Debug Your Infrastructure

Get Instant Solutions for Kubernetes, Databases, Docker and more

AWS CloudWatch
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.
Pod Stuck in CrashLoopBackOff
Database connection timeout
Docker Container won't Start
Kubernetes ingress not working
Redis connection refused
CI/CD pipeline failing

Fast API Invalid Query Parameter Type

The query parameter type does not match the expected type.

Understanding FastAPI

FastAPI is a modern, fast (high-performance), web framework for building APIs with Python 3.7+ based on standard Python type hints. It is designed to be easy to use and to provide high performance, on par with NodeJS and Go. FastAPI is particularly useful for building RESTful APIs quickly and efficiently.

Identifying the Symptom: Invalid Query Parameter Type

When working with FastAPI, you might encounter an error related to query parameters. A common symptom of this issue is receiving an error message indicating that the query parameter type does not match the expected type. This can lead to unexpected behavior or application crashes.

Example Error Message

When this issue occurs, you might see an error message similar to the following:

422 Unprocessable Entity: {'detail': [{'loc': ['query', 'param_name'], 'msg': 'value is not a valid integer', 'type': 'type_error.integer'}]}

Details About the Issue

The error arises when the type of a query parameter provided in a request does not match the type expected by the FastAPI application. FastAPI uses Python type hints to validate request data, and if the data does not conform to the expected type, it raises a validation error.

Common Causes

  • Providing a string where an integer is expected.
  • Using a float when an integer is required.
  • Incorrectly formatted data types.

Steps to Fix the Issue

To resolve the 'Invalid Query Parameter Type' error, follow these steps:

Step 1: Verify the Expected Type

Check the FastAPI endpoint definition to determine the expected type for the query parameter. For example:

from fastapi import FastAPI, Query

app = FastAPI()

@app.get("/items/")
async def read_items(q: int = Query(...)):
return {"q": q}

In this example, the query parameter q is expected to be an integer.

Step 2: Ensure Correct Parameter Type in Requests

When making requests to the FastAPI application, ensure that the query parameters match the expected types. For instance, if the parameter is expected to be an integer, do not provide a string or float.

import requests

response = requests.get("http://localhost:8000/items/?q=10")
print(response.json())

Step 3: Use Type Conversion if Necessary

If the input data is not in the correct type, consider converting it before sending the request. For example, convert a string to an integer if required.

Additional Resources

By following these steps, you can resolve the 'Invalid Query Parameter Type' error and ensure that your FastAPI application handles requests as expected.

Master 

Fast API Invalid Query Parameter Type

 debugging in Minutes

— Grab the Ultimate Cheatsheet

(Perfect for DevOps & SREs)

Most-used commands
Real-world configs/examples
Handy troubleshooting shortcuts
Your email is safe with us. No spam, ever.

Thankyou for your submission

We have sent the cheatsheet on your email!
Oops! Something went wrong while submitting the form.

Fast API Invalid Query Parameter Type

Cheatsheet

(Perfect for DevOps & SREs)

Most-used commands
Your email is safe thing.

Thankyou for your submission

We have sent the cheatsheet on your email!
Oops! Something went wrong while submitting the form.

MORE ISSUES

Deep Sea Tech Inc. — Made with ❤️ in Bangalore & San Francisco 🏢

Doctor Droid