How to Get the Data Received in a Flask Request

Python Flask Werkzeug

When working with a Python Flask application, it is common to receive data in a request. However, accessing this data can sometimes be tricky. In this article, we will explore various methods to get the data received in a Flask request.

Using the request object

Flask provides a request object, which allows access to the data sent in a request. To access this data, you first need to import the request module from the Flask library:


from flask import request

Next, you can use the following methods to retrieve the data based on the type of request:

  • For GET requests:
    • 
@app.route('/', methods=['GET'])
def parse_request():
    data = request.args.get('key')
    # process the data

    In this example, request.args is a dictionary-like object that allows access to the query parameters sent in the URL. You can use the get() method to retrieve the value of a specific parameter based on its key.

  • For POST requests:
    • 
@app.route('/', methods=['POST'])
def parse_request():
    data = request.form.get('key')
    # process the data

    In this example, request.form is a dictionary-like object that allows access to the form data sent in the request body. You can use the get() method to retrieve the value of a specific field based on its key.

  • For file uploads:
    • 
@app.route('/', methods=['POST'])
def parse_request():
    file = request.files['file']
    # process the file

    In this example, request.files is a dictionary-like object that allows access to the files sent in the request. You can retrieve a specific file based on its key.

Accessing the raw request data

If you need to access the raw data of a request, regardless of its content type header, you can use the following code:


@app.route('/', methods=['POST'])
def parse_request():
    data = request.get_data(as_text=True)
    # process the data

In this example, the get_data() method is used to retrieve the raw data as a string. The as_text parameter is set to True to ensure the data is returned as a text string rather than bytes.

Handling JSON data

If the request data is in JSON format, you can use the following code to retrieve and parse it:


@app.route('/', methods=['POST'])
def parse_request():
    data = request.get_json()
    # process the data

In this example, the get_json() method is used to retrieve and parse the JSON data sent in the request. The resulting data is returned as a dictionary.

Handling multipart form data

If the request data contains multipart form data, such as when submitting a form with file uploads, you can use the following code to retrieve and process the data:


@app.route('/', methods=['POST'])
def parse_request():
    data = request.form.getlist('key')
    # process the data

In this example, the getlist() method is used instead of get() to retrieve all values associated with a specific field key. This is necessary when dealing with multiple file uploads or select multiple form fields.

Conclusion

In this article, we have explored various methods to get the data received in a Flask request. Whether it is query parameters, form data, file uploads, or JSON data, Flask provides convenient methods to retrieve and process the data. By using the request object, you can easily access the data and incorporate it into your Flask application.

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