I have a Flask application that uses WTForms for user input. It uses a SelectMultipleField
in a form. I can't seem to get the app to POST all items in the field when selected; it only sends the first item selected regardless of how many the user selects.
The Flask documentation says this about the data sent from this field type, but I don't see this behavior:
The data on the SelectMultipleField is stored as a list of objects, each of which is checked and coerced from the form input.
Here's a complete, minimal Flask app that illustrates this:
#!/usr/bin/env python
from flask import Flask, render_template_string, request
from wtforms import Form, SelectMultipleField
application = app = Flask('wsgi')
class LanguageForm(Form):
language = SelectMultipleField(u'Programming Language', choices=[('cpp', 'C++'), ('py', 'Python'), ('text', 'Plain Text')])
template_form = """
{% block content %}
<h1>Set Language</h1>
<form method="POST" action="/">
<div>{{ form.language.label }} {{ form.language(rows=3, multiple=True) }}</div>
<button type="submit" class="btn">Submit</button>
</form>
{% endblock %}
"""
completed_template = """
{% block content %}
<h1>Language Selected</h1>
<div>{{ language }}</div>
{% endblock %}
"""
@app.route('/', methods=['GET', 'POST'])
def index():
form = LanguageForm(request.form)
if request.method == 'POST' and form.validate():
print "POST request and form is valid"
language = request.form['language']
print "languages in wsgi.py: %s" % request.form['language']
return render_template_string(completed_template, language=language)
else:
return render_template_string(template_form, form=form)
if __name__ == '__main__':
app.run(debug=True)
Flask returns request.form as a werkzeug MultiDict object. This is kind of like a dictionary, only with traps for the unwary.
http://flask.pocoo.org/docs/api/#flask.request http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.MultiDict
MultiDict implements all standard dictionary methods. Internally, it saves all values for a key as a list, but the standard dict access methods will only return the first value for a key. If you want to gain access to the other values, too, you have to use the list methods.
However, I think there's an easier way. Can you do me a favor and try replacing:
language = request.form['language']
with
language = form.language.data
and see if that's any different? WTForms should handle the MultiDict object and just return a list for you since you've bound form data to it.