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JS: Follow A User

Follow and unfollow a user / author.

Full, runnable src of Follow A User can be downloaded as part of the JS tutorials repository.

This tutorial will take you through the process of checking the follow status of an author and either follow or unfollow that user depending on the current status. This is done with the call operation as well as the broadcast.json operation.

Intro

We are using the broadcast.json operation provided by the dcrea library to follow or unfollow a selected author. There are 4 variables required to execute this operation:

  1. follower - The specific user that will select the author to follow/unfollow (username).
  2. privatekey - This is the private posting key of the user(postingKey).
  3. following - The account/author that the user would like to follow (author).
  4. what - The type of follow operation. This variable can have one of two values: blog, to follow an author, and a null value, unfollow the selected author.

A simple HTML UI is used to capture the required information, after which the broadcast operation can be compiled.

Steps

  1. Configure connection Configuration of dcrea to communicate with the Crea blockchain
  2. Input variables Collecting the required inputs via an HTML UI
  3. Get status Get the follow status for the specified author
  4. Follow operation Execute the follow operation

1. Configure connection

As usual, we have a public/app.js file which holds the Javascript segment of the tutorial. In the first few lines we define the configured library and packages:

import { Client, PrivateKey } from 'dcrea';
import { Testnet as NetConfig } from '../../configuration'; //A Crea Testnet. Replace 'Testnet' with 'Mainnet' to connect to the main Crea blockchain.

let opts = { ...NetConfig.net };

//connect to a crea node, testnet in this case
const client = new Client(NetConfig.url, opts);

Above, we have dcrea pointing to the test network with the proper chainId, addressPrefix, and endpoint by importing from the configuration.js file. Because this tutorial is interactive, we will not publish test content to the main network. Instead, we’re using the testnet and a predefined account which is imported once the application loads, to demonstrate following of an author.

window.onload = async () => {
    const account = NetConfig.accounts[0];
    const accountI = NetConfig.accounts[1];
    document.getElementById('username').value = account.address;
    document.getElementById('postingKey').value = account.privPosting;
    document.getElementById('author').value = accountI.address;
};

2. Input variables

The required parameters for the follow operation is recorded via an HTML UI that can be found in the public/index.html file.

The parameter values are allocated as seen below once the user clicks on the “Follow / Unfollow” button.

window.submitFollow = async () => {
    //get private key
    const privateKey = dcrea.PrivateKey.fromString(
        document.getElementById('postingKey').value
    );
    //get account name
    const follower = document.getElementById('username').value;
    //get author permalink
    const following = document.getElementById('author').value;

3. Get status

The current follow status for the author is called from the database and a variable is assigned in order to specify whether the follow operation should execute as follow or unfollow. For more information on this process you can refer to tutorial 19_get_follower_and_following_list.

console.log({ follower: follower, following: following });

    let status = await client.call('follow_api', 'get_following', [
        follower,
        following,
        'blog',
        1,
    ]);

    console.log({ status: status });

    if (status.length > 0 && status[0].following == following) {
        type = '';
    } else {
        type = 'blog';
    }

4. Follow operation

A JSON with the collected input variables is created in order for the data object within the broadcast operation to be completed.

const json = JSON.stringify([
    'follow',
    {
        follower: follower,
        following: following,
        what: [type], //null value for unfollow, 'blog' for follow
    },
]);

The broadcast.json operation requires a data object and private key in order the execute. For the follow/unfollow operation the variables in the object have predefined values. These values can change depending on the type of operation.

const data = {
    id: 'follow',
    json: json,
    required_auths: [],
    required_posting_auths: [follower],
};

The broadcast operation is then executed with the created object and the private posting key. We also display the follow status on the UI in order for the user to know the whether the process was a success.

client.broadcast.json(data, privateKey).then(
    function(result) {
        console.log('user follow result: ', result);
        document.getElementById('followResultContainer').style.display = 'flex';
        document.getElementById('followResult').className =
            'form-control-plaintext alert alert-success';
        if (type == 'blog') {
            document.getElementById('followResult').innerHTML =
                'Author followed';
        } else {
            document.getElementById('followResult').innerHTML =
                'Author unfollowed';
        }
    },
    function(error) {
        console.error(error);
        document.getElementById('followResultContainer').style.display = 'flex';
        document.getElementById('followResult').className =
            'form-control-plaintext alert alert-danger';
        document.getElementById('followResult').innerHTML = error.jse_shortmsg;
    }
);

If either of the values for the user or author does not exist the proper error result will be displayed on the UI. The result is also displayed in the console in order for the user to confirm that a block transaction has taken place. The status of the operation can be verified on the demo account.

To run this tutorial

  1. clone this repo
  2. cd tutorials/18_follow_user
  3. npm i
  4. npm run dev-server or npm run start
  5. After a few moments, the server should be running at http://localhost:3000/