Django 1.7 removing Add button from inline form

To remove the "Add another" option, please add the below method in admin inline class.

def has_add_permission(self, request):
    return False

Similarly if you want to disable "Delete?" option, add the following method in admin inline class.

def has_delete_permission(self, request, obj=None):
    return False

After a couple of intense days, I finally managed to find a way to achieve that.

A simple trick such as this is more than enough when dealing with this problem within ModelAdmin subclasses (see ClienteAdmin in my code above), so here's the class version without adding capabilities for "Prodotto" field:

@admin.register(Cliente)
class ClienteAdmin(admin.ModelAdmin):
    list_display = [
        'ragione_sociale', 'forma_societaria', 'titolare', 'partita_iva', ]
    list_filter = ['forma_societaria', ]
    search_fields = ['ragione_sociale', ]
    inlines = [RecapitoInline, SedeInline]
    def get_form(self, request, obj=None, **kwargs):    # Just added this override
        form = super(ClienteAdmin, self).get_form(request, obj, **kwargs)
        form.base_fields['prodotto'].widget.can_add_related = False
        return form

The real pain comes when dealing with inline classes (TabularInline, StackedInline), as the get_form() function seems not to be called at all, so the previous way won't work.

Explaining all my previous attempts would take too long, and I'm probably not even good enough with Django yet to tell why they didn't work. So let's get straight to the solution, which in fact is not even that complicated.

I subclassed django.contrib.admin.widgets.RelatedFieldWidgetWrapper widget and overridden its render method, so that it doesn't append the "add-another" anchor to the output. Easily done by commenting out a few lines. After doing so, monkeypatching the original RelatedFieldWidgetWrapper with my own version (django.contrib.admin.widgets.RelatedFieldWidgetWrapper = NoAddingRelatedFieldWidgetWrapper) made the trick.

Clearly, for it to work I had to add the import line in the admin.py:

from .widgets import NoAddingRelatedFieldWidgetWrapper

widgets.py

import django.contrib.admin.widgets
from django.utils.safestring import mark_safe


class NoAddingRelatedFieldWidgetWrapper(django.contrib.admin.widgets.RelatedFieldWidgetWrapper):

    def render(self, name, value, *args, **kwargs):
        from django.contrib.admin.views.main import TO_FIELD_VAR
        rel_to = self.rel.to
        info = (rel_to._meta.app_label, rel_to._meta.model_name)
        self.widget.choices = self.choices
        output = [self.widget.render(name, value, *args, **kwargs)]
        '''
        if self.can_add_related:
            related_url = reverse('admin:%s_%s_add' % info, current_app=self.admin_site.name)
            url_params = '?%s=%s' % (TO_FIELD_VAR, self.rel.get_related_field().name)
            # TODO: "add_id_" is hard-coded here. This should instead use the
            # correct API to determine the ID dynamically.
            output.append('<a href="%s%s" class="add-another" id="add_id_%s" onclick="return showAddAnotherPopup(this);"> '
                          % (related_url, url_params, name))
            output.append('<img src="%s" width="10" height="10" alt="%s"/></a>'
                          % (static('admin/img/icon_addlink.gif'), _('Add Another')))
        '''
        return mark_safe(''.join(output))

# Monkeypatch
django.contrib.admin.widgets.RelatedFieldWidgetWrapper = NoAddingRelatedFieldWidgetWrapper

For the sake of completion, here's the final version of the related admin.py:

admin.py

from django.contrib import admin
import django.contrib.admin.widgets

from django.db import models

from .models import Cliente, Prodotto, Sede
from apps.recapito.models import RecapitoCliente
from .widgets import NoAddingRelatedFieldWidgetWrapper


class SedeInline(admin.TabularInline):
    model = Sede
    extra = 1

    def provincia(self, obj):
        return obj.comune.provincia

    readonly_fields = ['provincia', ]


class RecapitoInline(admin.TabularInline):
    model = RecapitoCliente
    extra = 1
    readonly_fields = ['cliente', 'tipo', 'recapito', ]


@admin.register(Cliente)
class ClienteAdmin(admin.ModelAdmin):
    list_display = [
        'ragione_sociale', 'forma_societaria', 'titolare', 'partita_iva', ]
    list_filter = ['forma_societaria', ]
    search_fields = ['ragione_sociale', ]
    inlines = [RecapitoInline, SedeInline]
    def get_form(self, request, obj=None, **kwargs):
        form = super(ClienteAdmin, self).get_form(request, obj, **kwargs)
        form.base_fields['prodotto'].widget.can_add_related = False
        return form

Shall anyone come out with any better solution, I'll gladly accept it in place of mine.

I think this is a less hacky solution than the one you ended up with. It worked for me, anyway.

Basically, it's the inline equivalent of what you suggested doing with the overriding the get_form method of ModelAdmin. Here we override get_formset in the inline class, get the form off the formset, and do the exact same thing. Seems to work fine, at least in 1.9, which I am using.

class VersionEntryInline(admin.TabularInline):
    template = 'admin/edit_inline/tabular_versionentry.html'
    model = VersionEntry
    extra = 0

    def get_formset(self, request, obj=None, **kwargs):
        """
        Override the formset function in order to remove the add and change buttons beside the foreign key pull-down
        menus in the inline.
        """
        formset = super(VersionEntryInline, self).get_formset(request, obj, **kwargs)
        form = formset.form
        widget = form.base_fields['project'].widget
        widget.can_add_related = False
        widget.can_change_related = False
        widget = form.base_fields['version'].widget
        widget.can_add_related = False
        widget.can_change_related = False
        return formset