python - 如何从使用 WTForm 构建的表单中清空数值

Question

我有这个小 Flask 程序。它需要用户的姓名和年龄，然后打印一条消息。真的很简单，因为我刚刚开始使用 Python 和 Flask。

from flask import Flask, render_template
from flask.ext.bootstrap import Bootstrap 
from flask.ext.wtf import Form 
from wtforms import StringField, IntegerField, SubmitField
from wtforms.validators import Required, Length, NumberRange

app = Flask(__name__)
app.config['SECRET_KEY'] = 'top secret!'
bootstrap = Bootstrap(app)

class NameForm(Form):
    name = StringField('What is your name?', validators = [Required(), Length(1, 16)])
    age  = IntegerField('How old are you?', validators = [Required(), NumberRange(min=1, max=99, message="Should be between 1 and 99")])

    submit = SubmitField('Submit')

@app.route('/', methods=['GET', 'POST'])
def index():
    name = None
    age  = None
    form = NameForm()
    if form.validate_on_submit():
        name = form.name.data
        age  = form.age.data
        form.age.raw_data = None
        form.name.data = ''

    return render_template('index.html', form = form, name = name, age = age)

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

而且，对于 HTML 模板，我有:
{% 扩展 "bootstrap/base.html"%}

{% block title %}Form Example{% endblock %}

{% block navbar %}
    <nav class="navbar navbar-inverse" role="navigation">
        <div class="container">
            <a href="{{ url_for('index') }}" class="navbar-brand">Hello</a>
        </div>
    </nav>
{% endblock %}

{% block content %}
    <div class="container">
        <form method="POST" action="">
            {{ form.name.label }} {{ form.name(size=16, class='name-field') }}
            {% for error in form.name.errors %}
                {{ error }}
            {% endfor %}

            <br>

            {{ form.age.label }} {{ form.age(class='age-field') }}
            {% for error in form.age.errors %}
                {{ error }}
            {% endfor %}

            <br />
            {{ form.submit() }}
            {{ form.hidden_tag() }}
        </form>
        {% if name %}
            <h1>Hello, {{ name.capitalize() }}</h1>
            <h2>You're {{ age }} years old.</h2>
        {% endif %}
    </div>
{% endblock %}

我的问题是，提交表单后，姓名输入被清空，但年龄输入没有。为什么？如何清空数字字段？

谢谢。

Answer 1

感谢您提出明确的问题 - 我能想到的将表单清空的最简单方法就是创建它并告诉它忽略请求表单数据。

@app.route('/', methods=['GET', 'POST'])
def index():
    form = NameForm()  # Auto-populates from request data.
    name = None
    age = None
    if form.validate_on_submit():
        name = form.name.data
        age  = form.age.data

        # Lets now create a form, but ignore the request data, so it's empty:
        form = NameForm(formdata=None)
    return render_template('index.html', form = form, name = name, age = age)

另外，我注意到您正在使用 Required()正在被 DataRequired() 取代并且会在 WTF v3 中消失，所以你现在可能想开始使用它，你 future 的自己会感谢你!