Let's look at the procedure for developing chaincode in Node.js:

• Create a Node.js file using the fabric-shim package
• Create a package.json file with the details of the Node.js file and dependencies, if any
• Package all the files in a ZIP file including package.json, the main Node.js file, and other JavaScript or config files or dependencies, if any
• Deploy the package under the Chaincode tab in OBP (refer to the Chaincode deployment section)

Sample Node.js file named education.js.

Create a Node.js file using the fabric-shim package:

const shim = require('fabric-shim');
const Chaincode = class {
    async Init(stub) {
        return shim.success();
    }
    async Invoke(stub) {
        let ret = stub.getFunctionAndParameters();
        let method = this[ret.fcn];
        console.log("Inside invoke. Calling method: " + ret.fcn);
        if (!method) {
            shim.error(Buffer.from('Received unknown function ' + ret.fcn + ' invocation'));
        }
        try {
            let payload = await method(stub, ret.params);
            return shim.success(payload);
        } catch (err) {
            console.log(err);
            return shim.error(err);
        }
    }

    //Method to save or update a user review to a product

    async insertReceiver(stub, args) {
        console.log("inside insertReceiver: " + JSON.stringify(args));
        if (args.length != 3) {
            throw 'Incorrect number of arguments. Expecting ID,Name and Org.';
        }
        var receiver = {};
                             receiver.ObjectType = "receiver";
        receiver.Receiver_id = args[0];
        receiver.Receiver_name = args[1];
        receiver.Upload_org = args[2];
        await stub.putState(receiver.Receiver_id, Buffer.from(JSON.stringify(receiver)));
    }//End of method
}

shim.start(new Chaincode());

Sample JSON file named package.json.

Create a package.json file with the details of the Node.js file and dependencies, if any:

{
  "name": "education",
  "version": "1.0.0",
  "description": "Chaincode implemented in node.js",
  "engines": {
    "node": ">=8.9.0",
    "npm": ">=5.5.0"
  }, 
  "scripts": { 
    "start" : "node education.js"
  },
  "engine-strict": true,
  "license": "Apache-2.0",
  "dependencies": { 
    "fabric-shim": "~1.3.0"
  } 
}

This sample Node.js code with the package.json file can be downloaded from the GitHub repository referenced in this book.