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.
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.dataContains 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 stringrequest.form: the key/value pairs in the body, from a HTML post form, or JavaScript request that isn't JSON encodedrequest.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 overlaprequest.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 existsrequest.form.get('name'): use get if the key might not existrequest.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.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
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()
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:
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"
}
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.
To post JSON with jQuery in JavaScript, use JSON.stringify to dump the data, and set the content type to application/json.
var value_data = [1, 2, 3, 4];
$.ajax({
type: 'POST',
url: '/process',
data: JSON.stringify(value_data),
contentType: 'application/json',
success: function (response_data) {
alert("success");
}
});
Parse it in Flask with request.get_json().
data = request.get_json()
Here's an example of posting form data to add a user to a database. Check request.method == "POST" to check if the form was submitted. Use keys from request.form to get the form data. Render an HTML template with a <form> otherwise. The fields in the form should have name attributes that match the keys in request.form.
from flask import Flask, request, render_template
app = Flask(__name__)
@app.route("/user/add", methods=["GET", "POST"])
def add_user():
if request.method == "POST":
user = User(
username=request.form["username"],
email=request.form["email"],
)
db.session.add(user)
db.session.commit()
return redirect(url_for("index"))
return render_template("add_user.html")
<form method="post">
<label for="username">Username</label>
<input type="text" name="username" id="username">
<label for="email">Email</label>
<input type="email" name="email" id="email">
<input type="submit">
</form>
If the body is recognized as form data, it will be in request.form. If it's JSON, it will be in request.get_json(). Otherwise the raw data will be in request.data. If you're not sure how data will be submitted, you can use an or chain to get the first one with data.
def get_request_data():
return (
request.args
or request.form
or request.get_json(force=True, silent=True)
or request.data
)
request.args contains args parsed from the query string, regardless of what was in the body, so you would remove that from get_request_data() if both it and a body should data at the same time.
When writing a Slack bot, which is supposed to send JSON data, I got a payload where the Content-Type was application/x-www-form-urlencoded.
I tried request.get_json() and it didn't work.
@app.route('/process_data', methods=['POST'])
def process_data():
req_data = request.get_json(force=True)
Instead I used request.form to get the form data field that contained JSON, then loaded that.
from flask import json
@ app.route('/slack/request_handler', methods=['POST'])
def request_handler():
req_data = json.loads(request.form["payload"])
If the content type is recognized as form data, request.data will parse that into request.form and return an empty string.
To get the raw data regardless of content type, call request.get_data(). request.data calls get_data(parse_form_data=True), while the default is False if you call it directly.
When posting form data with an HTML form, be sure the input tags have name attributes, otherwise they won't be present in request.form.
@app.route('/', methods=['GET', 'POST'])
def index():
print(request.form)
return """
<form method="post">
<input type="text">
<input type="text" id="txt2">
<input type="text" name="txt3" id="txt3">
<input type="submit">
</form>
"""
ImmutableMultiDict([('txt3', 'text 3')])
Only the txt3 input had a name, so it's the only key present in request.form.
@app.route('/addData', methods=['POST'])
def add_data():
data_in = mongo.db.Data
id = request.values.get("id")
name = request.values.get("name")
newuser = {'id' : id, 'name' : name}
if voter.find({'id' : id, 'name' : name}).count() > 0:
return "Data Exists"
else:
data_in.insert(newuser)
return "Data Added"
Import request:
from flask import request
URL query parameters:
name = request.args.get("name")
age = request.args.get("age")
Form Input:
name = request.form.get('name')
age = request.form.get('age')
OR (use indexing if you know the key exists, specify the name of input fields)
name = request.form['name']
age = request.form['age']
JSON Data (for content type application/json)
data = request.get_json()
