How to use the json module to convert JSON strings into Python objects in Python 3.x

How to use the json module in Python 3.x to convert JSON strings into Python objects

JSON (JavaScript Object Notation) is a lightweight data exchange format commonly used for front-end and back-end data transmission and storage. In Python, you can use the json module to process JSON data. The json module provides a simple set of functions and methods for converting JSON strings into Python objects. This article will introduce how to use the json module to parse and convert JSON strings.

First, we need to import the json module.

import json

Next, we need a JSON string, which can be represented by single quotes or double quotes. Here is a sample JSON string:

json_str = '{"name": "John", "age": 30, "city": "New York"}'

With the JSON string, we can use the loads function in the json module to parse it into a Python object. The loads function parses the JSON string into a dictionary object.

data = json.loads(json_str)

Now, the data object is a Python dictionary, and we can access its values ​​through keys.

print(data['name'])  # 输出: John
print(data['age'])   # 输出: 30
print(data['city'])  # 输出: New York

In addition to dictionary objects, JSON strings can also be parsed into other Python data types, such as lists. Here is a sample JSON string:

json_str = '["apple", "banana", "orange"]'

We can use the loads function to parse it into a Python list.

data = json.loads(json_str)

Now, the data object is a Python list, and we can use subscripts to access its elements.

print(data[0])  # 输出: apple
print(data[1])  # 输出: banana
print(data[2])  # 输出: orange

At the same time, the json module also provides the dumps function, which can convert Python objects into JSON strings. Here is an example:

data = {
    'name': 'John',
    'age': 30,
    'city': 'New York'
}

json_str = json.dumps(data)
print(json_str)  # 输出: {"name": "John", "age": 30, "city": "New York"}

In addition to dictionaries and lists, the json module can also handle other data types, such as strings, integers, floating point numbers, and Boolean values.

json_str = 'true'
data = json.loads(json_str)
print(data)  # 输出: True

json_str = '42'
data = json.loads(json_str)
print(data)  # 输出: 42

json_str = '3.14'
data = json.loads(json_str)
print(data)  # 输出: 3.14

json_str = '"Hello, World!"'
data = json.loads(json_str)
print(data)  # 输出: Hello, World!

It should be noted that the JSON string must conform to the JSON format specification, otherwise an error will occur in parsing. For example, key names and string values ​​in JSON strings must use double quotes, and single quotes cannot be used.

When processing JSON data, we can also use some parameters to perform customized operations. These parameters include: indent, sort_keys, ensure_ascii, etc. For specific usage, please refer to the documentation of the json module.

To summarize, using the json module can easily convert JSON strings into Python objects for operation and processing. In Python 3.x, the loads function provided by the json module can parse JSON strings into Python objects, and the dumps function can convert Python objects into JSON strings. This allows us to easily process JSON data in Python.

I hope that through the introduction of this article, readers will have an understanding of how to use the json module to convert JSON strings, so that they can better process and utilize JSON data in actual development.

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