.prettierrc

@@ -1,6 +0,0 @@
-{
-  "singleQuote": true,
-  "trailingComma": "none",
-  "printWidth": 160,
-  "bracketSameLine": true
-}

bruno/Common Cents/Categories/LOC DELETE Category.bru

@@ -0,0 +1,15 @@
+meta {
+  name: LOC DELETE Category
+  type: http
+  seq: 5
+}
+
+delete {
+  url: {{localBaseUrl}}/{{resourcePath}}/{{resourceId}}
+  body: none
+  auth: inherit
+}
+
+vars:pre-request {
+  resourceId: cbf30070-9ff7-419f-a567-f7d145be445b
+}

bruno/Common Cents/Categories/LOC GET Categories.bru

@@ -0,0 +1,11 @@
+meta {
+  name: LOC GET Categories
+  type: http
+  seq: 1
+}
+
+get {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: none
+  auth: inherit
+}

bruno/Common Cents/Categories/LOC GET Category By ID.bru

@@ -0,0 +1,15 @@
+meta {
+  name: LOC GET Category By ID
+  type: http
+  seq: 2
+}
+
+get {
+  url: {{localBaseUrl}}/{{resourcePath}}/{{resourceId}}
+  body: none
+  auth: inherit
+}
+
+vars:pre-request {
+  resourceId: 1d6d2842-b271-489b-bd93-e3ceaee5a139
+}

bruno/Common Cents/Categories/LOC POST Category.bru

@@ -0,0 +1,17 @@
+meta {
+  name: LOC POST Category
+  type: http
+  seq: 3
+}
+
+post {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: json
+  auth: inherit
+}
+
+body:json {
+  {
+    "name": "Category Three"
+  }
+}

bruno/Common Cents/Categories/LOC PUT Category.bru

@@ -0,0 +1,18 @@
+meta {
+  name: LOC PUT Category
+  type: http
+  seq: 4
+}
+
+put {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: json
+  auth: inherit
+}
+
+body:json {
+  {
+    "id": "1d6d2842-b271-489b-bd93-e3ceaee5a139",
+    "name": "Merchant One"
+  }
+}

bruno/Common Cents/Categories/folder.bru

@@ -0,0 +1,11 @@
+meta {
+  name: Categories
+}
+
+auth {
+  mode: inherit
+}
+
+vars:pre-request {
+  resourcePath: categories
+}

bruno/Common Cents/Expenses/folder.bru

@@ -1,3 +1,4 @@
 meta {
   name: Expenses
+  seq: 2
 }

bruno/Common Cents/Merchants/LOC DELETE Merchant.bru

@@ -0,0 +1,15 @@
+meta {
+  name: LOC DELETE Merchant
+  type: http
+  seq: 5
+}
+
+delete {
+  url: {{localBaseUrl}}/{{resourcePath}}/{{resourceId}}
+  body: none
+  auth: inherit
+}
+
+vars:pre-request {
+  resourceId: cbf30070-9ff7-419f-a567-f7d145be445b
+}

bruno/Common Cents/Merchants/LOC GET Merchant By ID.bru

@@ -0,0 +1,15 @@
+meta {
+  name: LOC GET Merchant By ID
+  type: http
+  seq: 2
+}
+
+get {
+  url: {{localBaseUrl}}/{{resourcePath}}/{{resourceId}}
+  body: none
+  auth: inherit
+}
+
+vars:pre-request {
+  resourceId: 1d6d2842-b271-489b-bd93-e3ceaee5a139
+}

bruno/Common Cents/Merchants/LOC GET Merchants.bru

@@ -0,0 +1,11 @@
+meta {
+  name: LOC GET Merchants
+  type: http
+  seq: 1
+}
+
+get {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: none
+  auth: inherit
+}

bruno/Common Cents/Merchants/LOC POST Merchant.bru

@@ -0,0 +1,17 @@
+meta {
+  name: LOC POST Merchant
+  type: http
+  seq: 3
+}
+
+post {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: json
+  auth: inherit
+}
+
+body:json {
+  {
+    "name": "Merchant Three"
+  }
+}

bruno/Common Cents/Merchants/LOC PUT Merchant.bru

@@ -0,0 +1,18 @@
+meta {
+  name: LOC PUT Merchant
+  type: http
+  seq: 4
+}
+
+put {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: json
+  auth: inherit
+}
+
+body:json {
+  {
+    "id": "1d6d2842-b271-489b-bd93-e3ceaee5a139",
+    "name": "Merchant One"
+  }
+}

