PY: Submit Post

Full, runnable src of Submit Post can be downloaded as part of: tutorials/python (or download just this tutorial: devportal-master-tutorials-python-10_submit_post.zip).

In this tutorial will explain and show you how to submit a new post to the Hive blockchain using the commit class found within the beem library.

Intro

The beem library has a built-in function to transmit transactions to the blockchain. We are using the transactionbuilder in the the library. It should be noted that comments and new post are both treated as the comment operation with the only difference being that a comment/reply has an additional parameter containing the parent_author/parent_permlink that corresponds to the original post/comment.

• author - The account that you are posting from
• title - The title of the post
• body - The body of the post
• permlink - A unique identifier, scoped to author
• parent_author - Empty string (for posts) or author being replied to (for replies)
• parent_permlink - Category (for posts) or permlink being replied to (for replies)
• json_metadata - JSON meta object that can be attached to the post
  • tags - Between 1 and 5 key words that defines the post

We will only be using the above parameters as these are the only ones required to create a basic post. If you want to explore the other parameters further you can find more information HERE.

Also see:

• comment_operation

Steps

1. App setup - Library install and import. Connection to Hive node
2. Variable input and format - Input and creation of varialbes
3. Post submission and result - Committing of transaction to the blockchain

1. App setup

In this tutorial we use the following packages:

• random and string - used to create a random string used for the permlink
• getpass - capture wif without showing it on the screen
• json - generate json_metadata
• beem - hive library and interaction with Blockchain

We import the libraries, connect to your local testnet, and initialize the Hive class.

import random
import string
import getpass
import json
from beem import Hive
from beem.transactionbuilder import TransactionBuilder
from beembase.operations import Comment

Because this tutorial alters the blockchain we have to connect to the testnet. We also require the private posting key of the contributing author in order to commit the post which is why we’re using a testnet node.

2. Variable input and format

The first three variables are captured via a simple string input while the tags variable is captured in the form of an array.

#capture variables
author = input('Username: ')
title = input('Post Title: ')
body = input('Post Body: ')

#capture list of tags and separate by " "
taglimit = 2 #number of tags 1 - 5
taglist = []
for i in range(1, taglimit+1):
  print(i)
  tag = input(' Tag : ')
  taglist.append(tag)

The tags parameter needs to be formatted within the json_metadata field as JSON. We also use a random generator to create a new permlink for the post being created.

#random generator to create post permlink
permlink = ''.join(random.choices(string.digits, k=10))

The random generator is limited to 10 characters in this case but the permlink can be up to 256 bytes. The permlink is unique to the author only which means that multiple authors can have the same permlink for the their post.

3. Post submission and result

The last step is to transmit the post through to the blockchain. All the defined parameters are signed and broadcasted. We also securely prompt for the posting key right before signing.

# client = Hive('https://testnet.openhive.network') # Public Testnet
client = Hive('http://127.0.0.1:8090') # Local Testnet
tx = TransactionBuilder(blockchain_instance=client)
tx.appendOps(Comment(**{
  "parent_author": '',
  "parent_permlink": taglist[0], # we use the first tag as the category
  "author": author,
  "permlink": permlink,
  "title": title,
  "body": body,
  "json_metadata": json.dumps({"tags": taglist})
}))

wif_posting_key = getpass.getpass('Posting Key: ')
tx.appendWif(wif_posting_key)
signed_tx = tx.sign()
broadcast_tx = tx.broadcast(trx_id=True)

print("Post created successfully: " + str(broadcast_tx))

A simple confirmation is printed on the screen if the post is committed successfully.

You can also check on your local testnet using database_api.find_comments for the post.

Try it

Click the play button below:

To Run the tutorial

You can launch a local testnet, with port 8090 mapped locally to the docker container:

docker run -d -p 8090:8090 inertia/tintoy:latest

For details on running a local testnet, see: Setting Up a Testnet

1. review dev requirements
2. git clone https://gitlab.syncad.com/hive/devportal.git
3. cd devportal/tutorials/python/10_submit_post
4. pip install -r requirements.txt
5. python index.py
6. After a few moments, you should see a prompt for input in terminal screen.