Django. Admin Tabular Inline initial data

admin.py

from django.utils.functional import curry

class DetailsInline(admin.TabularInline):
    model = Details
    # formset = DetailsFormset
    extra = 3

    def get_formset(self, request, obj=None, **kwargs):
        initial = []
        if request.method == "GET":
            initial.append({
                'label': 'first name',
            })
        formset = super(DetailsInline, self).get_formset(request, obj, **kwargs)
        formset.__init__ = curry(formset.__init__, initial=initial)
        return formset

models.py

class Employee(models.Model):
    username = models.CharField(_('Username'), max_length=150, null=False, blank=False)
    email = models.CharField(_('Email'), max_length=150, null=False, blank=False)

class Details(models.Model):
    employee = models.ForeignKey(Employee, verbose_name=_('Employee'), blank=False, null=False)
    label = models.CharField(_('Label'), max_length=150, null=False, blank=False)
    value = models.CharField(_('Value'), max_length=150, null=False, blank=False)

Thanks for posting this. It was really helpful. Just a note: I see a little issue here: (maybe it is intentional. you can clarify)
In my case initials should be shown only when there are no Details Obj linked. Once you save your linked Details. If you reopen the changeForm, you will have duplicated Details (the ones already saved and the new initials) I added an extra check to put before line 11 of your script

if obj:
    saved = Details.objects.filter(employee=obj.id)
    if not saved:

this avoids suggesting related objects when already exist some.
Hope this helps someone :)

Thank you @LowerDeez & @serguitus, I ended up with replacing line 10 with if request.method == "GET" and (not obj or not obj.id): and it worked like a charm :)

PS - Also, didn't require to mention formset (line 5) explicitly in my case (since all custom changes needed were just the addition of initial data)