Check the size of an uploaded file in FastAPI

To check the size of an uploaded file in FastAPI and ensure it does not exceed 500MB, you can use the UploadFile class and inspect its content_length property. Below is an example code that checks the file size and raises an exception if it exceeds the specified limit.

from fastapi import FastAPI, UploadFile, HTTPException

app = FastAPI()

@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile = File(...)):
    # Maximum allowed file size (500MB)
    max_file_size = 500 * 1024 * 1024  # 500MB

    # Check the file size
    if file.content_length > max_file_size:
        raise HTTPException(status_code=413, detail="File size exceeds the limit of 500MB")

    # Additional logic to handle or store the file can be added here.
    # For example, use file.filename to get the file name and file.file to process the file content.

    return {"filename": file.filename}

 

In this code, file.content_length represents the size of the uploaded file. If this value is greater than max_file_size, an HTTPException is raised, and the client receives a response with the message "File size exceeds the limit of 500MB."

By limiting the file size in this way, the server can respond appropriately when a client attempts to upload a file that exceeds the defined limit.