Make cookbook example working on django 2 (#680)

examples/cookbook/cookbook/ingredients/models.py

@@ -11,7 +11,9 @@ class Category(models.Model):
 class Ingredient(models.Model):
     name = models.CharField(max_length=100)
     notes = models.TextField(null=True, blank=True)
-    category = models.ForeignKey(Category, related_name="ingredients")
+    category = models.ForeignKey(
+        Category, related_name="ingredients", on_delete=models.CASCADE
+    )
 
     def __str__(self):
         return self.name

examples/cookbook/cookbook/recipes/models.py

@@ -10,8 +10,10 @@ class Recipe(models.Model):
 
 
 class RecipeIngredient(models.Model):
-    recipe = models.ForeignKey(Recipe, related_name="amounts")
+    recipe = models.ForeignKey(Recipe, related_name="amounts", on_delete=models.CASCADE)
-    ingredient = models.ForeignKey(Ingredient, related_name="used_by")
+    ingredient = models.ForeignKey(
+        Ingredient, related_name="used_by", on_delete=models.CASCADE
+    )
     amount = models.FloatField()
     unit = models.CharField(
         max_length=20,

examples/cookbook/cookbook/settings.py

@@ -43,13 +43,12 @@ INSTALLED_APPS = [
     "cookbook.recipes.apps.RecipesConfig",
 ]
 
-MIDDLEWARE_CLASSES = [
+MIDDLEWARE = [
     "django.middleware.security.SecurityMiddleware",
     "django.contrib.sessions.middleware.SessionMiddleware",
     "django.middleware.common.CommonMiddleware",
     "django.middleware.csrf.CsrfViewMiddleware",
     "django.contrib.auth.middleware.AuthenticationMiddleware",
-    "django.contrib.auth.middleware.SessionAuthenticationMiddleware",
     "django.contrib.messages.middleware.MessageMiddleware",
     "django.middleware.clickjacking.XFrameOptionsMiddleware",
 ]

examples/cookbook/requirements.txt

@@ -1,5 +1,5 @@
 graphene
 graphene-django
 graphql-core>=2.1rc1
-django==1.11.21
+django==2.2.2
 django-filter>=2