What is JSON?
JSON stands for Java-Script Object Notation. it is simply a data representation format just like XML and YAML. it is widely used across the internet for almost every API you access, configurations, games, text editors etc. it is lightweight because of its small file size and easy to read/write as there is not any opening and closing tag like XML. There are some data types which can be used in json.
String- "Hello world"
Numbers = 0, -3. 1000
Arrays = [0,1,2]
Objects = { "name": "Rick", "profession": "scientist"} or
null
Why should you learn this?
The ability to process JSON files becomes important for programmers, especially in fields where data is constantly being input and output. In the context of data loading and storing, JSON is the most commonly used format.
Today, We are learning this using Python.
Working with JSON using Python:
At first, working with json data, we will import the build-in module of Python called json. import is the keyword, used to import any package in Python.
import json
Here, a variable named people_str contains a list of dictionaries named people.
people_str = '''
"people"= [
{
"name": "John Doe",
"age": 25,
"city": "New York",
"salary": 50000
},
{
"name": "Jane Smith",
"age": 30,
"city": "Los Angeles", "salary": 60000
},
{
"name": "Mark Johnson",
"age": 35,
"city":"Chicago",
"salary": 55000
},
{
"name": "Sarah Wilson",
"age": 28,
"city": "San Francisco",
"salary": 65000
},
{
"name": "Michael Brown",
"age": 32,
"city": "Boston",
"salary": 70000
}
]
'''
Hint: You can use any data generator or AI tool such as CHAT-GPT to generate the sample data, in this case, JSON data.
JSON file must be created with an extension as .json.
Now, the First thing we could do is save this data into the JSON file. to do that, we first need to convert this dictionary into JSON objects. json module provides a method called dumps(), to convert Python dictionaries into json objects.
Let's learn more about it.
dumps():
We have a built-in function in the json module called dumps(). What it does is, converts the dictionary into JSON objects.
##dumps takes an actual data object and turn it into string
json_str = json.dumps(people_str,indent=2)
with open('data.json', 'w') as file:
file.write(json_str)
Here, We defined a variable named json_str which contains the dictionary format data as a string.
the dumps() function takes the first argument people_str and the second is the indent keyword. indent provides some indentation as per the value to make the json data more readable. if we do not do this, it will show the data in a single line in json file.
with open('data.json', 'w') as file:
file.write(json_str)
Here, We are opening a file named data.json in writing mode and then writing the data into it. above code will create a file named 'data.json', if it doesn't exist already and write the above data into this. (if it exists, it will override that file)
loads():
loads() is the function provided by json module in Python that is used to convert json objects into the dictionary(python's equivalent object).
import json
with open('data.json','r') as file:
json_obj = json.loads(file.read())
The second line in the above code is opening the existing file named data.json(in which we have saved the data) in reading mode and loading file data into json_obj
print(json_obj)
This line will print all the data in data.json, as the dictionary.
Output:
"people"= [
{
"name": "John Doe",
"age": 25,
"city": "New York",
"salary": 50000
},
{
"name": "Jane Smith",
"age": 30,
"city": "Los Angeles", "salary": 60000
},
{
"name": "Mark Johnson",
"age": 35,
"city":"Chicago",
"salary": 55000
},
{
"name": "Sarah Wilson",
"age": 28,
"city": "San Francisco",
"salary": 65000
},
{
"name": "Michael Brown",
"age": 32,
"city": "Boston",
"salary": 70000
}
]
We can try printing other things as well.
print(json_obj['people'])
print(json_obj['people'][0]['name'])
This is going to print the list and first name respectively.
Now, Let's take an object-oriented example to understand this more.
import json
class person:
def __init__(self,name, age, city, salary):
self.name = name
self.age = age
self.city = city
self.salary = salary
After importing the json module, We created a class named person which has a constructor. in short, A constructor is used to initialize data members. This constructor is having data members as name, age, city and salary.
def display(self):
print(self.name, self.age, self.city, self.salary)
This is the display() function which will display the values of the name, age, city and salary.
Exporting data into json file:
Now let's export this data into a json file.
def export_to_json(self, filename):
person_dict = {'name':self.name, 'age':self.age,'city':self.city,'salary':self.salary}
Here, we created a function named export_to_json() and passed the filename as an argument. our next move is to define a variable named person_dict which contains nothing but the data which we are exporting.
with open(filename, 'w') as f:
f.write(json.dumps(person_dict, indent = 2))
If you are reading this blog, you must be aware of the next line, We are opening a file in writing mode, here. It will create a file named filename and Write the data into it, with an indentation of 2. Indentation is optional, but it is a good practice to keep the data more readable.
def load_from_json(self,filename):
with open(filename, 'r') as f:
data = json.loads(f.read())
self.name= data['name']
self.age= data['age']
self.city = data['city']
self.salary = data['salary']
As we did before, here we are exporting json data into a Python dictionary.
p1 = person("Rick", 70, "Seattle", 200)
p1.display()
p1.export_to_json("demo.json")
We created an object named p1 of class person and called the functions. when we run the above code. it will create a file, named demo.json if it doesn't exist already . and write the data into it.
Output Window:
Rick 70 Seattle 200
json file:
## demo.json
{
"name": "Rick",
"age": 70,
"city": "Seattle",
"salary": 200
}
Thank you for taking the time to read this blog post. I sincerely hope that the information provided here proves to be helpful to you.