Python 使用 wtforms 和 flask 在选择字段中设置默认值
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Setting a default value in the selectfield, using wtforms and flask
提问by kfk
I am creating a product edit form and I need the form to be pre-populated with the previous data.
我正在创建一个产品编辑表单，我需要用以前的数据预先填充该表单。
I am doing the following:
我正在做以下事情：
Product(form):
product = TextField('name')
category = SelectField('category', choice=[(1,'one'),(2,'two')])
In the view:
在视图中：
form.product.data = 'A product name from the database'
form.category.data = 'a category name' #This does not work
The issue is with the SelectField.
问题出在 SelectField 上。
I understand there is a 'default' value I can set on SelectField. However, this happens in the form definition class and there I do not have the query object from sqlalchemy yet.
我知道我可以在 SelectField 上设置一个“默认”值。但是，这发生在表单定义类中，我还没有来自 sqlalchemy 的查询对象。
So, is there a way to append a default on selectfield on run time?
那么，有没有办法在运行时在选择字段上附加默认值？
采纳答案by tbicr
If you want set default value to render page with form you can create own form or set value:
如果您想设置默认值以使用表单呈现页面，您可以创建自己的表单或设置值：
class Product(Form):
product = TextField('name')
category = SelectField('category', choices=[(1,'one'),(2,'two')])
# create instance with predefined value:
form1 = Product(category=2)
# form1.product == <input id="product" name="product" type="text" value="">
# form1.category == <select id="category" name="category">
# <option value="1">one</option>
# <option selected value="2">two</option>
# </select>
# from1.product.data == None
# form1.category.data == 2
# create own form if it need many times:
Product2 = type('Product2', (Product,), {
'category': SelectField('category', default=2, choices=[(1,'one'),(2,'two')])
})
form2 = Product2()
# form2.product == <input id="product" name="product" type="text" value="">
# form2.category == <select id="category" name="category">
# <option value="1">one</option>
# <option selected value="2">two</option>
# </select>
# from2.product.data == None
# form2.category.data == 2
If you want set default form data on request:
如果您想根据要求设置默认表单数据：
with app.test_request_context(method='POST'):
form = Product(request.form)
# form5.category.data == None
form = Product(request.form, category=2)
# form5.category.data == 2
with app.test_request_context(method='POST', data={'category': 1}):
form = Product(request.form)
# form5.category.data == 1
form = Product(request.form, category=2)
# form5.category.data == 1
回答by AlexLordThorsen
From the WTForms documentation
来自 WTForms 文档
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.
请注意，choices 关键字只计算一次，因此如果您想制作动态下拉列表，您需要在实例化后将选择列表分配给字段。
Product(form):
product = TextField('name')
category = SelectField('category')
And then in your view say
然后在你看来说
form.category.choices = [list of choices with chosen data]
More detail found here: http://wtforms.simplecodes.com/docs/0.6.1/fields.html#wtforms.fields.SelectField
在这里找到更多细节：http: //wtforms.simplecodes.com/docs/0.6.1/fields.html#wtforms.fields.SelectField
