Get multiple request params of the same name

Question

My problem is that with the given code:

from flask import Flask, request

app = Flask(__name__)

@app.route("/")
def hello():
    return str(request.values.get("param", "None"))

app.run(debug=True)

and I visit:

http://localhost:5000/?param=a&param=bbb

I should expect an output of [‘a’, ‘bbb’] except Flask seems to only accept the first param and ignore the rest.

Is this a limitation of Flask? Or is it by design?

Asked By: John Jiang

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Source

Answer 1

You can use getlist, which is similar to Django’s getList but for some reason isn’t mentioned in the Flask documentation:

return str(request.args.getlist('param'))

The result is:

[u'a', u'bbb']

Use request.args if the param is in the query string (as in the question), request.form if the values come from multiple form inputs with the same name. request.values combines both, but should normally be avoided for the more specific collection.

Answered By: Blender

Answer 2

If you used $('form').serialize() in jQuery to encode your form data, you can use request.form['name'] to get data, but note that when multiple input elements’ names are the same, request.form['name'] will only get the first matched item. So I checked the form object from the Flask API, and I found this. Then I checked the MultiDict object, and I found the function getlist('name').

If there are multiple inputs with the same name, try this method: request.form.getlist('name')

Answered By: Vin

Answer 3

One more way is that you can use one key and one value that holds multiple values and then in the server you can split and do what ever you want .Hope this Helps somewone

http://localhost/api/products/filters?Manufacturer=Dell|HP|HUAWEI|Lenovo

OR

http://localhost/api/products/filters?Manufacturer=Dell_HP_HUAWEI_Lenovo

OR

http://localhost/api/products/filters?Manufacturer=Dell__HP__HUAWEI__Lenovo

Answered By: user7956520

Answer 4

Another option is to use a flat json structure with request.args. Because sometimes you simply do not know the parameter beforehand and you cannot use .getlist().

arguments = request.args.to_dict(flat=False)

# Get a specific parameter
param = arguments.get('param')
print(param)

# Get all the parameters that have more than one value
for field, values in arguments.items():
    if len(values) > 1:
        print(values)

Answered By: Nebulastic

Get multiple request params of the same name

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