Python | Check whether a string is valid json or not
Given a Python String, the task is to check whether the String is a valid JSON object or not. Let’s try to understand the problem using different examples in Python.
Validate JSON String in Python
There are various methods to Validate JSON schema in Python here we explain some generally used methods for validating JSON schema in Python which are the following:
- Check Whether a String Is Valid JSON
- Use JSON Schema to Validate JSON Strings
- Checking Validity for Multi-Line JSON String
Check Whether a String Is Valid JSON
In the below example, the string is an invalid JSON because, the string characters are enclosed in single quotes (‘), but as per valid JSON schema, strings must be enclosed in double quotes (“).
Python3
# Python code to demonstrate # checking whether string # is valid json or not import json ini_string = "{'akshat' : 1, 'nikhil' : 2}" # printing initial ini_string print ( "initial string" , ini_string) # checking for string try : json_object = json.loads(ini_string) print ( "Is valid json? true" ) except ValueError as e: print ( "Is valid json? false" ) |
Output:
initial string {'akshat' : 1, 'nikhil' : 2}
Is valid json? false
Use JSON Schema to Validate JSON Strings
In this example the below code uses a function, `is_valid`, to check JSON string validity with `json.loads()`. It tests the function on three JSON strings containing various data types and prints whether each string is valid or not.
Python3
import json # function to check for JSON String validity def is_valid(json_string): print ( "JSON String:" , json_string) try : json.loads(json_string) print ( " Is valid?: True" ) except ValueError: print ( " Is valid?: False" ) return None # checking for string and integers is_valid( '{"name":"John", "age":31, "Salary":2500000}' ) # checking for integer and float is_valid( '{ "Subjects": {"Maths":85.01, "Physics":90}}' ) # checking for boolean type values is_valid( '{"success": true}' ) |
Output:
JSON String: {"name":"John", "age":31, "Salary":2500000}
Is valid?: True
JSON String: { "Subjects": {"Maths":85.01, "Physics":90}}
Is valid?: True
JSON String: {"success": true}
Is valid?: True
Checking Validity for Multi-Line JSON String
Here we have taken a sample, multi-line Python string, and we’ll try to check the validity of the String for a valid JSON string or not. Although this String contains multiple line-breaks, still json.JSONDecoder able to parse this String.
Python3
import json # function to check for JSON String validity def is_valid(json_string): print ( "JSON String:" , json_string) try : json.loads(json_string) print ( " Is valid?: True" ) except ValueError: print ( " Is valid?: False" ) return None # parsing multi-line JSON string json_str = """ { "Person": [ {"name": "P_1", "age": 42}, {"name": "P_2", "age": 21}, {"name": "P_3", "age": 36} ], "location": "1.1.0", "Country": "IND" } """ # call function for validation check # of the Python String is_valid(json_str) |
Output:
JSON String:
{
"Person": [
{"name": "P_1", "age": 42},
{"name": "P_2", "age": 21},
{"name": "P_3", "age": 36}
],
"location": "1.1.0",
"Country": "IND"
}
Is valid?: True
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