关于python：Flask应用程序将WTForms与SelectMultipleField一起使用

Flask App Using WTForms with SelectMultipleField

我有一个Flask应用程序，该应用程序使用WTForms作为用户输入。它使用SelectMultipleField形式。选择后，我似乎无法让该应用发布该字段中的所有项目；它只会发送选择的第一个项目，而不管用户选择了多少个项目。

Flask文档说明了有关从此字段类型发送的数据的信息，但我没有看到这种现象：

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，它说明了这一点：

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#!/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 %}
Set Language

<form method="POST" action="/">
{{ form.language.label }} {{ form.language(rows=3, multiple=True) }}
<button type="submit" class="btn">Submit</button>
</form>
{% endblock %}

"""

completed_template ="""
{% block content %}
Language Selected

{{ language }}

{% 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作为werkzeug MultiDict对象返回request.form。这有点像一本字典，只为那些粗心的人设陷阱。

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.

但是，我认为有一种更简单的方法。
您能帮我一个忙，然后尝试更换：

1	language = request.form['language']

与

1	language = form.language.data

看看有什么不同吗？ WTForms应该处理MultiDict对象，并因为将表单数据绑定到该对象而只为您返回一个列表。