DateTimeField doesn't show in admin system

问题:

How come my "date" field doesn't come up in the admin system?

In my admin.py file i have

from django.contrib import admin
from glasses.players.models import *
admin.site.register(Rating)

and the Rating model has a field called "date" which looks like this

date = models.DateTimeField(editable=True, auto_now_add=True)

However within the admin system, the field doesn't show, even though editable is set to True.

Does anyone have any idea?

回答1:

I believe to reason lies with the auto_now_add field.

From this answer:

Any field with the auto_now attribute set will also inherit editable=False and therefore will not show up in the admin panel.

Also mentioned in the docs:

As currently implemented, setting auto_now or auto_now_add to True will cause the field to have editable=False and blank=True set.

This does make sense, since there is no reason to have the field editable if it's going to be overwritten with the current datetime when the object is saved.

回答2:

If you really want to see date in the admin panel, you can add readonly_fields in admin.py:

class RatingAdmin(admin.ModelAdmin):
    readonly_fields = ('date',)

admin.site.register(Rating,RatingAdmin)

Any field you specify will be added last after the editable fields. To control the order you can use the fields options.

Additional information is available from the Django docs.

回答3:

Major Hack:

If you really need to do this (as I do) you can always hack around it by immediatley setting the field to be "editable" defining the field as follows:

class Point(models.Model):
  mystamp=models.DateTimeField("When Created",auto_now_add=True)
  mystamp.editable=True

This will make the field editable, so you can actually alter it. It seems to work fine, at least with the mysql backing engine. I cannot say for certian if other backing stores would make this data immutable in the database and thus cause a problem when editing is attempted, so use with caution.

回答4:

Depending on your specific needs, and any nuances in difference in behavior, you could do the following:

from django.utils.timezone import now

class MyModel(models.Model):
    date = models.DateTimeField(default=now)

The default field can be used this way: https://docs.djangoproject.com/en/dev/ref/models/fields/#default

The default value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created.

This does not set editable to False

回答5:

It might have to do with the auto_now_add being true. Perhaps instead of that parameter to capture the date on add, you could override the model save method to insert the datetime when the id is null.

class Rating(models.Model):

    ....
    def save(self, *args, **kwargs)
        if not self.id: 
            self.date = datetime.datetime.now()

回答6:

If you want any field to be visible in the list of all your entries (when you click on a model in the admin people) and not when you open that particular entry then -

class RatingAdmin(admin.ModelAdmin):
    list_display = ('name', 'date') 

admin.site.register(Rating, RatingAdmin)

'name' being your main field or any other field you want to display in the admin panel.

This way you can specify all the columns you want to see.

回答7:

You can not do that, check the documentation

auto_now and auto_now_add are all non-editable fields and you can not override them...