Formulardaten und Datei-Uploads
Verarbeiten Sie herkömmliche HTML-Formulardaten und implementieren Sie Datei-Uploads mit den integrierten Funktionen von FastAPI.
Formulardaten und Datei-Uploads ist eine kostenlose FastAPI Backend Development Bootcamp-Lektion auf CoddyKit. Dies ist Lektion 3 von 4. Du kannst die komplette Lektion unten kostenlos lesen – dann übst du sie direkt im Browser mit einem integrierten Code-Editor und einem KI-Tutor rund um die Uhr. Sie ist Teil des FastAPI Backend Development Bootcamp-Lernpfads, und dein Fortschritt wird über Web und CoddyKit-App synchronisiert. Der FastAPI Backend Development Bootcamp-Kurs umfasst insgesamt 4 Lektionen.
Teile dieser Lektion wurden noch nicht übersetzt und werden auf Englisch angezeigt.
Form Data Basics
When you fill out a web form (like a login or registration page) and click "submit," the data you entered is often sent as form data.
This is a traditional way for browsers to send information to a server, different from sending JSON in a request body.
Form data can be sent in two main ways:
application/x-www-form-urlencoded: For simple key-value pairs.multipart/form-data: Used when files are involved, or for larger, more complex data.
FastAPI's Form Dependency
FastAPI makes handling form data easy using the Form dependency from fastapi.
It works similarly to Query or Path parameters, but it tells FastAPI to expect the data in the request body as form fields.
You import it like this: from fastapi import FastAPI, Form.
Basic Form Endpoint Example
Let's create an endpoint that accepts a username and password as form data. Notice how username and password are explicitly marked with Form(...).
This tells FastAPI to parse them from the form body, not as JSON or query parameters.
from fastapi import FastAPI, Form
import uvicorn
app = FastAPI()
@app.post("/login/")
async def login(username: str = Form(...), password: str = Form(...)):
return {"username": username, "message": "Login successful!"}
if __name__ == "__main__":
uvicorn.run(app, host="0.0.0.0", port=8000)Interacting with Form Data
You can test this endpoint using tools like curl or by creating a simple HTML form. The -d flag in curl sends form data.
Make sure your FastAPI application from the previous scene is running!
curl -X POST "http://127.0.0.1:8000/login/" \
-H "Content-Type: application/x-www-form-urlencoded" \
-d "username=coddy&password=secret"File Uploads Explained
Uploading files (like images, documents, or videos) is a common web task. This type of data is sent using multipart/form-data encoding.
FastAPI provides special tools to handle these uploads efficiently, allowing you to access file contents and metadata.
FastAPI's UploadFile
For file uploads, FastAPI uses the UploadFile class (from fastapi) along with the File dependency.
When you declare a parameter with File(...) and type-hint it as UploadFile, FastAPI handles the file stream.
filename: The name of the uploaded file.content_type: The file's MIME type (e.g.,image/jpeg).file: A SpooledTemporaryFile object, allowing you to read its contents.
from fastapi import FastAPI, File, UploadFile
import uvicorn
app = FastAPI()
@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile = File(...)):
return {"filename": file.filename, "content_type": file.content_type}
if __name__ == "__main__":
uvicorn.run(app, host="0.0.0.0", port=8000)Saving One Uploaded File
After receiving an UploadFile, you can read its content and save it to a local disk or cloud storage. Here's how to save it locally.
Remember to handle potential errors during file operations.
from fastapi import FastAPI, File, UploadFile
import uvicorn
import shutil
import os
app = FastAPI()
# Ensure the 'files' directory exists
os.makedirs("files", exist_ok=True)
@app.post("/uploadandsave/")
async def upload_and_save_file(file: UploadFile = File(...)):
file_location = f"files/{file.filename}"
with open(file_location, "wb+") as file_object:
shutil.copyfileobj(file.file, file_object)
return {"message": f"File '{file.filename}' saved at '{file_location}'"}
if __name__ == "__main__":
uvicorn.run(app, host="0.0.0.0", port=8000)Uploading Many Files
What if you need to upload several files at once? FastAPI supports this by allowing you to define a parameter as a list of UploadFile.
