Display Dropdown Options in FastAPI without Using Enum Type

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What will you learn?

In this tutorial, you will learn how to create a dropdown list of options in a FastAPI application without relying on the enum data type. By leveraging Pydantic models and FastAPI’s features, we will dynamically generate dropdown choices based on runtime data.

Introduction to the Problem and Solution

When developing with FastAPI, the need to create dropdown options for APIs is common. While enums are traditionally used for this purpose, there are scenarios where more flexibility or dynamic behavior is desired. This guide presents an alternative approach to implement dropdown functionality without depending on enums.

To address this challenge, we will use Pydantic models along with FastAPI’s dependency injection feature. By generating the dropdown choices dynamically at runtime, we can create a solution that offers flexibility without the constraints of static enum definitions.

Code

from fastapi import FastAPI, Depends
from pydantic import BaseModel
from typing import List

app = FastAPI()

# Mock data representing dropdown options (can be fetched from database/API)
dropdown_options = ["Option 1", "Option 2", "Option 3"]

class DropdownRequest(BaseModel):
    selected_option: str

def get_dropdown_options():
    return dropdown_options

@app.get("/dropdown")
async def display_dropdown(options: List[str] = Depends(get_dropdown_options)):
    return {"Available Options": options}

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Explanation

  • Import necessary modules and set up the FastAPI instance.
  • Define mock data representing dropdown options (which could be retrieved from external sources).
  • Create a Pydantic model DropdownRequest to handle selected option requests.
  • Implement get_dropdown_options function to dynamically provide available choices.
  • Define a GET endpoint /dropdown that displays the dropdown options based on dynamic data.

This method allows for generating the dropdown list dynamically rather than using predefined enum values.

    How do I add new items dynamically to the dropdown list?

    You can update the dropdown_options list within your application logic to include new items as required.

    Can I fetch the dropdown options from an external API?

    Yes, you can modify get_dropdown_options() to make API calls and retrieve options dynamically.

    Is it possible to have nested or grouped options in the dropdown?

    By structuring your dropdown_options list appropriately (e.g., using dictionaries), you can achieve nested or grouped selections.

    How can I handle user selections from this dynamic dropdown in my backend logic?

    Process user selections made via this dynamic drop-down like any other form input submitted through your FastAPI endpoints.

    Can I integrate this with frontend frameworks like React or Vue.js?

    Absolutely! Design frontend components based on these dynamic choices fetched from your FastAPI backend endpoint.

    Conclusion

    In conclusion, by utilizing Pydantic models and FastAPI’s capabilities, we have successfully implemented a method for displaying dynamic drop-down lists in our applications without being limited by static enum types. This approach provides versatility while simplifying management of selectable options within APIs. Explore further customization possibilities based on project requirements!

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