Part 10: Use Urls To Retrieve Post Data And Construct A Dynamic Post With Steem-Python

This tutorial is part of a series where we explain different aspects of programming with steem-python. Links to the other tutorials can be found in the curriculum section below. This part will focus on how to use urls to retrieve data from the Steem blockchain and construct a post.

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What will I learn

• How to copy multiple urls from your browser
• Construct a permlink from a url
• Retrieve post data from the blockchain
• Construct a dynamic post

Requirements

• Python3.6
• steem-python

Difficulty

• Basic

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Tutorial

Setup

Start by downloading the files from Gitub. For this tutorial there are 2 files. A textfile in which the urls are stored and the python script itself. For this example we will be constructing a post for the winners of a photography contest. From each post we want to retrieve the title, author and the winning photo.

winners.txt

https://steemit.com/landscapephotography/@rinawonderlands/every-mountain-top-is-within-reach-if-you-just-keep-climbing
https://steemit.com/landscapephotography/@uadigger/5peq5n-winter-in-the-carpathians 2
https://steemit.com/landscapephotography/@matajingga/landscape-photography-mount-batok 1

As some authors post multiple photos in an article there is a second variable which indicates the index of the photo to retrieve. The setup is then like: <url> <photo_index> where the standard photo_index is set to 0.

Run the script by with the filename as the first argument
> python main.py winners.txt

Copying multiple urls from your browser

Copy All Urls is a chrome browser extension that allows you to copy all your open tab urls. Perfect when dealing with a large amount of urls.

Constructing the permlink

The unique link for each post, the permlink, can be constructed by removing everything before the @. It does not matter from which platform you take the link. It works for all platforms, for example steemit.com or busy.org

<platform url>/@<permlink>

Retrieve post data from the blockchain

The permlink can then be used to construct a Post object from which all the data can be retrieved.

from steem.post import Post

post = Post(permlink)

Using post.export() will retrieve all the data from the post. As can be seen here that is a lot of data. The title and author are immediately accessible. While the images are stored underjson_metadata

This is were the photo_index is used to retrieve the correct image from ['json_metadata']['image']

Construct a dynamic post

By constructing a post from a header, body and a footer a dynamic post can be constructed where the length varies depending on the input.

header = "<center>\n# Test selection\n***\n"
body = ""
footer = "End of test selection\n</center>"

for each url:
     body += "Title: {}<br>Author: @{}<br>Permlink: {}<br>Image:{}\n***\n".format(title, author, permlink, image)


post = header + body + footer

Running the code

Using the accompanied winners.txt file will generate a post containing the 3 photos with the relevant title, author and permlink. Feel free to use your own links or adjust which variables are used to generate the post. Use post.export() to see which data can be retrieved.

Curriculum

• Part 0: How To Install Steem-python, The Official Steem Library For Python
• Part 1: How To Configure The Steempy CLI Wallet And Upvote An Article With Steem-Python
• Part 2: How To Stream And Filter The Blockchain Using Steem-Python
• Part 3: Creating A Dynamic Autovoter That Runs 24/7
• Part 4: How To Follow A Voting Trail Using Steem-Python
• Part 5: Post An Article Directly To The Steem Blockchain And Automatically Buy Upvotes From Upvote Bots
• Part 6: How To Automatically Reply To Mentions Using Steem-Python
• Part 7: How To Schedule Posts And Manually Upvote Posts For A Variable Voting Weight With Steem-Python
• Part 8: How To Create Your Own Upvote Bot Using Steem-Python
• Part 9: How To Calculate A Post's Total Rewards Using Steem-Python

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The code for this tutorial can be found on GitHub!

This tutorial was written by @juliank in conjunction with @amosbastian.

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Posted on Utopian.io - Rewarding Open Source Contributors

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