Smart Contract Interactions with sdk-core JS library

Prerequisites

Before starting this tutorial, ensure the following software is installed on your machine:

Dependencies Used:

Dependency	Version	Purpose	Installation Link
Node.js	18.8.0	Runtime environment for executing JavaScript outside the browser.	Install Node.js
npm	9.8.1	Package manager for managing and installing JavaScript libraries.	Included with Node.js installation
TypeScript	5.1.6	Adds static types to JavaScript to enhance developer productivity and code quality.	Install TypeScript

You should also install and use NVM, to set a specific Node version in your project.

Once installed, you can use it like:

nvm use 18.18.0 

Steps

1. Create & set up ts-dapp-sdk-wire

mkdir -p ts-dapp-sdk-wire && cd ts-dapp-sdk-wire && npm init -y && npm install --save-dev [email protected] ts-node node-fetch && mkdir -p src && touch src/index.ts && touch .gitignore tsconfig.json && echo -e "node_modules/\ndist/" >> .gitignore

1.1. Add tsconfig.json

tsconfig.json

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "CommonJS",
    "lib": ["ES2022", "DOM"],
    "allowJs": true,
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,           
    "moduleResolution": "Node",
    "strict": false,                                    
    "outDir": "dist"
  }
}

1.2. Get your private key

Note your private key from the key pair generated earlier. You could output key pair value by running:

clio wallet private_keys --password=$(cat ~/my-secret-pass.txt)

1.3. Add scripts to package.json

Modify scripts in package.json to:

package.json

{
  "scripts": {
    "watch": "tsc -w",
    "exec": "node dist/index.js"
  }
}

2. Write the code

In this section, we will set up our application to interact with our local node from Company Contract Tutorial.

2.1. Initialize ApiClient()

index.ts

import { API, APIClient, FetchProvider, PrivateKey, SignedTransaction, Transaction, AnyAction, Action, PackedTransaction } from "@wireio/core";

const privateKey = "<your-private-key>"

const endpoint = "http://localhost:8888"


const apiClient = new APIClient(
  { provider: new FetchProvider(endpoint) }
);

API Client Initialization

• We import necessary modules like APIClient, FetchProvider, and transaction-related classes. You can see full SDK reference here.
• A private key is defined for signing transactions (make sure to replace it with your actual key).
• We specify the blockchain node’s API endpoint, in this case, a locally running node at http://localhost:8888.
• Finally, we initialize an instance of APIClient, which communicates with the blockchain via the FetchProvider, allowing us to interact with smart contracts for operations like signing and sending transactions.

Open up a terminal and run npm watch to run TypeScript compilation in watch mode. You should see the compiled dist folder.

2.2. Write API calls

---

Below is a breakdown of the API calls performed in the code snippet, along with the corresponding line numbers for each operation:

• Fetch Local Blockchain Info: Retrieves the current blockchain status. See line 14.
• Access Smart Contract Data: Fetches the current state of the employees table from the company smart contract, including the number of rows and user details. See line 20-28.
• Retrieve Contract ABI: Obtains and prints the ABI (Application Binary Interface) of the company smart contract, detailing its methods and structures. See line 36-39.
• Prepare Transaction: Constructs a transaction payload to update the details of an employee named “Jack” and constructs a signature required to authorize this transaction. See line 45-71.
• Execute Transaction: Sends the transaction to the blockchain. See line 73-76.

---

code

import { API, APIClient, FetchProvider, PrivateKey, SignedTransaction, Transaction, AnyAction, Action, PackedTransaction } from "@wireio/core";

const privateKey = "<your-private-key>"

const endpoint = "http://localhost:8888"


const apiClient = new APIClient(
  { provider: new FetchProvider(endpoint) }
);

(async () => {

    const info = await apiClient.v1.chain.get_info()
  
    console.log("\nBlockchain Info:");
    console.log(JSON.stringify(info, null, 2)); 
  
    // Retrieve rows from employees table in our company contract
    const tableRows: API.v1.GetTableRowsResponse = await apiClient.call({
        path: '/v1/chain/get_table_rows',
        params: {
          code: "company", 
          table: "employees",
          scope: "company",
          json: true
        },
    });

    console.log(tableRows)
  
    console.log(`\nEmployees Table Info:`);
    console.log(`- Number of rows: ${tableRows.rows.length}`);
    console.log(`- User emails: ${tableRows.rows.map(a => a.email).join(", ")}`);
  
    const abiRes: API.v1.GetAbiResponse = await apiClient.call({
      path: '/v1/chain/get_abi',
      params: {account_name: untypedAction.account},
    });

    const { abi } = abiRes;
    console.log("\nContract ABI:");
    console.log(JSON.stringify(abi, null, 2)); 

    const untypedAction: AnyAction =  {
        account: "company",
        name: "upsertemp",
        authorization: [
          {
            actor: "jack",
            permission: "active"
          }
        ],
        data: {
          user: "jack",
          name: "Jackson Smith!!",
          email: "[email protected]",
          status: "active"
        }
      }

      const action = Action.from(untypedAction, abi);
      const header = info.getTransactionHeader()

      const transaction = Transaction.from({ ...header, actions: [action] })
      const digest = transaction.signingDigest(info.chain_id)
      const privKey = PrivateKey.from(privateKey)

      const signature = privKey.signDigest(digest).toString()
      let signedTrx = SignedTransaction.from({ ...transaction, signatures: [signature] })
      const packed =  PackedTransaction.fromSigned(SignedTransaction.from(signedTrx));

      const trx = await apiClient.call({
        path: '/v1/chain/push_transaction',
        params: packed
      })
      console.log("\nTransaction Result:");
      console.log(JSON.stringify(trx, null, 2));
  
})();

3.Execute the code

You can inspect the employees table on the EOS Block Explorer before executing the script.

Run npm run exec and you should see output in the console with the logs like:

➜  ts-app-sdk-wire npm run
Blockchain Info:
{
  "server_version": "c83d8e08",
  "chain_id": "8a34ec7df1b8cd06ff4a8abbaa7cc50300823350cadc59ab296cb00d104d2b8f",
  "head_block_num": 538955,
  "last_irreversible_block_num": 538954,
  "last_irreversible_block_id": "0008394a52821c9552c17f8620576d53fe417e29068aee6ba6fe91b31591d052",
  "head_block_id": "0008394bd3b0ae2b818eed6a626ef66c3750a2a7cfff48e61f1bc6a8d5203076",
  "head_block_time": "2024-09-30T13:09:22.000",
  "head_block_producer": "sysio",
  "virtual_block_cpu_limit": 200000000,
  "virtual_block_net_limit": 1048576000,
  "block_cpu_limit": 200000,
  "block_net_limit": 1048576,
  "server_version_string": "v3.1.6",
  "fork_db_head_block_num": 538955,
  "fork_db_head_block_id": "0008394bd3b0ae2b818eed6a626ef66c3750a2a7cfff48e61f1bc6a8d5203076"
}
{
  rows: [
    {
      user: 'jack',
      name: 'Jackson Smith',
      ...
....

Check update on EOS Block Explorer