like mdoel

likes/admin.py

@@ -0,0 +1,15 @@
+from django.contrib import admin
+from likes.models import Like
+
+
+@admin.register(Like)
+class LikeAdmin(admin.ModelAdmin):
+    list_display = (
+        'user',
+        'content_type',
+        'object_id',
+        'content_object',
+        'created_at',
+    )
+    list_filter = ('content_type',)
+    date_hierarchy = 'created_at'

likes/apps.py

@@ -0,0 +1,5 @@
+from django.apps import AppConfig
+
+
+class LikesConfig(AppConfig):
+    name = 'likes'

likes/models.py

@@ -0,0 +1,35 @@
+from django.contrib.auth.models import User
+from django.contrib.contenttypes.fields import GenericForeignKey
+from django.contrib.contenttypes.models import ContentType
+from django.db import models
+
+
+class Like(models.Model):
+    object_id = models.PositiveIntegerField()
+    content_type = models.ForeignKey(
+        ContentType,
+        on_delete=models.SET_NULL,
+        null=True,
+    )
+    # user liked content_object at created_at
+    content_object = GenericForeignKey('content_type', 'object_id')
+    user = models.ForeignKey(User, on_delete=models.SET_NULL, null=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        # 这里使用 unique together 也就会建一个 <user, content_type, object_id>
+        # 的索引。这个索引同时还可以具备查询某个 user like 了哪些不同的 objects 的功能
+        # 因此如果 unique together 改成 <content_type, object_id, user>
+        # 就没有这样的效果了
+        unique_together = (('user', 'content_type', 'object_id'),)
+        # 这个 index 的作用是可以按时间排序某个被 like 的 content_object 的所有 likes
+        index_together = (('content_type', 'object_id', 'created_at'),)
+
+    def __str__(self):
+        return '{} - {} liked {} {}'.format(
+            self.created_at,
+            self.user,
+            self.content_type,
+            self.object_id,
+        )
+

twitter/settings.py

@@ -49,6 +49,7 @@
     'friendships',
     'newsfeeds',
     'comments',
+    'likes',
 
 ]