Django ModelForm ChoiceField 不显示实例数据 [英] Django ModelForm ChoiceField not displaying instance data

问题描述

我有一个 ModelForm 类，我在其中将几个字段设置为 ChoiceField.对于我的一个视图，我想从我的 ModelForm 类中创建一个表单，该类从数据库中的模型实例中提取(像这样):

I have a ModelForm class in which I set a couple of the fields as ChoiceField. For one of my views, I'd like to create a form from my ModelForm class that pulls from an instance of my model in the database (like so):

form = MyModel(instance=model_instance)

当我这样做然后在模板中呈现表单时，我注意到大多数字段都预先填充了从模型实例中提取的值，这正是我想要的.但是，对于两个 ChoiceField 字段，情况并非如此.这些呈现为没有选择特定选项的下拉选择菜单.

When I do this and then render the form in a template, I've noticed that most of the fields are pre-populated with values pulled from the model instance, which is what I want. However, this isn't the case for two ChoiceField fields. These render as drop-down select menus with no specific option selected.

奇怪的是，如果我没有在 ModelForm 类中将这两个字段定义为 ChoiceField 类型，它们会在 HTML 中呈现为普通文本输入字段，并使用数据库值进行预填充.但是当我定义它们以便它们在 HTML 中显示为选择选项输入字段时，没有预先选择任何内容.我可以更改此设置以便预先选择数据库中的值吗?

What's strange is if I don't define those two fields as ChoiceField-type in my ModelForm class, they render as normal text input fields in HTML and pre-populate using the database values. But when I define them so they show up as select-option input fields in HTML, nothing is pre-selected. Can I change this so that the values from the database are pre-selected?

这里要求的是我的模型和表单的代码:

As requested here is the code for my model and form:

class App(models.Model):
    CODES = (
        (u'a',u'annual'),
        (u'm',u'monthly'),
        (u'w',u'weekly')
    )
    code = models.CharField(max_length=1, choices=CODES)
    start_time = models.TimeField(blank=True, null=True)
    end_time = models.TimeField(blank=True, null=True)


class AppForm(ModelForm):
    CODES = (
        (u'',u'Please select code'),
        (u'a',u'annual'),
        (u'm',u'monthly'),
        (u'w',u'weekly')
    )
    TIMES = (
        (u'00:00',u'All Day'),
        (u'12:00',u'Noon')
    )
    start_time = forms.ChoiceField(required=False, choices=TIMES)
    end_time = forms.ChoiceField(required=False, choices=TIMES)
    code = forms.ChoiceField(choices=CODES, label='Type')

    class Meta:
        model = App

有趣的是，code 字段在呈现为 HTML 时预选了模型实例值.我想知道模型定义中的 choices 参数在这里是否有所不同?

Interestingly, code field has the model instance value preselected just fine when rendered as HTML. I wonder if having the choices argument in the model definition makes the difference here?

更新:我刚刚注意到，如果我在 python manage.py shell 中拉出一个 App 实例，如下所示:

UPDATE: I just noticed that if I pull up an App instance in the python manage.py shell like so:

a = App.objects.get(id=16)
a.start_time

我得到一个类似 datetime.time(12, 0) 的值.但是在 Django 管理员中，当我查看所有 App 实例时，它们都在 start_time 和 <代码>结束时间.为什么会这样?

I get a value like datetime.time(12, 0). But in the Django admin, when I'm looking at all of the App instances, all of them show (None) under start_time and end_time. Why would that be?

推荐答案

响应您的更新:您的时间字符串匹配默认时间字符串 HH:MM 格式.就像用户会在 12:00 从网站手动输入它们一样.这些值在模型保存时被解析并转化为时间(在真正验证时).

In response to your update : your times strings match default time string HH:MM format. Just like a user would enter them from website manually 12:00. The values get parsed and turned into time at model save (at validating really).

当你加载模型时 - 当然从对象加载的初始值匹配字段的 (models.TimeField) 类型.

And when you load model - then of course the initial values loaded from object match the field's (models.TimeField) type.

如果您将 TIMES 替换为

If you replace your TIMES with

    (datetime.time(0,0),u'All Day'),
    (datetime.time(12,0),u'Noon')

你的麻烦应该结束了.

艾伦

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