Added readonly field chapter

docs/changeview_readonly.rst

@@ -1,2 +1,15 @@
 How to mark a field as readonly in admin?
 ++++++++++++++++++++++++++++++++++++++++++
+
+UMSRA has temporarily decided to stop tracking the family trees of mythological entities. You have been asked to make the :code:`father`, :code:`mother` and :code:`spouse` fields readonly.
+
+You can do this by::
+
+    @admin.register(Hero)
+    class HeroAdmin(admin.ModelAdmin, ExportCsvMixin):
+        ...
+        readonly_fields = ["father", "mother", "spouse"]
+
+Your create form looks like this:
+
+.. image::changeview_readonly.png

docs/uneditable_existing.rst

@@ -11,4 +11,4 @@ You can do this by overriding :code:`get_readonly_fields` method, like this::
         else:
             return []
 
-:code:`obj` is None during the object creation, but set to the object being edited during an edit.
+:code:`obj` is :code:`None` during the object creation, but set to the object being edited during an edit.

heroes_and_monsters/entities/admin.py

@@ -55,11 +55,13 @@ class HeroAdmin(admin.ModelAdmin, ExportCsvMixin):
 
     exclude = ['added_by',]
 
-    def get_readonly_fields(self, request, obj=None):
-        if obj:
-            return ["name", "category"]
-        else:
-            return []
+    readonly_fields = ["father", "mother", "spouse"]
+
+    # def get_readonly_fields(self, request, obj=None):
+    #     if obj:
+    #         return ["name", "category"]
+    #     else:
+    #         return []
 
     def save_model(self, request, obj, form, change):
         if not obj.pk: