Question

我有一些表单字段，我想根据是否满足某个条件来包含/排除。我知道如何包含和排除表单元素，但是当我希望它根据函数的结果显示元素时，我很难做到。

这是我的表格：

class ProfileForm(ModelForm):
    # this_team = get Team instance from team.id passed in
    # how?

    def draft_unlocked(self):
        teams = Team.objects.order_by('total_points')
        count = 0
        for team in teams:
            if team.pk == this_team.pk:
                break
            count += 1

        now = datetime.datetime.now().weekday()
        if now >= count:
            # show driver_one, driver_two, driver_three
        else:
            # do not show driver_one, driver_two, driver_three

class Meta:
    model = Team

我想要完成的是，根据总积分的排名，团队不应该在指定的日期之前改变他们的驾驶员。在比赛中，排名最后一支球队可以在周一添加/减少一名车手，倒数第二支球队可以在周二加/减，依此类推...

所以第一个问题 - 如何从传入的id中获取表单内部的Team实例。而且，如何根据draft_unlocked（）的结果包含/排除。

或许有更好的方法可以做到这一切？

非常感谢大家。

Answer 1

这实际上非常简单（条件字段设置） - 这是一个简单的例子：

from django.forms import Modelform
from django.forms.widgets import HiddenInput

class SomeForm(ModelForm):

    def __init__(self, *args, **kwargs):
        # call constructor to set up the fields. If you don't do this 
        # first you can't modify fields.
        super(SomeForm, self).__init__(*args, **kwargs)

        try:
            # make somefunc return something True
            # if you can change the driver.
            # might make sense in a model?
            canchangedriver = self.instance.somefunc()                          
        except AttributeError:
            # unbound form, what do you want to do here?
            canchangedriver = True # for example?

        # if the driver can't be changed, use a input=hidden
        # input field.
        if not canchangedriver:
            self.fields["Drivers"].widget = HiddenInput()

    class Meta:
        model = SomeModel

所以，关键点是：

self.instance表示绑定对象。我相信它是作为命名参数传递的，因此在kwargs中，父构造函数用来创建self.instance。
您可以在调用父构造函数后修改字段属性。
小部件是表单的显示方式。 HiddenInput基本上意味着<input type="hidden" .../>。

有一个限制;如果修改提交的POST / GET数据，我可以篡改输入以更改值。如果您不希望发生这种情况，需要考虑的事项是覆盖表单的验证（clean（））方法。请记住，Django中的所有内容都只是对象，这意味着您可以实际修改类对象并随机添加数据（虽然它不会被保留）。所以在__init__你可以：

self.instance.olddrivers = instance.drivers.all()

然后用你所说的形式的干净方法：

def clean(self):
    # validate parent. Do this first because this method
    # will transform field values into model field values.
    # i.e. instance will reflect the form changes.
    super(SomeForm, self).clean()

    # can we modify drivers?
    canchangedriver = self.instance.somefunc() 

    # either we can change the driver, or if not, we require 
    # that the two lists are, when sorted, equal (to allow for 
    # potential non equal ordering of identical elements).

    # Wrapped code here for niceness
    if (canchangedriver or 
                   (sorted(self.instance.drivers.all()) == 
                    sorted(self.instance.olddrivers))):  
        return True
    else:
        raise ValidationError() # customise this to your liking.

Answer 2

您可以通过添加自己的init来执行所需的操作，在实例化表单类时可以传入id：

class ProfileForm(ModelForm):
    def __init__(self, team_id, *args, **kwargs):
        super(ProfileForm, self).__init__(*args, **kwargs)

        this_team = Team.objects.get(pk=team_id)

        teams = Team.objects.order_by('total_points')
        count = 0
        for team in teams:
            if team.pk == this_team.pk:
                break
            count += 1

        now = datetime.datetime.now().weekday()
        if now >= count:
            # show driver_one, driver_two, driver_three
        else:
            # do not show driver_one, driver_two, driver_three

class Meta:
    model = Team

#views.py
def my_view(request, team_id):
    profile_form = ProfileForm(team_id, request.POST or None)
    #more code here

希望能帮到你。

django：根据条件排除某些表单元素

2 个答案: