使用wtforms和flask在selectfield中设置默认值

Question

我正在创建一个产品编辑表单,我需要预先填充以前的数据表单.

我正在做以下事情:

Product(form):
    product = TextField('name')
    category = SelectField('category', choice=[(1,'one'),(2,'two')])

在视图中:

form.product.data = 'A product name from the database'
form.category.data = 'a category name' #This does not work

问题出在SelectField上.

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,并且我还没有来自sqlalchemy的查询对象.

那么,有没有办法在运行时在selectfield上添加默认值？

Answer 1

如果要将默认值设置为使用表单呈现页面,则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

如果要根据请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

Answer 2

来自WTForms文档

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

Product(form):
    product = TextField('name')
    category = SelectField('category')

然后在你看来说

form.category.choices = [list of choices with chosen data]

更多详细信息请访问:http: //wtforms.simplecodes.com/docs/0.6.1/fields.html#wtforms.fields.SelectField