python - Flask WTForms BooleanField UnboundField

Question

我正在编写一个脚本，通常从数据库中检索 5 行，我想将其显示为复选框列表。

但它无法正确显示:它显示“UnboundField ”

form.py

class ExampleForm(FlaskForm):
    [...query & results...]
    for line in results_sql:
        list_checkbox[line.label] = BooleanField(line.label)

routes.py

@bp.route('/example')
def example():
    form = ExampleForm()
    return render_template("index.html", form=form)

index.html

<table class="table table-bordered table-condensed">
    {% for checkbox in form.list_checkbox %}
    <tr>
        <td>{{ checkbox }}</td>
        <td>{{ form.list_checkbox[checkbox ] }}</td>
    </tr>
    {% endfor %}
</table>

结果:

Answer 1

您已将字段放入嵌套字典中。该表单无法绑定(bind)此类字段，因为它无法处理任意容器。

相反，您需要将字段放在 field enclosure 中。我会使用 FormField() field指向嵌套的 Form 类。您可以通过调用 BaseForm() constructor 来生成嵌套的 Form 类。 :

What BaseForm provides is a container for a collection of fields, which it will bind at instantiation, and hold in an internal dict. Dict-style access on a BaseForm instance will allow you to access (and modify) the enclosed fields.

然后，当您创建 ExampleForm() 类的实例时，它将绑定(bind) FormField 字段，然后该字段又创建嵌套表单的实例对象，然后绑定(bind)您提供的每个字段 BaseForm()

因为调用 BaseForm(fields) 将创建一个表单实例，因此您需要先将其包装在函数中，然后才能将其用作嵌套表单:

def form_from_fields(fields):
    def create_form(prefix='', **kwargs):
        form = BaseForm(fields, prefix=prefix, meta=FlaskForm.Meta)
        form.process(**kwargs)
        return form
    return create_form

class ExampleForm(FlaskForm):
    # ...

    list_checkbox = FormField(
        form_from_fields(
            [(line.label, BooleanField(line.label)) for line in results_sql]
        )
    )

BaseForm() 不像 Form 类那样接受任何数据，因此您需要传递 FormField() 的参数返回实例之前，将 create 实例传递给 .process() 方法。

渲染时迭代 list_checkbox 字段时，您可以直接获取字段并从字段对象中获取标签:

<table class="table table-bordered table-condensed">
    {% for checkbox in form.list_checkbox %}
    <tr>
        <td>{{ checkbox.label }}</td>
        <td>{{ checkbox }}</td>
    </tr>
    {% endfor %}
</table>

演示(使用基础 WTForms 库，但 Flask-WTF 流程相同):

>>> from wtforms.form import BaseForm, Form
>>> from wtforms.fields import BooleanField, FormField
>>> fields = ['Calendrier', 'Commentaire', 'Dessin', 'Ex-libris', 'Gravure']
>>> def form_from_fields(fields):
...     def create_form(prefix='', **kwargs):
...         form = BaseForm(fields, prefix=prefix)
...         form.process(**kwargs)
...         return form
...     return create_form
...
>>> class ExampleForm(Form):
...     list_checkbox = FormField(form_from_fields([(field, BooleanField(field)) for field in fields]))
...
>>> form = ExampleForm()
>>> form.list_checkbox
<wtforms.fields.core.FormField object at 0x1232a76d8>
>>> list(form.list_checkbox)
[<wtforms.fields.core.BooleanField object at 0x1232a77f0>, <wtforms.fields.core.BooleanField object at 0x1232a78d0>, <wtforms.fields.core.BooleanField object at 0x1232a7978>, <wtforms.fields.core.BooleanField object at 0x1232a7a20>, <wtforms.fields.core.BooleanField object at 0x1232a7ac8>]
>>> print(*form.list_checkbox, sep='\n')
<input id="list_checkbox-Calendrier" name="list_checkbox-Calendrier" type="checkbox" value="y">
<input id="list_checkbox-Commentaire" name="list_checkbox-Commentaire" type="checkbox" value="y">
<input id="list_checkbox-Dessin" name="list_checkbox-Dessin" type="checkbox" value="y">
<input id="list_checkbox-Ex-libris" name="list_checkbox-Ex-libris" type="checkbox" value="y">
<input id="list_checkbox-Gravure" name="list_checkbox-Gravure" type="checkbox" value="y">

FormField() 字段还确保您可以为表单设置默认值，或者确保您可以在再次发布表单时访问数据集:

>>> form = ExampleForm(list_checkbox={'Calendrier': True})
>>> print(form.list_checkbox['Calendrier'])
<input checked id="list_checkbox-Calendrier" name="list_checkbox-Calendrier" type="checkbox" value="y">
>>> print(form.list_checkbox['Commentaire'])
<input id="list_checkbox-Commentaire" name="list_checkbox-Commentaire" type="checkbox" value="y">