fix: adjust contact balance

packages/server/src/models/Model.ts

@@ -14,13 +14,13 @@ export type PaginationQueryBuilderType<M extends Model> = QueryBuilder<
   PaginationResult<M>
 >;
 
-class PaginationQueryBuilder<M extends Model, R = M[]> extends QueryBuilder<
-  M,
-  R
-> {
+export class PaginationQueryBuilder<
+  M extends Model,
+  R = M[],
+> extends QueryBuilder<M, R> {
   pagination(page: number, pageSize: number): PaginationQueryBuilderType<M> {
     const query = super.page(page, pageSize);
-    
+
     return query.runAfter(({ results, total }) => {
       return {
         results,
@@ -34,10 +34,27 @@ class PaginationQueryBuilder<M extends Model, R = M[]> extends QueryBuilder<
   }
 }
 
+// New BaseQueryBuilder extending PaginationQueryBuilder
+export class BaseQueryBuilder<
+  M extends Model,
+  R = M[],
+> extends PaginationQueryBuilder<M, R> {
+  // You can add more shared query methods here in the future
+
+  changeAmount(whereAttributes, attribute, amount) {
+    const changeMethod = amount > 0 ? 'increment' : 'decrement';
+
+    return this.where(whereAttributes)[changeMethod](
+      attribute,
+      Math.abs(amount),
+    );
+  }
+}
+
 export class BaseModel extends Model {
   public readonly id: number;
   public readonly tableName: string;
 
-  QueryBuilderType!: PaginationQueryBuilder<this>;
-  static QueryBuilder = PaginationQueryBuilder;
+  QueryBuilderType!: BaseQueryBuilder<this>;
+  static QueryBuilder = BaseQueryBuilder;
 }