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JS: Get Account Comments

By the end of this tutorial you should know how to retrieve account comments from the crea blockchain

Full, runnable src of Get Account Comments can be downloaded as part of the JS tutorials repository.

This tutorial will show how to fetch comments made by a specific account (in this case @crearyblog) by demonstrating how to use the get_state api function call. We will also demonstrate the most commonly used fields from the response object as well as how to parse the body of each comment.

Intro

We are using the get_state function with dcrea that returns the current state of the network as well as additional content. Each content body is written in markdown and could be submitted to the blockchain by many different applications built on top of Crea. For that reason we are using the remarkable npm package to parse markdown in a readable format.

Steps

  1. App setup Configuration of dcrea to use the proper connection and network.
  2. Query Query the path which we want to extract from Crea blockchain state.
  3. Formatting Formatting the JSON object to be viewed in a simple user interface.

1. App setup

Below we have dcrea pointing to the main network with the proper chainId, addressPrefix and connection server. There is a public/app.js file which holds the Javascript segment of this tutorial. In the first few lines we define and configure library and packages.

const dcrea = require('dcrea');
let opts = {};
//connect to production server
opts.addressPrefix = 'STM';
opts.chainId =
    '0000000000000000000000000000000000000000000000000000000000000000';
//connect to server which is connected to the network/production
const client = new dcrea.Client('https://nodes.creary.net');

const Remarkable = require('remarkable');
const md = new Remarkable({ html: true, linkify: true });

remarkable is assigned to the variable md with linkify and html options, allowing us to parse markdown links and html properly.

2. Query

Next, we have the main function which runs when the page is loaded.

// query string, fetching comments made by @crearyblog account
const query = '/@crearyblog/comments';

client.database.call('get_state', [query]).then(result => {
    // work with state object
});

query is the path from where want to extract Crea blockchain state. In our example we are querying comments from the @crearyblog account. The result will be the current state object with various information as well as the content property holding the content of the query.

The following is an example of the returned object:

