How to capture arbitrary paths at one route in FastAPI

FastAPI is a modern Python framework for building scalable APIs. It is fast, easy to use, and allows the creation of robust APIs. In this article, we will see how to capture arbitrary paths at one route in FastAPI.

Capture Arbitrary Path in FastAPI

In FastAPI, arbitrary paths can be captured using the Path parameters. Path parameters allow you to define a part of the URL as a parameter, which can be used to parse the path and do the necessary operations on it.

Syntax:

Below is the basic syntax for capturing arbitrary paths.

Syntax: @app.get(“/item/{arbitrary_path:path}”)async def read_item(arbitrary_path: str): return {“path”: arbitrary_path}

Here, the path modifier allows it to capture arbitrary paths.

Example 1: Capture and Return the Path

Below is the basic example of capturing the path and returning it. Here, we define a route that captures an arbitrary path after /item/ using the path parameter {arbitrary_path:path}. The :path will accept the arbitrary path.

main.py

Python3

from fastapi import FastAPI

app = FastAPI()


@app.get("/item/{arbitrary_path:path}")
async def read_item(arbitrary_path: str):
    return {"path": arbitrary_path}

To test this, run this command in terminal.

$ uvicorn main:app --reload

Now head over to:

http://127.0.0.1:8000/docs

You should see something like this

openai doc

Output

Example 2: Parse the Path and Apply Operations

Below is the example to parse the path and apply any operations accordingly. In this example, we are parsing the path and printing the id. Any additional logic can be added here.

main.py

Python3

from fastapi import FastAPI

app = FastAPI()


@app.get("/item/{arbitrary_path:path}")
async def read_item(arbitrary_path: str):
    path_parts = arbitrary_path.split("/")

    if len(path_parts) == 2:

        entity = path_parts[0]
        id = path_parts[1]

        if entity == "user":
            return f"user path with id {id}"
        elif entity == "product":
            return f"product path with id {id}"

    else:
        return "new path"

To test this, run this command in terminal.

$ uvicorn main:app --reload

Now head over to

http://127.0.0.1:8000/docs

Output