Hello World!

This guide describes how to create your first basic contract and try it with test blockchain using XPR Network.

Let's start!

Pre-requisites

• NodeJS 16 Installation Guide (opens new window)
• NPM
• Git
• XPR Network CLI (opens new window)

  npm install -g @proton/cli
  

Steps

1. Generate a contract by providing a contract name, as shown here:

proton generate:contract helloworld

Note: the contract name must be 1-12 chars, only lowercase a-z and numbers 1-5 are possible.

2. The proton generate:contract command prompts you for information about the action of the contact: name and parameters. Let's add action say with text parameter that is string:

   Let's add some actions to the class
   ? Enter new action name: say
   ? Do you want to add parameters to the action? Yes
   ? Enter new parameter name: text
   ? Choose parameter type: string
   ? Is the parameter an array? No
   ? Can the parameter be nullable? No
   ————————————
   ? Do you want to add one more parameter? No
   ————————————
   ? Do you want to add one more action? No
   
   

3. The command will prompt you to select your favorite Node.Js package manager if you have both npm and yarn installed. Feel free to select the one you like.

4. After the contract is ready navigate to helloworld folder. The folder will have the following structure:

   Files	Details
   helloworld.contract.ts	The contract code, written in XPR Network
   playground.ts	The code to try a contract

5. Open helloworld.contract.ts file. It should look like this:

   import { Contract } from "proton-tsc";
   
   @contract
   export class helloworld extends Contract {
   
       @action("say")
       say(
           text: string
       ): void {
           // Add code of your contract here
       }
   }
   

6. Let's modify the contract to print your name. Import print function from proton-tsc:

   import { Contract, print } from "proton-tsc";
   

7. And add the call of the function to the say method instead of // Add here a code of your contract statement:

   @action("say")
   say(
       text: string
   ): void {
       print(`Hello, ${text}`);
   }
   

8. Open playground.ts file. It should look like this:

   import { Blockchain } from "@proton/vert";
   
   async function wait(ms: number) {
       return new Promise(resolve => {
           setTimeout(resolve, ms);
       });
   }
   
   async function main() {
       const blockchain = new Blockchain();
       const contract = blockchain.createContract('helloworld', 'target/helloworld.contract');
       await wait(0);
   
       // Put you actions calls here
       await contract.actions.say(['']).send('helloworld@active');
   }
   
   main();
   

9. Let's modify it adding World! instead of empty line:

   await contract.actions.say(['World!']).send('helloworld@active');
   

10. Now we can run the playground and check how it works:

    npm run playground
    

    The result should be the following:

    DEBUG:
    
    START ACTION
    Contract: helloworld
    Action: say
    Inline: false
    Notification: false
    First Receiver: helloworld
    Sender:
    Authorization: [{"actor":"helloworld","permission":"active"}]
    Data: {
        "text": "World!"
    }
    Action Order: 0
    Execution Order: 0
    
    DEBUG: action_data_size
    DEBUG: read_action_data
    DEBUG: prints_l Hello, World!
    

As you can see, the last line displays the result of print function.

Congrats, you just created your first contract!