python – 使用带有SelectMultipleField的WTForms的Flask应用程

Flask documentation说明了这个字段类型发送的数据,但我没有看到这种行为：

The data on the SelectMultipleField is stored as a list of objects,
each of which is checked and coerced from the form input.

这是一个完整的,最小的Flask应用程序,说明了这一点：

#!/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)