bruno/Common Cents/Merchants/folder.bru

@@ -0,0 +1,11 @@
+meta {
+  name: Merchants
+}
+
+auth {
+  mode: inherit
+}
+
+vars:pre-request {
+  resourcePath: merchants
+}

bruno/Common Cents/Sub-categories/LOC DELETE Sub-category.bru

@@ -0,0 +1,15 @@
+meta {
+  name: LOC DELETE Sub-category
+  type: http
+  seq: 5
+}
+
+delete {
+  url: {{localBaseUrl}}/{{resourcePath}}/{{resourceId}}
+  body: none
+  auth: inherit
+}
+
+vars:pre-request {
+  resourceId: cbf30070-9ff7-419f-a567-f7d145be445b
+}

bruno/Common Cents/Sub-categories/LOC GET Sub-categories.bru

@@ -0,0 +1,11 @@
+meta {
+  name: LOC GET Sub-categories
+  type: http
+  seq: 1
+}
+
+get {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: none
+  auth: inherit
+}

bruno/Common Cents/Sub-categories/LOC GET Sub-category By ID.bru

@@ -0,0 +1,15 @@
+meta {
+  name: LOC GET Sub-category By ID
+  type: http
+  seq: 2
+}
+
+get {
+  url: {{localBaseUrl}}/{{resourcePath}}/{{resourceId}}
+  body: none
+  auth: inherit
+}
+
+vars:pre-request {
+  resourceId: 1d6d2842-b271-489b-bd93-e3ceaee5a139
+}

bruno/Common Cents/Sub-categories/LOC POST Sub-category.bru

@@ -0,0 +1,17 @@
+meta {
+  name: LOC POST Sub-category
+  type: http
+  seq: 3
+}
+
+post {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: json
+  auth: inherit
+}
+
+body:json {
+  {
+    "name": "Sub-category Three"
+  }
+}

bruno/Common Cents/Sub-categories/LOC PUT Sub-category.bru

@@ -0,0 +1,18 @@
+meta {
+  name: LOC PUT Sub-category
+  type: http
+  seq: 4
+}
+
+put {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: json
+  auth: inherit
+}
+
+body:json {
+  {
+    "id": "1d6d2842-b271-489b-bd93-e3ceaee5a139",
+    "name": "Merchant One"
+  }
+}

bruno/Common Cents/Sub-categories/folder.bru

@@ -0,0 +1,11 @@
+meta {
+  name: Sub-categories
+}
+
+auth {
+  mode: inherit
+}
+
+vars:pre-request {
+  resourcePath: sub-categories
+}

bruno/Common Cents/Tags/LOC DELETE Tag.bru

@@ -0,0 +1,15 @@
+meta {
+  name: LOC DELETE Tag
+  type: http
+  seq: 5
+}
+
+delete {
+  url: {{localBaseUrl}}/{{resourcePath}}/{{resourceId}}
+  body: none
+  auth: inherit
+}
+
+vars:pre-request {
+  resourceId: cbf30070-9ff7-419f-a567-f7d145be445b
+}

bruno/Common Cents/Tags/LOC GET Tag By ID.bru

@@ -0,0 +1,15 @@
+meta {
+  name: LOC GET Tag By ID
+  type: http
+  seq: 2
+}
+
+get {
+  url: {{localBaseUrl}}/{{resourcePath}}/{{resourceId}}
+  body: none
+  auth: inherit
+}
+
+vars:pre-request {
+  resourceId: 1d6d2842-b271-489b-bd93-e3ceaee5a139
+}

bruno/Common Cents/Tags/LOC GET Tags.bru

@@ -0,0 +1,11 @@
+meta {
+  name: LOC GET Tags
+  type: http
+  seq: 1
+}
+
+get {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: none
+  auth: inherit
+}

bruno/Common Cents/Tags/LOC POST Tag.bru

@@ -0,0 +1,17 @@
+meta {
+  name: LOC POST Tag
+  type: http
+  seq: 3
+}
+
+post {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: json
+  auth: inherit
+}
+
+body:json {
+  {
+    "name": "Tag Three"
+  }
+}

bruno/Common Cents/Tags/LOC PUT Tag.bru

@@ -0,0 +1,18 @@
+meta {
+  name: LOC PUT Tag
+  type: http
+  seq: 4
+}
+
+put {
+  url: {{localBaseUrl}}/{{resourcePath}}
+  body: json
+  auth: inherit
+}
+
+body:json {
+  {
+    "id": "1d6d2842-b271-489b-bd93-e3ceaee5a139",
+    "name": "Merchant One"
+  }
+}

bruno/Common Cents/Tags/folder.bru

@@ -0,0 +1,11 @@
+meta {
+  name: Tags
+}
+
+auth {
+  mode: inherit
+}
+
+vars:pre-request {
+  resourcePath: tags
+}

eslint.config.mjs

@@ -1,6 +1,5 @@
 // @ts-check
 import eslint from '@eslint/js';
-import eslintPluginPrettierRecommended from 'eslint-plugin-prettier/recommended';
 import globals from 'globals';
 import tseslint from 'typescript-eslint';
 
