fix: make filter work on count for consistency

packages/filter/src/query.ts

@@ -247,6 +247,14 @@ export type FilterExcludingWhere<MT extends object = AnyObject> = Omit<
   'where'
 >;
 
+/**
+ * Filter without additional properties for count
+ */
+export type FilterExcludingsForCount<MT extends object = AnyObject> = Omit<
+  Filter<MT>,
+  'fields' | 'order' | 'limit' | 'skip' | 'offset' | 'include'
+>;
+
 /**
  * TypeGuard for Filter
  * @param candidate

packages/rest-crud/src/__tests__/acceptance/default-model-crud-rest.acceptance.ts

@@ -154,6 +154,14 @@ describe('CrudRestController for a simple Product model', () => {
         .expect(200);
       expect(body).to.deepEqual({count: 1 /* pencil was omitted */});
     });
+
+    it('supports `filter` query param', async () => {
+      const {body} = await client
+        .get('/products/count')
+        .query({'filter[where][name]': pen.name})
+        .expect(200);
+      expect(body).to.deepEqual({count: 1 /* pencil was omitted */});
+    });
   });
 
   describe('updateAll', () => {

packages/rest-crud/src/crud-rest.controller.ts

@@ -10,6 +10,7 @@ import {
   Entity,
   EntityCrudRepository,
   Filter,
+  FilterExcludingsForCount,
   FilterExcludingWhere,
   Where,
 } from '@loopback/repository';
@@ -189,8 +190,15 @@ export function defineCrudRestController<
     async count(
       @param.where(modelCtor)
       where?: Where<T>,
+      @param.query.object(
+        'filter',
+        getFilterSchemaFor(modelCtor, {
+          exclude: ['fields', 'order', 'limit', 'skip', 'offset', 'include'],
+        }),
+      )
+      filter?: FilterExcludingsForCount<T>,
     ): Promise<Count> {
-      return this.repository.count(where);
+      return this.repository.count(where || filter?.where);
     }
   }