add drf_spectacular, type and serialize channel app

backend/common/serializers.py

@@ -0,0 +1,29 @@
+"""common serializers"""
+
+# pylint: disable=abstract-method
+
+from rest_framework import serializers
+
+
+class ErrorResponseSerializer(serializers.Serializer):
+    """error message"""
+
+    error = serializers.CharField()
+
+
+class PaginationSerializer(serializers.Serializer):
+    """serialize paginate response"""
+
+    page_size = serializers.IntegerField()
+    page_from = serializers.IntegerField()
+    prev_pages = serializers.ListField(
+        child=serializers.IntegerField(), allow_null=True
+    )
+    current_page = serializers.IntegerField()
+    max_hits = serializers.BooleanField()
+    params = serializers.CharField()
+    last_page = serializers.BooleanField()
+    next_pages = serializers.ListField(
+        child=serializers.IntegerField(), allow_null=True
+    )
+    total_hits = serializers.IntegerField()