@@ -10,7 +9,6 @@ export default tseslint.config(
   },
   eslint.configs.recommended,
   ...tseslint.configs.recommendedTypeChecked,
-  eslintPluginPrettierRecommended,
   {
     languageOptions: {
       globals: {
@@ -21,15 +19,14 @@ export default tseslint.config(
       parserOptions: {
         projectService: true,
         tsconfigRootDir: import.meta.dirname,
-      },
-    },
+      }
+    }
   },
   {
     rules: {
       '@typescript-eslint/no-explicit-any': 'off',
       '@typescript-eslint/no-floating-promises': 'warn',
-      '@typescript-eslint/no-unsafe-argument': 'warn',
-      "prettier/prettier": ["error", { endOfLine: "auto" }],
-    },
-  },
+      '@typescript-eslint/no-unsafe-argument': 'warn'
+    }
+  }
 );

package.json

@@ -24,8 +24,11 @@
     "@nestjs/core": "^11.0.1",
     "@nestjs/mapped-types": "*",
     "@nestjs/platform-express": "^11.0.1",
+    "@nestjs/typeorm": "^11.0.0",
     "reflect-metadata": "^0.2.2",
-    "rxjs": "^7.8.1"
+    "rxjs": "^7.8.1",
+    "sqlite3": "^5.1.7",
+    "typeorm": "^0.3.28"
   },
   "devDependencies": {
     "@eslint/eslintrc": "^3.2.0",
@@ -42,7 +45,6 @@
     "eslint-plugin-prettier": "^5.2.2",
     "globals": "^16.0.0",
     "jest": "^30.0.0",
-    "prettier": "^3.4.2",
     "source-map-support": "^0.5.21",
     "supertest": "^7.0.0",
     "ts-jest": "^29.2.5",

src/app.controller.spec.ts

@@ -1,22 +0,0 @@
-// import { Test, TestingModule } from '@nestjs/testing';
-// import { AppController } from './app.controller';
-// import { AppService } from './app.service';
-//
-// describe('AppController', () => {
-//   let appController: AppController;
-//
-//   beforeEach(async () => {
-//     const app: TestingModule = await Test.createTestingModule({
-//       controllers: [AppController],
-//       providers: [AppService],
-//     }).compile();
-//
-//     appController = app.get<AppController>(AppController);
-//   });
-//
-//   describe('root', () => {
-//     it('should return "Hello World!"', () => {
-//       expect(appController.getHello()).toBe('Hello World!');
-//     });
-//   });
-// });

src/app.module.ts

@@ -1,11 +1,31 @@
 import { Module } from '@nestjs/common';
 import { AppController } from './app.controller';
-import { ExpensesService } from './services/expenses.service';
-import { ExpensesController } from './controllers/expenses/expenses.controller';
+import { TypeOrmModule, TypeOrmModuleOptions } from '@nestjs/typeorm';
+import { MerchantsModule } from './merchants/merchants.module';
+import { Merchant } from './merchants/entities/merchant.entity';
+import { TagsModule } from './tags/tags.module';
+import { Tag } from './tags/entities/tag.entity';
+import { CategoriesModule } from './categories/categories.module';
+import { Category } from './categories/entities/category.entity';
+import { SubCategoriesModule } from './sub-categories/sub-categories.module';
+import { SubCategory } from './sub-categories/entities/sub-category.entity';
+
+const sqliteConfig: TypeOrmModuleOptions = {
+  synchronize: true, // typeorm -h (schema:sync)
+  type: 'sqlite',
+  database: 'common-cents.db',
+  entities: [Merchant, Tag, Category, SubCategory]
+}
 
