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Hardhat 3 is now production ready. Migrate now
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#Extending the NetworkConnection

Let's start by adding the myAccount property to the NetworkConnection object returned by network.connect().

#Defining a network Hook Handler

To add a network property to the NetworkConnection object, we'll use a network Hook Handler.

The template already comes with the packages/plugin/src/hooks/network.ts file, so we'll replace its contents with this:

import type { HookContext, NetworkHooks } from "hardhat/types/hooks";
import { ChainType, NetworkConnection } from "hardhat/types/network";

export default async (): Promise<Partial<NetworkHooks>> => {
  const handlers: Partial<NetworkHooks> = {
    async newConnection<ChainTypeT extends ChainType | string>(
      context: HookContext,
      next: (nextContext: HookContext) => Promise<NetworkConnection<ChainTypeT>>
    ): Promise<NetworkConnection<ChainTypeT>> {
      const connection = await next(context);

      // Get the accounts from the connection
      const accounts: string[] = await connection.provider.request({
        method: "eth_accounts",
      });

      // Add the first account as myAccount for now
      connection.myAccount = accounts[0];

      return connection;
    },
  };

  return handlers;
};

The newConnection function above is a Hook Handler. Hardhat calls it every time a new network connection is created with network.connect().

Within this function, we first call next to call any other Hook Handler, or the default behavior of Hardhat. It returns the NetworkConnection object.

Then, we get the accounts of the connection and assign the first one as myAccount.

You'll get a type error in the highlighted line though. This is because the NetworkConnection type doesn't have a myAccount property.

We'll fix it by extending the NetworkConnection type.

#Extending the NetworkConnection type

The TypeScript type system lets you add properties to an existing type, what we call Type Extensions.

Open packages/plugin/src/type-extensions.ts, where you'll find something like this:

// More code above that you can ignore for now...

import "hardhat/types/network";
declare module "hardhat/types/network" {
  // eslint comments...
  interface NetworkConnection<
    // eslint comments...
    ChainTypeT extends ChainType | string = DefaultChainType
  > {
    // Add your network connection properties here
  }
}

We'll replace it with this:

// More code above that you can ignore for now...

import "hardhat/types/network";
declare module "hardhat/types/network" {
  interface NetworkConnection {
    myAccount: string;
  }
}

Extending the NetworkConnection type fixes the error from the previous section.

#Trying out your NetworkConnection extension

Let's try your extension out!

First, you need to build the plugin, by running this in packages/plugin:

pnpm build

Then, let's create a script in the example-project that uses your plugin.

Create the file packages/example-project/scripts/my-account-example.ts with this code:

import { network } from "hardhat";

const connection = await network.connect();

console.log("connection.myAccount:", connection.myAccount);

Run it from the example-project with this command:

pnpm hardhat run scripts/my-account-example.ts
Compiling your Solidity contracts...
Compiled 1 Solidity file with solc 0.8.29 (evm target: cancun)

connection.myAccount: 0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266