ5XaV2RVgBADq5qMpbuEwgCuPZdRgCeu8rhGtJWLV6yz.pdf'
    /// @param _attachmentContentType Content type of the attachment, example: 'application/pdf'
    /// @param _extraData Extra data stringified JSON encoded, reserved for future use.
    event Evidence(
        uint256 indexed _externalDisputeID,
        address indexed _party,
        string _evidenceTitle,
        string _evidenceBody,
        string _attachmentURI,
        string _attachmentContentType,
        string _extraData
    );
}

>:warning: The above is only from discussion about the refactors, no event changes will be made, only the evidence will be uploaded as stringified object now.

Against IPFS:
- easier to index
- easier/faster to fetch
- no upload needed (unless there's an attachment)

TBD: content type... should this be an input or can it be obtained from Filebase or derived
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type

> We now have a FileViewer that can infer the types itself, if however we ever need to infer type, we can use this library [file-type](https://www.npmjs.com/package/file-type)

## Changes to do
- Hopefully no major changes in contracts apart from updating natspecs
- Evidence would be passed as stringified object, the same way we pass dispute templates and item data in curate v2.

{
	"fileURI": "/ipfs/QmWQV5ZFFhEJiW8Lm7ay2zLxC2XS4wx1b2W7FfdrLMyQQc",
	"fileHash": "QmWQV5ZFFhEJiW8Lm7ay2zLxC2XS4wx1b2W7FfdrLMyQQc",	
	"fileTypeExtension": "pdf",
	"name": "Email clarifying the terms of the contract.",
	"description": "This is an email sent to Alice from Bob that clarifies that the recommendation page that was expected",
	"selfHash": "QmUQMJbfiQYX7k6SWt8xMpR7g4vwtAYY1BTeJ8UY8JWRs9"
}

> we will need to bring back self-hash since we wont have the ipfs hash to proove the integrity anymore.

>:warning: self hash not included yet in the PR.

Dapps affected :

- Court v2 : upload and fetch (updated in PR) :- https://github.com/kleros/kleros-v2/pull/1634
- curate v2 : upload and fetch (justification display)
- escrow v2 : upload only

- the natspec has been updated in contracts but not redeployed.
- once the contracts are redeployed, subgraphs will need to be redeployed.
- with the current contracts, nothing should crash, only the older evidences will not be fetched from ipfs like before