在FieldList中动态调整的表单 [英] Dynamically adjusted forms inside FieldList

问题描述

我正在使用Flask和Flask-WTF，我需要创建一个包含几个具有相似结构的块(子表单)的表单(例如具有一个SelectField和一个TextAreaField的子表单).正如文档建议一样，我可以使用与FieldList一起实现此目标.但是，我需要动态调整SelectField(根据数据库中的值在运行时更改其choice).现在，文档建议

I'm using Flask and Flask-WTF and I need to create a form that contains several blocks (subforms) of a similar structure (like a subform with one SelectField and one TextAreaField). As the docs suggest, I can use FormField together with FieldList to achieve this goal. However, I need to tweak my SelectField's dynamically (changing their choices at runtime according to values in the database). The docs now suggest

请注意，choices关键字仅被评估一次，因此，如果要创建动态下拉列表，则需要在实例化后将选择列表分配给字段.

Note that the choices keyword is only evaluated once, so if you want to make a dynamic drop-down list, you’ll want to assign the choices list to the field after instantiation.

可以在此处找到这种方法的示例.但是，FormField接受的是form_class，而不是实例(至少根据文档显示)，因此看来这两个配方不能很好地配合使用.

One can find an example of this approach here. However, FormField is accepting form_class, not an instance (at least, according to the docs), so it seems that these two recipes do not play well together.

还有其他想法吗?

推荐答案

好吧，这比我想象的要容易.您必须使用空白选项创建这些子表单，创建它们的列表，然后在列表项中调整选项.

Okay, it's easier than I thought. You have to create those subforms with empty choices, create list of them and then adjust choices inside the list items.

class UserForm(wtforms.Form):
# must inherit from wtforms.Form, not flask-WTForms'
# see http://stackoverflow.com/questions/15649027/wtforms-csrf-flask-fieldlist
    first_name = StringField('First Name', [validators.DataRequired()])
    last_name = StringField('Last Name', [validators.DataRequired()])
    accepted_policy = BooleanField('Accept Policy')
    experience = SelectField('Experience', coerce=int)

class UsersForm(Form):
    users = FieldList(FormField(UserForm), min_entries=2)

@app.route('/', methods=['GET', 'POST'])
def hello_world():

    form = UsersForm(users=[{}, {}, {}])
    form.users[0].experience.choices=[(1, 'One'), (2, 'Two')]
    form.users[1].experience.choices = [(1, 'Uno'), (2, 'Du')]
    form.users[2].experience.choices = [(0, 'Zero')]
    return render_template("hello.html", form=form)

这是一个模板:

{% macro render_field(field) %}
  <dt>{{ field.label }}
  <dd>{{ field(**kwargs)|safe }}
  {% if field.errors %}
    <ul class=errors>
    {% for error in field.errors %}
      <li>{{ error }}</li>
    {% endfor %}
    </ul>
  {% endif %}
  </dd>
{% endmacro %}

<form method=post>
  <dl>
      {{ form.hidden_tag()}}
      {%  for user_entry_form in form.users %}
          {{ user_entry_form.name }}
    {{ render_field(user_entry_form.first_name) }}
    {{ render_field(user_entry_form.last_name) }}
    {{ render_field(user_entry_form.experience) }}
      {%  endfor %}
  </dl>
  <p><input type=submit value=Go!>
</form>

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