Schema Validation with Pydantic in Python fastapi

Hey guys, in this post we will learn how to create the fields validation with API using Pydantic in Python fastapi.

1. Import pydantic
2. Create Class
3. Create function with method (Post|PUT etc)
4. Start webserver
5. Run API in Postman

Import pydantic:

from pydantic import BaseModel

Create Class:

class Post(BaseModel):
    title: str
    description: str

Create Function:

@app.post("/createpost")
def createPost(new_post : Post):
        print(new_post)
        return {"Data": new_post}

Start Web Server:

uvicorn main:app --reload

Run API in Postman:

http://127.0.0.1:8000/createpost

Example with complete code:

from fastapi import FastAPI
from fastapi.params import Body
from pydantic import BaseModel

app = FastAPI()

class Post(BaseModel):
    title: str
    description: str

@app.post("/createpost")
def createPost(new_post : Post):
        print(new_post)
        return {"Data": new_post}

you can see in above example that in class Post title and description is using as a field but in postman body fields are (post_title, post_description) so on submit the api it will trough the “field require” error.

🙂 Keep Learning