{
    "current_route":"/@crearyblog/comments",
    "props":{
        "head_block_number":22307429,
        "head_block_id":"01546265c9dc3e761add4c4b652743e3c640fa19",
        "time":"2018-05-10T12:15:30",
        "current_witness":"smooth.witness",
        "total_pow":514415,
        "num_pow_witnesses":172,
        "virtual_supply":"271970374.699 CREA",
        "current_supply":"268140818.508 CREA",
        "confidential_supply":"0.000 CREA",
        "current_sbd_supply":"13342173.771 CBD",
        "confidential_sbd_supply":"0.000 CBD",
        "total_vesting_fund_crea":"191002132.498 CREA",
        "total_vesting_shares":"388786707656.308148 VESTS",
        "total_reward_fund_crea":"0.000 CREA",
        "total_reward_shares2":"0",
        "pending_rewarded_vesting_shares":"366359809.533218 VESTS",
        "pending_rewarded_vesting_crea":"178575.754 CREA",
        "sbd_interest_rate":0,
        "sbd_print_rate":10000,
        "maximum_block_size":65536,
        "current_aslot":22373110,
        "recent_slots_filled":"340282366920938463463374607431768211455",
        "participation_count":128,
        "last_irreversible_block_num":22307411,
        "vote_power_reserve_rate":10,
        "average_block_size":14881,
        "current_reserve_ratio":200000000,
        "max_virtual_bandwidth":"264241152000000000000"
    },
    "tag_idx":{
        "popular":["","life","photography","creary","kr","introduceyourself","bitcoin","art","travel","cryptocurrency","spanish","food","crea","blog","funny","news","nature","colorchallenge","dtube","indonesia","story","cn","money","music","writing","crypto","contest","busy","health","poetry","meme","video","utopian-io","photo","new","love","blockchain","deutsch","dmania","science","technology","aceh","entertainment","gaming","politics","myanmar","ecrea","sports","fun","tr"]
    },
    "tags":{},
    "content":{
        "crearyblog/afm007-re-crearyblog-devportal-update-3-ux-improvements-more-javascript-tutorials-and-more-20180509t050215510z":{
            "id":47669989,
            "author":"crearyblog",
            "permlink":"afm007-re-crearyblog-devportal-update-3-ux-improvements-more-javascript-tutorials-and-more-20180509t050215510z",
            "category":"crea",
            "parent_author":"afm007",
            "parent_permlink":"devportal-update-3-ux-improvements-more-javascript-tutorials-and-more","title":"","body":"I want to learn the Python language.",
            "json_metadata":"{''}",
            "last_update":"2018-05-09T05:02:15",
            "created":"2018-05-09T05:02:15",
            "active":"2018-05-09T05:02:15",
            "last_payout":"1970-01-01T00:00:00",
            "depth":1,
            "children":0,
            "net_rshares":1057692008,
            "abs_rshares":1057692008,
            "vote_rshares":1057692008,
            "children_abs_rshares":0,
            "cashout_time":"2018-05-16T05:02:15",
            "max_cashout_time":"1969-12-31T23:59:59",
            "total_vote_weight":32523,
            "reward_weight":10000,
            "total_payout_value":"0.000 CBD",
            "curator_payout_value":"0.000 CBD",
            "author_rewards":0,
            "net_votes":1,
            "root_author":"crearyblog",
            "root_permlink":"devportal-update-3-ux-improvements-more-javascript-tutorials-and-more",
            "max_accepted_payout":"1000000.000 CBD",
            "percent_crea_dollars":10000,
            "allow_replies":true,
            "allow_votes":true,
            "allow_curation_rewards":true,
            "beneficiaries":[],
            "url":"/crea/@crearyblog/devportal-update-3-ux-improvements-more-javascript-tutorials-and-more#@afm007/afm007-re-crearyblog-devportal-update-3-ux-improvements-more-javascript-tutorials-and-more-20180509t050215510z",
            "root_title":"DevPortal Update #3: UX Improvements, More Javascript Tutorials and More!",
            "pending_payout_value":"0.005 CBD",
            "total_pending_payout_value":"0.000 CREA",
            "active_votes":[{"voter":"afm007","weight":17182,"rshares":1057692008,"percent":10000,"reputation":"855556264424","time":"2018-05-09T05:18:06"}],
            "replies":[],
            "author_reputation":"855556264424",
            "promoted":"0.000 CBD",
            "body_length":0,
            "reblogged_by":[]
        },
        "crearyblog/re-crearyblog-devportal-update-3-ux-improvements-more-javascript-tutorials-and-more-20180509t045305223z":{
            "id":47669080,
            "author":"crearyblog",
            "permlink":"re-crearyblog-devportal-update-3-ux-improvements-more-javascript-tutorials-and-more-20180509t045305223z",
            "category":"crea",
            "parent_author":"andreina89",
            "parent_permlink":"devportal-update-3-ux-improvements-more-javascript-tutorials-and-more",
            "title":"",
            "body":"Excellent post very interesting friend, thanks",
            "json_metadata":"{\"tags\":[\"crea\"],\"app\":\"creary/0.1\"}",
            "last_update":"2018-05-09T04:53:21",
            "created":"2018-05-09T04:53:21",
            "active":"2018-05-09T04:53:27",
            "last_payout":"1970-01-01T00:00:00",
            "depth":1,
            "children":1,
            "net_rshares":0,
            "abs_rshares":0,
            "vote_rshares":0,
            "children_abs_rshares":0,
            "cashout_time":"2018-05-16T04:53:21",
            "max_cashout_time":"1969-12-31T23:59:59",
            "total_vote_weight":0,
            "reward_weight":10000,
            "total_payout_value":"0.000 CBD",
            "curator_payout_value":"0.000 CBD",
            "author_rewards":0,
            "net_votes":0,
            "root_author":"crearyblog",
            "root_permlink":"devportal-update-3-ux-improvements-more-javascript-tutorials-and-more",
            "max_accepted_payout":"1000000.000 CBD",
            "percent_crea_dollars":10000,
            "allow_replies":true,
            "allow_votes":true,
            "allow_curation_rewards":true,
            "beneficiaries":[],
            "url":"/crea/@crearyblog/devportal-update-3-ux-improvements-more-javascript-tutorials-and-more#@andreina89/re-crearyblog-devportal-update-3-ux-improvements-more-javascript-tutorials-and-more-20180509t045305223z",
            "root_title":"DevPortal Update #3: UX Improvements, More Javascript Tutorials and More!",
            "pending_payout_value":"0.000 CBD",
            "total_pending_payout_value":"0.000 CREA",
            "active_votes":[],
            "replies":[],
            "author_reputation":"174938588721",
            "promoted":"0.000 CBD",
            "body_length":0,"reblogged_by":[]
        },
        {"etc.":"etc."}
    },
    "accounts":{
        "crearyblog:{
            "etc.":"etc."
        },
    },
    "witnesses":{},
    "discussion_idx":{},
    "witness_schedule":{
        "id":0,
        "current_virtual_time":"326078326927286190874576091",
        "next_shuffle_block_num":22307439,
        "current_shuffled_witnesses":["furion","someguy123","good-karma","blocktrades","smooth.witness"],
        "num_scheduled_witnesses":21,
        "top19_weight":1,
        "timeshare_weight":5,
        "miner_weight":1,
        "witness_pay_normalization_factor":25,
        "median_props":{
            "account_creation_fee":"0.100 CREA",
            "maximum_block_size":65536,
            "sbd_interest_rate":0
        },
        "majority_version":"0.19.3",
        "max_voted_witnesses":20,
        "max_miner_witnesses":0,
        "max_runner_witnesses":1,
        "hardfork_required_witnesses":17
    },
    "feed_price":{
        "base":"3.484 CBD",
        "quote":"1.000 CREA"
    },
    "error":""
}

3. Formatting

Next we will format the above object properly to view in a simple user interface. From the above object, we are only interested in the content object which holds the data we require.

if (
    !(
        Object.keys(result.content).length === 0 &&
        result.content.constructor === Object
    )
) {
    var comments = [];
    Object.keys(result.content).forEach(key => {
        const comment = result.content[key];
        const parent_author = comment.parent_author;
        const parent_permlink = comment.parent_permlink;
        const created = new Date(comment.created).toDateString();
        const body = md.render(comment.body);
        const netvotes = comment.net_votes;
        comments.push(
            `<div class="list-group-item list-group-item-action flex-column align-items-start">\
            <div class="d-flex w-100 justify-content-between">\
              <h6 class="mb-1">@${comment.author}</h6>\
              <small class="text-muted">${created}</small>\
            </div>\
            <p class="mb-1">${body}</p>\
            <small class="text-muted">&#9650; ${netvotes}, Replied to: @${parent_author}/${parent_permlink}</small>\
          </div>`
        );
    });
    document.getElementById('comments').style.display = 'block';
    document.getElementById('comments').innerHTML = comments.join('');
}

We first check if content is not an empty object. We then iterate through each object in content and extract:

We format created date and time, parse body markdown and get net_votes on that comment. Each line is then pushed and displayed separately.

To Run the tutorial

  1. clone this repo
  2. cd tutorials/09_get_account_comments
  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/