Get the data received in a Flask request

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Get the data received in a Flask request

I want to be able to get the data sent to my Flask app. I’ve tried accessing request.data but it is an empty string. How do you access request data?

from flask import request
@app.route('/', methods=['GET', 'POST'])
def parse_request():
    data = request.data  # data is empty
    # need posted data here

The answer to this question led me to ask Get raw POST body in Python Flask regardless of Content-Type header next, which is about getting the raw data rather than the parsed data.

Asked By: ddinchev

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Answer #1:

The docs describe the attributes available on the request. In most common cases request.data will be empty because it’s used as a fallback:

request.data Contains the incoming request data as string in case it came with a mimetype Flask does not handle.

  • request.args: the key/value pairs in the URL query string
  • request.form: the key/value pairs in the body, from a HTML post form, or JavaScript request that isn’t JSON encoded
  • request.files: the files in the body, which Flask keeps separate from form. HTML forms must use enctype=multipart/form-data or files will not be uploaded.
  • request.values: combined args and form, preferring args if keys overlap
  • request.json: parsed JSON data. The request must have the application/json content type, or use request.get_json(force=True) to ignore the content type.

All of these are MultiDict instances (except for json). You can access values using:

  • request.form['name']: use indexing if you know the key exists
  • request.form.get('name'): use get if the key might not exist
  • request.form.getlist('name'): use getlist if the key is sent multiple times and you want a list of values. get only returns the first value.
Answered By: Robert

Answer #2:

To get the raw data, use request.data. This only works if it couldn’t be parsed as form data, otherwise it will be empty and request.form will have the parsed data.

from flask import request
request.data
Answered By: clyfish

Answer #3:

For URL query parameters, use request.args.

search = request.args.get("search")
page = request.args.get("page")

For posted form input, use request.form.

email = request.form.get('email')
password = request.form.get('password')

For JSON posted with content type application/json, use request.get_json().

data = request.get_json()
Answered By: Fizer Khan

Answer #4:

Here’s an example of parsing posted JSON data and echoing it back.

from flask import Flask, request, jsonify
app = Flask(__name__)
@app.route('/foo', methods=['POST']) 
def foo():
    data = request.json
    return jsonify(data)

To post JSON with curl:

curl -i -H "Content-Type: application/json" -X POST -d '{"userId":"1", "username": "fizz bizz"}' http://localhost:5000/foo

Or to use Postman:

using postman to post JSON

Answered By: Little Roys

Answer #5:

If you post JSON with content type application/json, use request.get_json() to get it in Flask. If the content type is not correct, None is returned. If the data is not JSON, an error is raised.

@app.route("/something", methods=["POST"])
def do_something():
    data = request.get_json()
Answered By: Amit Karnik

Answer #6:

To get the raw post body regardless of the content type, use request.get_data(). If you use request.data, it calls request.get_data(parse_form_data=True), which will populate the request.form MultiDict and leave data empty.

Answered By: Xiao

Answer #7:

To get request.form as a normal dictionary , use request.form.to_dict(flat=False).

To return JSON data for an API, pass it to jsonify.

This example returns form data as JSON data.

@app.route('/form_to_json', methods=['POST'])
def form_to_json():
    data = request.form.to_dict(flat=False)
    return jsonify(data)

Here’s an example of POST form data with curl, returning as JSON:

$ curl http://127.0.0.1:5000/data -d "name=ivanleoncz&role=Software Developer"
{
  "name": "ivanleoncz",
  "role": "Software Developer"
}
Answered By: ivanleoncz

Answer #8:

Use request.get_json() to get posted JSON data.

data = request.get_json()
name = data.get('name', '')

Use request.form to get data when submitting a form with the POST method.

name = request.form.get('name', '')

Use request.args to get data passed in the query string of the URL, like when submitting a form with the GET method.

request.args.get("name", "")

request.form etc. are dict-like, use the get method to get a value with a default if it wasn’t passed.

Answered By: Ravin Gupta

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