Read, Write and Parse JSON using Python

JSON is a lightweight data format for data interchange which can be easily read and written by humans, easily parsed and generated by machines. It is a complete language-independent text format. To work with JSON data, Python has a built-in package called json.

Example:
s = '{"id":01, "name": "Emily", "language": ["C++", "Python"]}'

The syntax of JSON is considered as a subset of the syntax of JavaScript including the following:

Name/Value pairs: Represents Data, name is followed by ‘:'(colon) and the Name/Value pairs separated by, (comma).
Curly braces: Holds objects.
Square brackets: Hold arrays with values separated by, (comma).

Keys/Name must be strings with double quotes and values must be data types amongst the following:

String
Number
Object (JSON object)
array
Boolean
Null

Example:
 {
   "employee": [

      {
         "id": "01",
         "name": "Amit",
         "department": "Sales"
      },

      {
         "id": "04",
         "name": "sunil",
         "depatment": "HR"
      }
   ]
}

Parse JSON (Convert from JSON to Python)

json.loads() method can parse a json string and the result will be a Python dictionary.

Syntax:

json.loads(json_string)

Example:

# Python program to convert JSON to Python 
  
  
import json 
  
# JSON string 
employee ='{"id":"09", "name": "Nitin", "department":"Finance"}'
  
# Convert string to Python dict 
employee_dict = json.loads(employee) 
print(employee_dict) 
  
print(employee_dict['name']) 

Output:

{'id': '09', 'department': 'Finance', 'name': 'Nitin'}
Nitin

Python read JSON file

json.load() method can read a file which contains a JSON object. Consider a file named employee.json which contains a JSON object.

Syntax:

json.load(file_object)

Example: Let’s suppose the JSON looks like this.

pyhton-append-json1

We want to read the content of this file. Below is the implementation.

# Python program to read 
# json file 
   
   
import json 
   
# Opening JSON file 
f = open('data.json',) 
   
# returns JSON object as  
# a dictionary 
data = json.load(f) 
   
# Iterating through the json 
# list 
for i in data['emp_details']: 
    print(i) 
   
# Closing file 
f.close() 

Output:

python-read-json-output1

Here, we have used the open() function to read the JSON file. Then, the file is parsed using json.load() method which gives us a dictionary named data.

Convert from Python to JSON

json.dumps() method can convert a Python object into a JSON string.

Syntax:

json.dumps(dict, indent)

It takes two parameters:

dictionary – name of dictionary which should be converted to JSON object.
indent – defines the number of units for indentation

Example:

# Python program to convert 
# Python to JSON 
   
   
import json 
   
# Data to be written 
dictionary ={ 
  "id": "04", 
  "name": "sunil", 
  "depatment": "HR"
} 
   
# Serializing json  
json_object = json.dumps(dictionary, indent = 4) 
print(json_object) 

Output:

{
    "depatment": "HR",
    "id": "04",
    "name": "sunil"
}

The following types of Python objects can be converted into JSON strings:

dict
list
tuple
string
int
float
True
False
None

Python objects and their equivalent conversion to JSON:

Python	JSON Equivalent
dict	object
list, tuple	array
str	string
int, float	number
True	true
False	false
None	null

Writing JSON to a file

json.dump() method can be used for writing to JSON file.

Syntax:

json.dump(dict, file_pointer)

It takes 2 parameters:

dictionary – name of dictionary which should be converted to JSON object.
file pointer – pointer of the file opened in write or append mode.

# Python program to write JSON 
# to a file 
   
   
import json 
   
# Data to be written 
dictionary ={ 
    "name" : "sathiyajith", 
    "rollno" : 56, 
    "cgpa" : 8.6, 
    "phonenumber" : "9976770500"
} 
   
with open("sample.json", "w") as outfile: 
    json.dump(dictionary, outfile) 

Output:

python-json-write-to-file

The above program opens a file named sample.json in writing mode using ‘w’. The file will be created if it does not exist. Json.dump() will transform dictionary to a JSON string and it will be saved in the file sample.json.

My Personal Notes

Parse JSON (Convert from JSON to Python)

Python read JSON file

Convert from Python to JSON

Writing JSON to a file

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