chore: reusable pagination code

app/routes.py

@@ -1,5 +1,6 @@
 from flask import Blueprint, jsonify, request
 from app.models import Districts, Provinces, Regencies, Villages
+from app.utils.pagination_query import Pagination
 
 province_bp = Blueprint("provinces", __name__)
 regency_bp = Blueprint("regencies", __name__)
@@ -12,38 +13,21 @@ def get_provinces():
     show_all = request.args.get("show_all", "false").lower() == "true"
     page = request.args.get("page", 1, type=int)
     per_page = request.args.get("per_page", 10, type=int)
-
     if per_page <= 0:
         return jsonify({"error": "invalid per_page value"}), 400
-
     if show_all:
         provinces = Provinces.query.all()
-        response = [
-            {"code": province.code, "name": province.name} for province in provinces
-        ]
-    else:
-        total_provinces = Provinces.query.count()
-        total_pages = (total_provinces + per_page - 1) // per_page
-
-        if page > total_pages:
-            return jsonify({"error": "Page number exceeds total pages"}), 400
-
-        provinces_query = Provinces.query.paginate(
-            page=page, per_page=per_page, error_out=False
-        )
-
         response = {
-            "pagination": {
-                "total_items": provinces_query.total,
-                "total_pages": provinces_query.pages,
-                "current_page": provinces_query.page,
-                "per_page": provinces_query.per_page,
-            },
             "data": [
-                {"code": province.code, "name": province.name}
-                for province in provinces_query.items
-            ],
+                {"code": province.code, "name": province.name} for province in provinces
+            ]
         }
+    else:
+        try:
+            pagination = Pagination(Provinces.query, page, per_page)
+            response = pagination.get_paginated_data()
+        except ValueError as e:
+            return jsonify({"error": str(e)}), 400
     return jsonify(response)
 
 

app/utils/pagination_query.py

@@ -0,0 +1,46 @@
+class Pagination:
+    def __init__(self, query, page=1, per_page=10):
+        self.query = query
+        self.page = self._validate_page(page)
+        self.per_page = self._validate_per_page(per_page)
+
+    def _validate_page(self, page):
+        try:
+            page = int(page)
+        except ValueError:
+            raise ValueError("Page must be an integer")
+        if page < 1:
+            raise ValueError("Page number must be greater than zero")
+        return page
+
+    def _validate_per_page(self, per_page):
+        try:
+            per_page = int(per_page)
+        except ValueError:
+            raise ValueError("per_page must be an integer")
+        if per_page <= 0:
+            raise ValueError("per_page must be greater than zero")
+        return per_page
+
+    def get_paginated_data(self):
+        total_items = self.query.count()
+        total_pages = (total_items + self.per_page - 1) // self.per_page
+
+        if self.page > total_pages:
+            raise ValueError("Page number exceeds total pages")
+
+        paginated_query = self.query.paginate(
+            page=self.page, per_page=self.per_page, error_out=False
+        )
+
+        return {
+            "pagination": {
+                "total_items": paginated_query.total,
+                "total_pages": paginated_query.pages,
+                "current_page": paginated_query.page,
+                "per_page": paginated_query.per_page,
+            },
+            "data": [
+                {"code": item.code, "name": item.name} for item in paginated_query.items
+            ],
+        }