How to Install Pydantic in Python

Pydantic is a popular Python library for data validation. It helps ensure your data matches expected formats. This guide will show you how to install it.

Prerequisites

Before installing Pydantic, ensure you have Python 3.7 or higher. Check your Python version using python --version.

python --version

If you don't have Python installed, download it from the official website first.

Install Pydantic Using pip

The easiest way to install Pydantic is via pip. Open your terminal or command prompt and run:

pip install pydantic

This will download and install the latest version of Pydantic.

Verify the Installation

After installation, verify it works. Create a Python file and import Pydantic:

 
import pydantic
print(pydantic.__version__)

Run the file. You should see the installed version number.

Basic Pydantic Example

Here's a simple example to test Pydantic. Create a model to validate data:

 
from pydantic import BaseModel

class User(BaseModel):
    name: str
    age: int

user = User(name="John", age=30)
print(user)

This creates a valid user object. Pydantic will raise an error if the data types don't match.

Common Installation Issues

If you get ModuleNotFoundError, check our guide on solving ModuleNotFoundError.

Other common issues include:

• Using an outdated Python version
• Not having pip installed
• Network connectivity problems

Upgrading Pydantic

To upgrade Pydantic to the latest version, use:

pip install --upgrade pydantic

This ensures you have all the latest features and bug fixes.

Using Pydantic in Projects

Pydantic works well with FastAPI and other frameworks. Here's how to use it in a project:

 
from pydantic import BaseModel, validator

class Product(BaseModel):
    name: str
    price: float
    
    @validator('price')
    def check_price(cls, v):
        if v <= 0:
            raise ValueError('Price must be positive')
        return v

This adds custom validation to ensure prices are positive.

Conclusion

Installing Pydantic is simple with pip. It provides powerful data validation for Python projects. Remember to check your Python version and pip installation if you encounter issues.

For more advanced features, check the official Pydantic documentation. Happy coding!