fix(datasource-mongoose): don't return records for null values of fla…

…ttened fields when using asModel on object fields (#853)

packages/datasource-mongoose/src/collection.ts

@@ -25,6 +25,7 @@ import {
   splitId,
   unflattenRecord,
 } from './utils/helpers';
+import AsModelNotNullGenerator from './utils/pipeline/as-model-not-null';
 import FilterGenerator from './utils/pipeline/filter';
 import GroupGenerator from './utils/pipeline/group';
 import LookupGenerator from './utils/pipeline/lookup';
@@ -54,13 +55,26 @@ export default class MongooseCollection extends BaseCollection {
     caller: Caller,
     filter: PaginatedFilter,
     projection: Projection,
+  ): Promise<RecordData[]> {
+    return this._list(
+      AsModelNotNullGenerator.asModelNotNull(this.model, this.stack),
+      filter,
+      projection,
+    );
+  }
+
+  private async _list(
+    pipelineBefore: PipelineStage[],
+    filter: PaginatedFilter,
+    projection: Projection,
   ): Promise<RecordData[]> {
     const lookupProjection = projection.union(
       filter.conditionTree?.projection,
       filter.sort?.projection,
     );
 
     const records = await this.model.aggregate([
+      ...(pipelineBefore || []),
       ...this.buildBasePipeline(filter, lookupProjection),
       ...ProjectionGenerator.project(projection),
     ]);
@@ -194,7 +208,7 @@ export default class MongooseCollection extends BaseCollection {
     // Fetch the ids of the documents OR subdocuments that will be updated.
     // We need to do that regardless of `this.prefix` because the filter may contain conditions on
     // relationships.
-    const records = await this.list(caller, filter, new Projection('_id'));
+    const records = await this._list([], filter, new Projection('_id'));
     const ids = records.map(record => record._id);
 
     if (this.stack.length < 2) {
@@ -242,7 +256,7 @@ export default class MongooseCollection extends BaseCollection {
   }
 
   private async _delete(caller: Caller, filter: Filter): Promise<void> {
-    const records = await this.list(caller, filter, new Projection('_id'));
+    const records = await this._list([], filter, new Projection('_id'));
     const ids = records.map(record => record._id);
 
     if (this.stack.length < 2) {

packages/datasource-mongoose/src/utils/pipeline/as-model-not-null.ts

@@ -0,0 +1,24 @@
+import { Model, PipelineStage } from 'mongoose';
+
+/**
+ * Generate pipeline to query submodels.
+ *
+ * The operations make rotations in the documents so that the root is changed to the submodel
+ * without loosing the parent (which may be needed later on).
+ */
+export default class AsModelNotNullGenerator {
+  static asModelNotNull(
+    model: Model<unknown>,
+    stack: { prefix: string | null; asFields: string[]; asModels: string[] }[],
+  ): PipelineStage[] {
+    return stack.flatMap(({ prefix, asModels }) => {
+      return asModels.map(
+        (asModel): PipelineStage => ({
+          $match: {
+            [[prefix, asModel].filter(Boolean).join('.')]: { $ne: null },
+          },
+        }),
+      );
+    });
+  }
+}

packages/datasource-mongoose/test/integration/flattener/_build-models.ts

@@ -37,6 +37,9 @@ export default async function setupFlattener(dbName = 'test') {
       name: String,
       address: {
         street: String,
+        city: String,
+        zipCode: String,
+        number: String,
       },
     }),
   );

packages/datasource-mongoose/test/integration/flattener/collection_list.test.ts

@@ -179,6 +179,30 @@ describe('Complex flattening', () => {
           }),
         ]);
       });
+
+      it('should not retrieve records for children models when the value is null', async () => {
+        connection = await setupFlattener('collection_flattener_list');
+        const dataSource = new MongooseDatasource(connection, {
+          flattenMode: 'manual',
+          flattenOptions: {
+            companies: { asModels: ['address'] },
+          },
+        });
+
+        const [company] = await dataSource
+          .getCollection('companies')
+          .create(caller, [{ name: 'Renault' }]);
+
+        const records = await dataSource.getCollection('companies_address').list(
+          caller,
+          new Filter({
+            conditionTree: new ConditionTreeLeaf('parent:_id', 'Equal', `${company._id}`),
+          }),
+          new Projection('_id', 'horsePower', 'parentId', 'parent:_id', 'parent:address:city'),
+        );
+
+        expect(records).toEqual([]);
+      });
     });
   });
 });