File Uploads

Learn essential concepts of file uploads in FastAPI.

What You'll Learn

This section covers file uploads, including:

• Handling single and multiple files

• Using UploadFile for file handling

• File validation and processing

• Storing uploaded files

• Error handling for uploads

• Production best practices

Core Concepts

File uploads require special handling:

• **UploadFile**: Async file handling in FastAPI

• **File**: Alternative type with less overhead

• **Streaming**: Handle large files efficiently

• **Validation**: Check file types and sizes

• **Storage**: Save files securely

Single File Upload Example

from fastapi import FastAPI, UploadFile, File

app = FastAPI()

@app.post("/uploadfile/")
async def upload_file(file: UploadFile = File(...)):
    contents = await file.read()
    filename = file.filename
    content_type = file.content_type
    return {
        "filename": filename,
        "size": len(contents),
        "content_type": content_type
    }

Multiple Files Upload Example

@app.post("/uploadfiles/")
async def upload_files(files: list[UploadFile] = File(...)):
    results = []
    for file in files:
        contents = await file.read()
        results.append({
            "filename": file.filename,
            "size": len(contents)
        })
    return results

Real-World Usage

File uploads are essential for:

• **Image uploads**: Profile pictures, gallery images

• **Document uploads**: PDFs, CSV for import

• **Media processing**: Video uploads, audio files

• **Data import**: Excel sheets, JSON datasets

🔑 Key Takeaways

• ✅ Understand the purpose of file uploads

• ✅ Know when to apply this pattern

• ✅ Follow best practices consistently

• ✅ Test thoroughly in production scenarios

Next step: Explore the advanced section for production patterns and optimization techniques.