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docs/edit_multiple_models.rst

@@ -11,7 +11,7 @@ You have the :code:`Category` model, and you need to add and edit :code:`Villain
 
     @admin.register(Category)
     class CategoryAdmin(admin.ModelAdmin):
-        ..
+        ...
 
         inlines = [VillainInline]
 

docs/filter_fk_dropdown.rst

@@ -1,2 +1,16 @@
 How to filter FK dropdown values in django admin?
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+Your :code:`Hero` model has a FK to :code:`Category`.
+So all category objects will show in the admin dropdown for category. If instead, you wanted to see only a subset,
+Django allows you to customize that by overriding :code:`formfield_for_foreignkey`::
+
+    @admin.register(Hero)
+    class HeroAdmin(admin.ModelAdmin, ExportCsvMixin):
+        ...
+        def formfield_for_foreignkey(self, db_field, request, **kwargs):
+            if db_field.name == "category":
+                kwargs["queryset"] = Category.objects.filter(name__in=['God', 'Demi God'])
+            return super().formfield_for_foreignkey(db_field, request, **kwargs)
+
+.. image:: filter_fk_dropdown.png

docs/many_fks.rst

@@ -1,2 +1,26 @@
 How to manage a model with a FK with a large number of objects?
 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+You can create a large number of categories like this::
+
+    categories = [Category(**{"name": "cat-{}".format(i)}) for i in range(100000)]
+    Category.objects.bulk_create(categories)
+
+
+Now as :code:`Category` has more than 100000 objects, when you go to the :code:`Hero` admin, it will have category dropdown with 100000 selections.
+This will make the page both slow and the dropdown hard to use.
+
+You can change how admin hand;es it by setting the :code:`raw_id_fields`::
+
+    @admin.register(Hero)
+    class HeroAdmin(admin.ModelAdmin, ExportCsvMixin):
+        ...
+        raw_id_fields = ["category"]
+
+This change the Hero admin to look like:
+
+.. image:: raw_id_fields_1.png
+
+Add the popup looks like this
+
+.. image:: raw_id_fields_2.png

docs/single_admin_multiple_models.rst

@@ -1,2 +1,31 @@
 How to create a single Django admin from two different models?
 =================================================================
+
+
+:code:`Hero` has a FK to :code:`Category`, so you can select a category from Hero admin.
+If you want to also be able to create :code:`Category` objects from Hero admin, you can change the form for Hero admin, and customise the
+:code:`save_model` behaviour.::
+
+    class HeroForm(forms.ModelForm):
+        category_name = forms.CharField()
+
+        class Meta:
+            model = Hero
+            exclude = ["category"]
+
+
+    @admin.register(Hero)
+    class HeroAdmin(admin.ModelAdmin, ExportCsvMixin):
+        form = HeroForm
+        ....
+
+        def save_model(self, request, obj, form, change):
+            category_name = form.cleaned_data["category_name"]
+            category, _ = Category.objects.get_or_create(name=category_name)
+            obj.category = category
+            super().save_model(request, obj, form, change)
+
+
+With this change, your admin looks like below and has allows creating or updating category from the Hero admin.
+
+.. image:: single_admin_multiple_model.png

heroes_and_monsters/entities/admin.py

@@ -1,5 +1,6 @@
 from django.contrib import admin
 from django.db.models import Count
+from django import forms
 
 from .models import Hero, Villain, Category, Origin, HeroProxy, AllEntity, HeroAcquaintance
 
@@ -53,14 +54,24 @@ def export_as_csv(self, request, queryset):
 class HeroAcquaintanceInline(admin.TabularInline):
     model = HeroAcquaintance
 
+class HeroForm(forms.ModelForm):
+    category_name = forms.CharField()
+
+    class Meta:
+        model = Hero
+        exclude = ["category"]
+
 
 @admin.register(Hero)
 class HeroAdmin(admin.ModelAdmin, ExportCsvMixin):
+    # form = HeroForm
+
     list_display = ("name", "is_immortal", "category", "origin", "is_very_benevolent", "children_display")
     list_filter = ("is_immortal", "category", "origin", IsVeryBenevolentFilter)
     actions = ["mark_immortal"]
     date_hierarchy = 'added_on'
     inlines = [HeroAcquaintanceInline]
+    raw_id_fields = ["category"]
 
     exclude = ['added_by',]
 
@@ -98,6 +109,9 @@ def children_display(self, obj):
     #     else:
     #         return []
 
+    def formfield_for_foreignkey(self, db_field, request, **kwargs):
+        return super().formfield_for_foreignkey(db_field, request, **kwargs)
+
     def get_urls(self):
         urls = super().get_urls()
         my_urls = [
@@ -117,9 +131,12 @@ def set_mortal(self, request):
         return HttpResponseRedirect("../")
 
     def save_model(self, request, obj, form, change):
+        category_name = form.cleaned_data["category_name"]
         if not obj.pk:
             # Only set added_by during the first save.
             obj.added_by = request.user
+        category, _ = Category.objects.get_or_create(name=category_name)
+        obj.category = category
         super().save_model(request, obj, form, change)