Sorting Data with Query String Arguments and Enum

Allowing users to sort data based on different criteria is a common requirement in web applications. In FastAPI, you can use query string arguments and Enums to provide flexible sorting options. This guide will demonstrate how to implement sorting in your FastAPI endpoints.

Defining an Enum for Sorting Options

Create an Enum to represent the available sorting options:

Python

from enum import Enum

class SortOrder(Enum):
    asc = "asc"
    desc = "desc"

Adding a Query String Argument

Modify your endpoint to accept a sort_by query string argument:

Python

@app.get("/items")
async def get_items(sort_by: Optional[SortOrder] = Query(None)):
    # ...

Using the Query String Argument

Within your endpoint, use the sort_by argument to construct the appropriate SQLAlchemy query:

Python

if sort_by == SortOrder.asc:
    items = await db.query(Item).order_by(Item.name.asc()).all()
elif sort_by == SortOrder.desc:
    items = await db.query(Item).order_by(Item.name.desc()).all()
else:
    items = await db.query(Item).all()

Additional Factors

• Default Sorting: Specify a default sorting order if no sort_by argument is provided.
• Multiple Sorting Criteria: Allow users to sort by multiple fields by accepting a list of sorting options.
• Case Sensitivity: Consider using case-insensitive sorting if applicable.
• Validation: Validate the sort_by argument to ensure it’s a valid Enum value.

Example with Multiple Sorting Criteria

Python

@app.get("/items")
async def get_items(sort_by: Optional[List[SortOrder]] = Query(None)):
    query = db.query(Item)
    if sort_by:
        for field, order in sort_by:
            if field == "name":
                query = query.order_by(getattr(Item.name, order)())
            elif field == "price":
                query = query.order_by(getattr(Item.price, order)())
    items = await query.all()

By using query string arguments and Enums, you can provide users with a flexible and intuitive way to sort data in your FastAPI applications. This enhances the user experience and makes your API more user-friendly.