My solidity:

contract Test {

    struct Num {
        uint value;

    function double(Num calldata num) external pure returns(Num memory) {
        return Num({ value: num.value * 2 });

My ethers:

await test.double(2); // doesn't work
await test.double([ 2 ]); // doesn't work
await test.double({ value: 2 }); // doesn't work
await test.double(ethers.BigNumber.from(2)); // doesn't work
await test.double([ ethers.BigNumber.from(2) ]); // doesn't work
await test.double({ value: ethers.BigNumber.from(2) }); // doesn't work

If I call a function that returns a Num type (with a value of 5 for example), I get:

  BigNumber { value: "5" },
  value: BigNumber { value: "5" }

So I also tried:

const params = [ ethers.BigNumber.from("2"), value: ethers.BigNumber.from("2") ]
await test.double(params);

But this doesn't even compile...

I also looked here: https://docs.ethers.io/v5/api/utils/abi/coder/#AbiCoder-decode

enter image description here

This seems to return the type of structure I need. So I also tried:

let params = ethers.utils.defaultAbiCoder.encode(
    [ 'uint value' ],
    [ 2 ]
params = ethers.utils.defaultAbiCoder.decode([ "uint value" ], params);
await test.double(params) // doesn't work

But this doesn't work either...


2 Answers 2


For struct, you use an object to insert argument:

const data = {
    value: 100,
const tx = await test.double(data);

I tried and got the output:

BigNumber { value: "200" }, 
value: BigNumber { value: "200" } 
  • Doesn't work for me. I get Error: call revert exception [ See: https://links.ethers.org/v5-errors-CALL_EXCEPTION ] (method="double((uint256))", errorArgs=null, errorName=null, errorSignature=null, reason=null, code=CALL_EXCEPTION, version=abi/5.6.0) Commented Oct 26, 2022 at 11:36
  • 2
    Actually, forget my last comment. That error was related to something else. Yes, your answer does work. Thanks! Commented Oct 26, 2022 at 14:27

If you are attempting to pass an argument to a struct, just try with square brackets, like so:

await contractName.functionFoo([exampleNumber]);

If a function returns a struct and you would like to interact with a key within it, you could also try:

let response = await contractName.functionFoo([exampleNumber])
// the number from the struct is now stored at response[0]

I recently wrote a contract that utilised structs and this is a snippet from my test file.

I hope I helped you, buddy! Keep hacking! :)

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