Python: How do I make changes and add onto in json

Question

{
    "blogs": [
         {
          "header": "Welcome",
         "author": "Auriga",
         "team"  : "Webmaster",
         "date"  : ["2015", "12", "12"],
         "paragraphs" : [
          "Blah blah blah"
       ],
        "images": []
    }
],

Basically I want to add this another blog entry and insert my own variables and add onto what I already have.

       {
         "header": "",
         "author": "",
         "team"  : "",
         "date"  : ["", "", ""],
         "paragraphs" : [
          ""
       ],
        "images": []
    },

Using that template up there how do I insert variables and add into my json file.

I'm trying to make the end result look like this

{
  "blogs": [
     {
      "header": "Welcome",
      "author": "Auriga",
      "team"  : "Webmaster",
      "date"  : ["2015", "12", "12"],
      "paragraphs" : [
      "Blah blah blah"
    ],
     "images": []
  },
  {
      "header": "BLah blah",
      "author": "Blah blah",
      "team"  : "Blah Blah Blah",
      "date"  : ["2015", "12", "12"],
      "paragraphs" : [
      "Blah blah blah"
    ],
     "images": []
  },      


],

I tried using link and I have been just stuck searching online how to do something like this.

Be more specific about your problem. What exactly does not work? — timgeb, Dec 13 '15 at 01:22
You don't seem to understand. Let me be more clear: WHAT are you doing and WHAT is the error? — timgeb, Dec 13 '15 at 01:30
I am trying to make a python script that adds more blog entry's and im stuck on figuring out how to put it inside the 'blog' section. I have no errors btw. — maxadorable, Dec 13 '15 at 01:32

score 2 · Accepted Answer · answered Dec 13 '15 at 02:04

Since there are a lot of things you might be interested I wrote a small code to demonstrate the basics you should take care about at the beginning:

Reading files
Python dictionaries (how they work, how to access keys and values, how to update them, ...)
Python lists (how they work, how to access elements, ...)
Python's json module (loading and dumping data, conversion from JSON to Python's datatypes, ...)

Assuming you have a JSON-file called blog_entries.json with the following contents:

[{
    "header": "First Story",
    "author": "Tim",
    "team": "department one",
    "date": ["2015", "12", "12"],
    "paragraphs": ["First para", "Second para"],
    "images": []
}, {
    "header": "Second Story",
    "author": "Steven",
    "team": "department two",
    "date": ["2015", "12", "12"],
    "paragraphs": ["First para", "Second para"],
    "images": []
}, {
    "header": "Third Story",
    "author": "Bob",
    "team": "department three",
    "date": ["2015", "12", "12"],
    "paragraphs": ["First para", "Second para"],
    "images": []
}, {
    "header": "Fourth Story",
    "author": "John",
    "team": "department four",
    "date": ["2015", "12", "12"],
    "paragraphs": ["First para", "Second para"],
    "images": []
}]

We can load this file and do some data manipulation. Please see comments in code for further details:

#!/usr/bin/env python3
# coding: utf-8


# use json module to handle json-formatted data in python
import json


new_entry = {"header": "The story to be added",
    "author": "me",
    "team": "editor",
    "date": ["2015", "12", "13"],
    "paragraphs": ["First para", "Second para"],
    "images": []
    }


update_entry = {"header": "Formerly written by John",
    "author": "me"
    }


# Use `with open()` in order to open a file and close it automatically after all operations are done.
with open('blog_entries.json') as f:
    existing_entries = json.load(f)

# Before starting any manipulation print the existing blog entries in order to double-check.
# Use `json.dumps()` in order to get a nicely formatted output
print(json.dumps(existing_entries, sort_keys=True, indent=4))


# Since `json.load()` converts the json data to the appropiate Python datatype (list or dict) we can use Python's
# standard operations for those datatypes.
# `exiting_blogs` will be a list since it's an array in the json-formatted file (an object would become a dict),
# so we append the new blog entry and print it again in order to double-check
existing_entries.append(new_entry)
print(json.dumps(existing_entries, sort_keys=True, indent=4))


# OK, let's say we want to manipulate the blog entry which was written by John.
# First, we have to find the desired data in the list.
for entry in existing_entries:
    if entry['author'] == 'John':
        # Update the existing entry (of datatype dict) with the new elements which will overwrite the old ones.
        entry.update(update_entry)
    else:
        # We did not find any entry written by John. Think about this error case later...
        pass


# This output will show that the entry written by John was updated with the data given in `update_enry`.
print(json.dumps(existing_entries, sort_keys=True, indent=4))


# Write the manipulated data to a new file.
# For sure, we could use the same file as we read from, but this would make comparing the file contents somehow
# difficult
with open('new_blog_entries.json', 'w') as f:
    json.dump(existing_entries, f)

score 1 · Answer 2 · answered Dec 13 '15 at 02:03

Use append:

import json
data = {
    "blogs": [
         {
          "header": "Welcome",
         "author": "Auriga",
         "team"  : "Webmaster",
         "date"  : ["2015", "12", "12"],
         "paragraphs" : [
            "Blah blah blah"
        ],
        "images": []
        }
    ],
}

print(json.dumps(data.get('blogs'), indent=2))

more_data = {
         "header": "",
         "author": "",
         "team"  : "",
         "date"  : ["", "", ""],
         "paragraphs" : [
          ""
       ],
        "images": []
    }

data['blogs'].append(more_data)

print(json.dumps(data, indent=2))

Python: How do I make changes and add onto in json

2 Answers2