Each file in the list will be an UploadFile object, which you can then process individually.
from fastapi import FastAPI, File, UploadFile
from typing import List
import uvicorn
app = FastAPI()
@app.post("/uploadmultiple/")
async def create_upload_files(files: List[UploadFile] = File(...)):
uploaded_filenames = [file.filename for file in files]
return {"filenames": uploaded_filenames, "message": "Files received!"}
if __name__ == "__main__":
uvicorn.run(app, host="0.0.0.0", port=8000)Saving Multiple Uploads
Similar to single files, you can iterate through the list of UploadFile objects and save each one. This is useful for photo galleries or document uploads.
Always ensure proper error handling and secure file storage practices in a real application.
from fastapi import FastAPI, File, UploadFile
from typing import List
import uvicorn
import shutil
import os
app = FastAPI()
# Ensure the 'files' directory exists
os.makedirs("files", exist_ok=True)
@app.post("/uploadandsavemultiple/")
async def upload_and_save_multiple_files(files: List[UploadFile] = File(...)):
saved_files = []
for file in files:
file_location = f"files/{file.filename}"
with open(file_location, "wb+") as file_object:
shutil.copyfileobj(file.file, file_object)
saved_files.append(file.filename)
return {"message": f"Successfully uploaded: {', '.join(saved_files)}"}
if __name__ == "__main__":
uvicorn.run(app, host="0.0.0.0", port=8000)Form & File Check
You've learned about handling form data and file uploads. Let's test your understanding!
Lesson Summary
Great job! In this lesson, you mastered how to handle traditional form data and robust file uploads in FastAPI.
- We used
Form(...)for simple key-value form fields. - We explored
UploadFileandFile(...)for single and multiple file uploads. - You learned to save uploaded files to your server.
These techniques are crucial for building interactive web applications. Keep practicing!
Häufig gestellte Fragen
Ist die Lektion „Formulardaten und Datei-Uploads“ kostenlos?
Ja — der vollständige Text von „Formulardaten und Datei-Uploads“ ist hier im Web kostenlos zu lesen. Um sie interaktiv zu üben (integrierter Code-Editor und 24/7 KI-Tutor) und den Rest des FastAPI Backend Development Bootcamp-Kurses freizuschalten, upgrade auf CoddyKit PRO. Der FastAPI Backend Development Bootcamp-Kurs umfasst insgesamt 4 Lektionen.
Was lerne ich in „Formulardaten und Datei-Uploads“?
Verarbeiten Sie herkömmliche HTML-Formulardaten und implementieren Sie Datei-Uploads mit den integrierten Funktionen von FastAPI. Du übst FastAPI Backend Development Bootcamp mit praktischem Code, den du direkt im Browser ausführst, und ein 24/7 KI-Tutor beantwortet deine Fragen während du die Lektion bearbeitest.
Brauche ich Erfahrung, um FastAPI Backend Development Bootcamp zu starten?
Keine Vorkenntnisse erforderlich. FastAPI Backend Development Bootcamp auf CoddyKit ist für Anfänger bis fortgeschrittene Lernende strukturiert, sodass du hier starten oder von Anfang an beginnen und in deinem eigenen Tempo voranschreiten kannst. Dies ist Lektion 3 von 4.
Wie lange dauert die Lektion „Formulardaten und Datei-Uploads“?
Die meisten CoddyKit-Lektionen dauern etwa 5–10 Minuten. Jede ist kompakt und interaktiv, sodass du stetig Fortschritte machst und genau dort weitermachst, wo du aufgehört hast – im Web und in der App.
Kann ich in dieser FastAPI Backend Development Bootcamp-Lektion Code schreiben und ausführen?
Ja. Jede FastAPI Backend Development Bootcamp-Lektion enthält einen integrierten Code-Editor, sodass du echten Code direkt in deinem Browser schreibst und ausführst und sofort KI-Feedback erhältst — ohne lokale Einrichtung erforderlich.
Alle Lektionen in diesem Kurs
- Pydantic-Modelle für den Request-Body
- Response-Modelle und Statuscodes
- Formulardaten und Datei-Uploads
- Header, Cookies und benutzerdefinierte Antworten