fix: add unit tests for the flatten utility function

api/src/chat/services/conversation.service.ts

@@ -181,7 +181,7 @@ export class ConversationService extends BaseService<
           context: profile.context,
         },
         {
-          flatten: true,
+          shouldFlatten: true,
         },
       );
 

api/src/utils/generics/base-repository.ts

@@ -34,6 +34,7 @@ import {
   TQueryOptions,
 } from '@/utils/types/filter.types';
 
+import { flatten } from '../helpers/flatten';
 import { PageQueryDto, QuerySortDto } from '../pagination/pagination-query.dto';
 import { DtoAction, DtoConfig, DtoInfer } from '../types/dto.types';
 
@@ -99,24 +100,6 @@ export abstract class BaseRepository<
     this.registerLifeCycleHooks();
   }
 
-  private flatten(obj: object, prefix: string = '', result: object = {}) {
-    for (const [key, value] of Object.entries(obj)) {
-      const path = prefix ? `${prefix}.${key}` : key;
-
-      if (
-        typeof value === 'object' &&
-        value !== null &&
-        !Array.isArray(value)
-      ) {
-        this.flatten(value, path, result);
-      } else {
-        result[path] = value;
-      }
-    }
-
-    return result;
-  }
-
   canPopulate(populate: string[]): boolean {
     return populate.some((p) => this.populate.includes(p as P));
   }
@@ -518,7 +501,7 @@ export abstract class BaseRepository<
     dto: UpdateQuery<DtoInfer<DtoAction.Update, Dto, D>>,
     options?: TQueryOptions<D>,
   ): Promise<T> {
-    const { flatten, ...rest } = {
+    const { shouldFlatten, ...rest } = {
       new: true,
       ...options,
     };
@@ -527,7 +510,7 @@ export abstract class BaseRepository<
         ...(typeof criteria === 'string' ? { _id: criteria } : criteria),
       },
       {
-        $set: flatten ? this.flatten(dto) : dto,
+        $set: shouldFlatten ? flatten(dto) : dto,
       },
       rest,
     );
@@ -567,7 +550,7 @@ export abstract class BaseRepository<
     options?: TFlattenOption,
   ): Promise<UpdateWriteOpResult> {
     return await this.model.updateMany<T>(filter, {
-      $set: options?.flatten ? this.flatten(dto) : dto,
+      $set: options?.shouldFlatten ? flatten(dto) : dto,
     });
   }
 

api/src/utils/helpers/flatten.spec.ts

@@ -0,0 +1,95 @@
+/*
+ * Copyright © 2025 Hexastack. All rights reserved.
+ *
+ * Licensed under the GNU Affero General Public License v3.0 (AGPLv3) with the following additional terms:
+ * 1. The name "Hexabot" is a trademark of Hexastack. You may not use this name in derivative works without express written permission.
+ * 2. All derivative works must include clear attribution to the original creator and software, Hexastack and Hexabot, in a prominent location (e.g., in the software's "About" section, documentation, and README file).
+ */
+
+import { flatten } from './flatten';
+
+describe('flatten', () => {
+  it('should support a nested object with one nested level', () => {
+    const object = {
+      name: 'name',
+      context: { nestedField: 'value' },
+    };
+    const result = flatten(object);
+
+    expect(result).toStrictEqual({
+      name: 'name',
+      'context.nestedField': 'value',
+    });
+  });
+
+  it('should support a nested object with multiple nested levels', () => {
+    const object = {
+      name: 'name',
+      context: {
+        nestedField: 'value',
+        country: {
+          isoCode: 'usa',
+          phonePrefix: '+1',
+          countryName: 'United States',
+        },
+      },
+    };
+    const result = flatten(object);
+
+    expect(result).toStrictEqual({
+      name: 'name',
+      'context.nestedField': 'value',
+      'context.country.isoCode': 'usa',
+      'context.country.phonePrefix': '+1',
+      'context.country.countryName': 'United States',
+    });
+  });
+
+  it('should support custom prefix', () => {
+    const object = {
+      isoCode: 'tun',
+      phonePrefix: '+216',
+      countryName: 'Tunisia',
+    };
+    const result = flatten(object, 'context.country');
+
+    expect(result).toStrictEqual({
+      'context.country.isoCode': 'tun',
+      'context.country.phonePrefix': '+216',
+      'context.country.countryName': 'Tunisia',
+    });
+  });
+
+  it('should support custom static initial value', () => {
+    const object = {
+      context: {
+        country: { isoCode: 'fra', phonePrefix: '+33', countryName: 'France' },
+      },
+    };
+    const result = flatten(object, undefined, { language: 'fr' });
+
+    expect(result).toStrictEqual({
+      language: 'fr',
+      'context.country.isoCode': 'fra',
+      'context.country.phonePrefix': '+33',
+      'context.country.countryName': 'France',
+    });
+  });
+
+  it('should support an object without nested object', () => {
+    const object = {
+      name: 'name',
+    };
+    const result = flatten(object);
+
+    expect(result).toStrictEqual({
+      name: 'name',
+    });
+  });
+
+  it('should support an empty object', () => {
+    const result = flatten({});
+
+    expect(result).toStrictEqual({});
+  });
+});

api/src/utils/helpers/flatten.ts

@@ -0,0 +1,32 @@
+/*
+ * Copyright © 2025 Hexastack. All rights reserved.
+ *
+ * Licensed under the GNU Affero General Public License v3.0 (AGPLv3) with the following additional terms:
+ * 1. The name "Hexabot" is a trademark of Hexastack. You may not use this name in derivative works without express written permission.
+ * 2. All derivative works must include clear attribution to the original creator and software, Hexastack and Hexabot, in a prominent location (e.g., in the software's "About" section, documentation, and README file).
+ */
+
+/**
+ * Flattens a nested object into a single-level object with dot-separated keys.
+ * @param data - The data object to flatten
+ * @param prefix - The optional base key to prefix to the current object's keys
+ * @param result - The optional accumulator for the flattened object  data
+ * @returns A new object with flattened keys
+ */
+export const flatten = (
+  data: object,
+  prefix: string | undefined = undefined,
+  result: object = {},
+) => {
+  for (const [key, value] of Object.entries(data)) {
+    const path = prefix ? `${prefix}.${key}` : key;
+
+    if (typeof value === 'object' && value !== null && !Array.isArray(value)) {
+      flatten(value, path, result);
+    } else {
+      result[path] = value;
+    }
+  }
+
+  return result;
+};

api/src/utils/types/filter.types.ts

@@ -143,6 +143,6 @@ export type TFilterQuery<T, S = TReplaceId<T>> = (
 
 export type THydratedDocument<T> = TOmitId<HydratedDocument<T>>;
 
-export type TFlattenOption = { flatten?: boolean };
+export type TFlattenOption = { shouldFlatten?: boolean };
 
 export type TQueryOptions<D> = (QueryOptions<D> & TFlattenOption) | null;