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Here is how my model and admin looks like: Model

class Event(models.Model):
    id = models.AutoField(primary_key=True)
    title = models.CharField(max_length=120)
    description = models.TextField(default="", blank=True)
    start = models.DateTimeField(default=datetime.now)
    end = models.DateTimeField(blank=True, null=True)
    parent_event = models.ForeignKey(
        to="Event", on_delete=models.CASCADE, blank=True, null=True)

Admin

EVENT_DISPLAYABLE_FIELDS = ["title", "start", "end"]


# Will display and allow adding inline sub events
# in tabular format
class SubEventInline(admin.TabularInline):
    model = Event
    # Do not add empty extra inlines
    extra = 0
    # Will allow only the fields listed below
    # to be displayed and edited
    fields = EVENT_DISPLAYABLE_FIELDS
    # Will allow navigating to its edit page
    show_change_link = True


# Will display the Event edit page on admin site
class EventAdmin(admin.ModelAdmin):
    # Will only display the fields listed below
    # on the main events page
    list_display = EVENT_DISPLAYABLE_FIELDS
    list_display.append('preview')
    # Enables sub events to be displayed or allowed
    # to be added in the current event's edit page
    inlines = [
        SubEventInline,
    ]

    def preview(self, event):
        url = reverse('events', kwargs={'id': event.id})
        return format_html('<a class="button" href="{}">Preview</a>', url)

    preview.short_description = 'Preview Event'
    preview.allow_tags = True

The above correctly displays the button on the list display view, but when clicking on any event to navigate to it's change/edit page, django throws an error:

django.core.exceptions.FieldError: Unknown field(s) (preview) specified for Event

Please help me find out what am I missing here?

I tried using exclude in TabularInline but Django then throws a different error message saying

Keyerror "preview"

I also tried adding a new non-persistent field to the event model but it did not work.

Ankur Goyal
  • 1

0 Answers0