monkut monkut - 1 year ago 193
Python Question

Limit the queryset of entries displayed for a django admin Inline

In django admin, using django 1.2, i'm trying to add a InlineModelAdmin to apply a comment on save when a change is made to an entry. (An entry is expected to have a "ChangeComment" for every edit).

I don't want to show previous entries, so I am trying to force the ChangeCommentInline's formset.queryset to be empty, by creating NoCommentsInlineFormset and assigning the formset in my ChangeCommentInline, but is still returning existing entries.

Note - In the link above they use BaseModelFormset, I'm using BaseInlineFormset, which I expect may be the issue. If I swap out BaseInlineFormset with BaseModelFormset I get an error about "instance" not existing.

class NoCommentsInlineFormset(models.BaseInlineFormset):
def __init__(self, *args, **kwargs):
super(NoCommentsInlineFormset, self).__init__(*args, **kwargs)
self.queryset = ChangeComment.objects.none()

class ChangeCommentInline(admin.StackedInline):
model = ChangeComment
extra = 1
exclude = ("user", )
formset = NoCommentsInlineFormset

def save_model(self, request, obj, form, change):
"""auto-assign logined in user to comment"""
if not change:
obj.user = request.user

class EntryAdmin(admin.ModelAdmin):
inlines = (ChangeCommentInline, )

Can limiting the ChangeComment entries displayed in the Inline be done, or is there a better way to handle this?

Answer Source

As benjaoming mentioned in the comments, it was necessary to override the get_queryset() method in the InlineModelAdmin. It was not necessary to override and attach a new formset to the InlineModelAdmin definition as I initially thought.

Here is the resulting implementation:

class ChangeCommentInline(admin.StackedInline):
    """For allowing logged in user to add change comment"""
    model = ChangeComment
    extra = 1
    exclude = ("user", ) # auto-update user field in save_formset method of parent modeladmin.

    def get_queryset(self, request):
        """Alter the queryset to return no existing entries"""
        # get the existing query set, then empty it.
        qs = super(ChangeCommentInline, self).get_queryset(request)
        return qs.none()  
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