Flask App将WTForms与SelectMultipleField一起使用 [英] Flask App Using WTForms with SelectMultipleField

问题描述

我有一个Flask应用程序，该应用程序使用WTForms进行用户输入.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；它仅发送选择的第一个项目，而不管用户选择了多少个项目.

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.

Flask文档谈到了从该字段类型发送的数据，但是我没有看到此行为:

The Flask documentation says this about the data sent from this field type, but I don't see this behavior:

SelectMultipleField上的数据存储为对象列表， 每一项都从表单输入中进行检查和强制.

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:

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)

推荐答案

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.

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

http://flask.pocoo.org/docs/api/#flask.request http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.MultiDict

MultiDict实现所有标准的字典方法.在内部，它将键的所有值保存为列表，但是标准dict访问方法将仅返回键的第一个值.如果您也想访问其他值，则必须使用列表方法.

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:

However, I think there's an easier way. Can you do me a favor and try replacing:

language =  request.form['language']

使用

language =  form.language.data

看看那有什么不同吗? 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.

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.

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