List of query params with Flask request.args

Question

I am trying to pass comma separated query parameters to a Flask endpoint.

An example URI would be:

localhost:3031/someresource#?status=1001,1002,1003

Answer 1

Its not uncommon REST API design to have commas to pass multiple values for the same key - makes it easier for the user. You're parsing GET args anyway, parsing strings is not that much more hacky. You can choose to raise a 400 HTTP error if their string with commas isn't well formatted.

Some other languages (notably PHP) support 'array' syntax, so that is used sometimes:

/request?status[]=1000&status[]=1001&status[]=1002

The flask variant getlist expects multiple keys:

from flask import Flask, request

app = Flask(__name__)

@app.route('/')
def status():
    first_status = request.args.get("status")
    statuses = request.args.getlist("status")
    return "First Status: '{}'\nAll Statuses: '{}'".format(first_status, statuses)

❯ curl "http://localhost:5000?status=5&status=7"
First Status: '5'
All Statuses: '['5', '7']'

There's no standard for this, how multiple GET args are parsed/passed depends on which language/framework you're using; flask is built on werkzeug so it allows this style, but you'll have to look it up if you switch away from flask.