Feature: auto-generated types for solidity structs and events

• “ethers”: “5.3.0”

• “@typechain/ethers-v5”: “7.0.0”

• “typechain”: “5.0.0”

Typechain is generating this for a solidity function that is accepting a struct as input and also returns an array of structs as output:

Solidity:

struct CanExecData {
    uint256 id;
    address user;
    uint256 minimumHF;
    address colToken;
    address spender;
}

struct CanExecResult {
    uint256 id;
    string isPositionSafe;
    string isATokenAllowed;
    string message;
}

    function multiCanExecute(CanExecData[] memory _canExecDatas)
        external
        view
        returns (CanExecResult[] memory)

Typechain:

  multiCanExecute(
    _canExecDatas: {
      id: BigNumberish;
      user: string;
      minimumHF: BigNumberish;
      colToken: string;
      spender: string;
    }[],
    overrides?: CallOverrides
  ): Promise<
    ([BigNumber, string, string, string] & {
      id: BigNumber;
      isPositionSafe: string;
      isATokenAllowed: string;
      message: string;
    })[]
  >;

It would be really useful if typechain also generated and exported interface for every solidity struct with correct field names.

Otherwise we have to resort to defining those types ourselves:

// DO NOT MODIFY FIELDS: must match solidity struct
export interface CanExecData {
  id: string;
  user: string;
  minimumHF: BigNumber;
  colToken: string;
  spender: string;
}

// DO NOT MODIFY FIELDS: must match function return type
export interface CanExecResult {
  id: string;
  isPositionSafe: string;
  isATokenAllowed: string;
  message: string;
}

And then do an unsafe cast via unknown to those types:

export const multiCanExecute = async (
  canExecDatas: CanExecData[]
): Promise<CanExecResult[]> => {
  return refinanceResolver.multiCanExecute(
    canExecDatas
  ) as unknown as CanExecResult[];
};

I suppose that if typechain correctly auto-generates the CanExecResult struct type, then the cast via unknown would not be necessary because it intersects in the ethers.js function result type

Promise<
    ([BigNumber, string, string, string] & {
      id: BigNumber;
      isPositionSafe: string;
      isATokenAllowed: string;
      message: string;
    })[]
  >

Maybe typechain could also make use of the auto-generated struct type internally in its definitions like so (if it doesnt cause trouble with ethers.js compatibility)?

 multiCanExecute(
   _canExecDatas: CanExecData[],
   overrides?: CallOverrides
 ): Promise<
   ([BigNumber, string, string, string] & CanExecResult)[]
 >;

Either way it would be super useful if typechain also auto-generated and exported types for Solidity structs, to avoid human error.

The same can be said for solidity events.

Thanks for this amazing tool @krzkaczor ! We use it every day and love it!

[krzkaczor]

@zemse pointed out that sometimes structs appear in abi 👏

I did some testing and it appears that:

• "internalType": "struct StructName" will be generated if the struct is used as input or output of an exposed method
• will NOT appear if structs are only used internally or only in public storage variables (this case is quite unexpected)

[krzkaczor]

Support for events released in https://github.com/dethcrypto/TypeChain/releases/tag/%40typechain%2Fethers-v5%407.1.0

h/t @zemse