python - Getting value from select tag using flask

Question

I'm new to Flask and I'm having trouble getting the value from my select tag. I have tried request.form['comp_select'] which returns a Bad Request. However, when I try using request.form.get('comp_select'), my return page returns a blank list "[]".

My html:

<form class="form-inline" action="{{ url_for('test') }}">
  <div class="form-group">
    <div class="input-group">
        <span class="input-group-addon">Please select</span>
            <select name="comp_select" class="selectpicker form-control">
              {% for o in data %}
              <option value="{{ o.name }}">{{ o.name }}</option>
              {% endfor %}                                              
            </select>
    </div>
    <button type="submit" class="btn btn-default">Go</button>
  </div>
</form>

My app.py:

@app.route("/test" , methods=['GET', 'POST'])
def test():
    select = request.form.get('comp_select')
    return(str(select)) # just to see what select is

Sorry in advance if my formatting is off for the post (also new to Stack Overflow).

Answer 1

It's hard to know for certain from what you've provided, but I believe you need to add method="POST" to your <form> element.

From the flask doc for the request object:

To access form data (data transmitted in a POST or PUT request) you can use the form attribute. ... To access parameters submitted in the URL (?key=value) you can use the args attribute.

So, if you submit your forms via POST, use request.form.get(). If you submit your forms via GET, use request.args.get().

This app behaves the way you want it to:

flask_app.py:

#!/usr/bin/env python
from flask import Flask, flash, redirect, render_template, 
     request, url_for

app = Flask(__name__)

@app.route('/')
def index():
    return render_template(
        'index.html',
        data=[{'name':'red'}, {'name':'green'}, {'name':'blue'}])

@app.route("/test" , methods=['GET', 'POST'])
def test():
    select = request.form.get('comp_select')
    return(str(select)) # just to see what select is

if __name__=='__main__':
    app.run(debug=True)

templates/index.html

<form class="form-inline" method="POST" action="{{ url_for('test') }}">
  <div class="form-group">
    <div class="input-group">
        <span class="input-group-addon">Please select</span>
            <select name="comp_select" class="selectpicker form-control">
              {% for o in data %}
              <option value="{{ o.name }}">{{ o.name }}</option>
              {% endfor %}
            </select>
    </div>
    <button type="submit" class="btn btn-default">Go</button>
  </div>
</form>