Cannot call contract methods using Cloudflare Workers

[larskoole]

Ethers Version

6.0.2

Search Terms

cloudflare, code generation, Code generation from strings disallowed for this context

Describe the Problem

When using CloudFlare Workers I can't call methods on a contract.
A simple await contract.balanceOf(wallet.address).call() doesn't work in my case.

The error I get is Code generation from strings disallowed for this context.

Ideally, this would get solved in the package itself (if it is even related to an internal bug).
Otherwise, if I need to use a workaround that would be totally fine too.

Code Snippet

const { JsonRpcProvider, Contract, Wallet, formatEther } = await import('ethers');

const abi = ['function balanceOf(address account) external view returns (uint)'];
const provider = new JsonRpcProvider("https://polygon-rpc.com");
const wallet = new Wallet(env.PRIVATE_KEY, provider);
const contract = new Contract("someAddress", abi, provider);

const result = await contract.balanceOf(wallet.address).call()

Contract ABI

['function balanceOf(address account) external view returns (uint)']

Errors

✘ [ERROR] Uncaught (in promise) EvalError: Code generation from strings disallowed for this context

  super();
  ^
      at WrappedMethod
  (/Users/redacted/redacted/redacted/node_modules/ethers/src.ts/contract/contract.ts:250:8)
      at getFunction
  (/Users/redacted/redacted/redacted/node_modules/ethers/src.ts/contract/contract.ts:767:28)
      at get
  (/Users/redacted/redacted/redacted/node_modules/ethers/src.ts/contract/contract.ts:705:38)

Environment

Other (please specify)

Environment (Other)

CloudFlare Workers

[ricmoo]

That line is a call to super(). Are you using a bundler that could be mangling the code? What node version is being used on the host?

[larskoole]

I've set the version to 17.9.1 but I don't have any control over how it's built.

[ricmoo]

Cloudflare Workers must be built on a separate host, and then uploaded, since the service only accepts a single-file application (unless there have been recent changes?), so there must be a bundler config (web pack or rollup) somewhere...

[larskoole]

Then it's as default as it comes haha.
Is there anything I can do to test a solution?

[larskoole]

The following pages goes over the bundling of a worker using the latest version of wrangler:
https://developers.cloudflare.com/workers/wrangler/bundling

Maybe there is a setting I can try/tweak.

[ricmoo]

Is there any way you can see the generated code?

[larskoole]

Yes, but I'd rather not post it here publicly.
Is there a way to DM you?

[larskoole]

You could also reproduce it by creating a project with Wrangler and use the following code/settings:

File: index.js

export default
{
	async fetch(request, env, ctx)
	{
		const { JsonRpcProvider, Contract, Wallet, formatEther } = await import('ethers');

		const CONTRACT = {
			address: "someAddressHere",
			abi: [
				'function balanceOf(address account) external view returns (uint)'
			]
		}

		// Provider and wallet
		const provider = new JsonRpcProvider(env.RPC_URL);
		const wallet = new Wallet(env.PRIVATE_KEY, provider);
		const contract = new Contract(CONTRACT.address, CONTRACT.abi, provider);

		const result = await contract.balanceOf(wallet.address).call();

		console.log(result);
	},
};

File: wrangler.toml

name = "whatever"
main = "src/index.js"
compatibility_date = "2023-02-09"

[vars]
RPC_URL = "https://rpc-mainnet.matic.quiknode.pro"
NODE_VERSION = "17.9.1"

And using wrangler publish --dry-run --outdir dist to output the generated code to a directory called dist.

[ricmoo]

I've got a few other things that are high priority I'm working on now, but you can send me an e-mail to me@ricmoo.com. If you can produce a small concise example with the generated code, that's always appreciated too. ;)

[larskoole]

I'll send you the generated code for the example above!
Thanks for helping so far :)

[larskoole]

Quick side note. I've downgraded to the latest v5 version and that one does work, so maybe that narrows the search for the bug. Let me know if you need a copy of the generated code.

[ricmoo]

This is the same problem as #3749, which I’ve been updating, so I’m going to close this issue to help keep all the discussion in one place.

I’m pretty sure I understand the problem now and will get v6.2.0 out asap to address this.

Thanks! :)

[ricmoo]

This has been addressed in v6.2.0. Please try it out and let me know if there are any problems. :)