 @Module({
-  imports: [],
-  controllers: [AppController, ExpensesController],
-  providers: [ExpensesService]
+  imports: [
+    TypeOrmModule.forRoot(sqliteConfig),
+    MerchantsModule,
+    TagsModule,
+    CategoriesModule,
+    SubCategoriesModule
+  ],
+  controllers: [AppController],
+  providers: []
 })
 export class AppModule { }

src/categories/categories.controller.ts

@@ -0,0 +1,75 @@
+import {
+  Controller,
+  Get,
+  Post,
+  Put,
+  Delete,
+  Body,
+  Param,
+  HttpCode,
+  HttpStatus,
+  BadRequestException,
+  NotFoundException,
+  InternalServerErrorException
+} from '@nestjs/common';
+import { CategoriesService } from './categories.service';
+import { CreateCategoryDto } from './dto/create-category.dto';
+import { UpdateCategoryDto } from './dto/update-category.dto';
+import { Category } from './entities/category.entity';
+
+@Controller('categories')
+export class CategoriesController {
+  constructor(private readonly categoriesService: CategoriesService) { }
+
+  @Get()
+  @HttpCode(HttpStatus.OK)
+  public async findAll(): Promise<Category[]> {
+    return await this.categoriesService.findAll();
+  }
+
+  @Get(':id')
+  @HttpCode(HttpStatus.OK)
+  public async findOne(@Param('id') id: string): Promise<Category> {
+    if (!id) {
+      throw new BadRequestException('No ID provided.');
+    }
+
+    try {
+      return await this.categoriesService.findById(id);
+    }
+    catch (error) {
+      throw new NotFoundException(error);
+    }
+  }
+
+  @Post()
+  @HttpCode(HttpStatus.CREATED)
+  public async create(@Body() category: CreateCategoryDto): Promise<Category> {
+    if (!category.name) {
+      throw new BadRequestException('Category name cannot be empty.');
+    }
+
+    try {
+      return await this.categoriesService.create(category);
+    }
+    catch (error) {
+      throw new InternalServerErrorException(error);
+    }
+  }
+
+  @Put()
+  @HttpCode(HttpStatus.OK)
+  public async update(@Body() category: UpdateCategoryDto): Promise<Category> {
+    if (!category.id) {
+      throw new BadRequestException('Category ID cannot be empty.');
+    }
+
+    return await this.categoriesService.update(category);
+  }
+
+  @Delete(':id')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  public async remove(@Param('id') id: string): Promise<void> {
+    return await this.categoriesService.remove(id);
+  }
+}

src/categories/categories.module.ts

@@ -0,0 +1,10 @@
+import { Module } from '@nestjs/common';
+import { CategoriesService } from './categories.service';
+import { CategoriesController } from './categories.controller';
+import { CategoryDataService } from './category-data.service';
+
+@Module({
+  controllers: [CategoriesController],
+  providers: [CategoriesService, CategoryDataService]
+})
+export class CategoriesModule { }

src/categories/categories.service.ts

@@ -0,0 +1,35 @@
+import { Injectable } from '@nestjs/common';
+import { CreateCategoryDto } from './dto/create-category.dto';
+import { UpdateCategoryDto } from './dto/update-category.dto';
+import { CategoryDataService } from './category-data.service';
+import { Category } from './entities/category.entity';
+
+@Injectable()
+export class CategoriesService {
+  public constructor(private categoryDataService: CategoryDataService) { }
+
+  public async findAll(): Promise<Category[]> {
+    return await this.categoryDataService.getAll();
+  }
+
+  public async findById(id: string): Promise<Category> {
+    const category = await this.categoryDataService.getById(id);
+    if (!category) {
+      throw new Error('No category found');
+    }
+
+    return category;
+  }
+
+  public async create(category: CreateCategoryDto): Promise<Category> {
+    return await this.categoryDataService.create(category.name);
+  }
+
+  public async update(category: UpdateCategoryDto): Promise<Category> {
+    return await this.categoryDataService.update(category);
+  }
+
+  public async remove(id: string): Promise<void> {
+    await this.categoryDataService.delete(id);
+  }
+}

src/categories/category-data.service.ts

@@ -0,0 +1,33 @@
+import { Injectable } from '@nestjs/common';
+import { DataSource, Repository } from 'typeorm';
+import { Category } from './entities/category.entity';
+import { UpdateCategoryDto } from './dto/update-category.dto';
+
+@Injectable()
+export class CategoryDataService {
+  private categories: Repository<Category>;
+
+  public constructor(private dataSource: DataSource) {
+    this.categories = this.dataSource.getRepository(Category);
+  }
+
+  public async getAll(): Promise<Category[]> {
+    return await this.categories.find();
+  }
+
+  public async getById(id: string): Promise<Category | null> {
+    return await this.categories.findOneBy({ id });
+  }
+
+  public async create(name: string): Promise<Category> {
+    return await this.categories.save({ name });
+  }
+
+  public async update(category: UpdateCategoryDto): Promise<Category> {
+    return await this.categories.save(category);
+  }
+
+  public async delete(id: string): Promise<void> {
+    await this.categories.delete({ id });
+  }
+}

src/categories/dto/create-category.dto.ts

@@ -0,0 +1,3 @@
+export class CreateCategoryDto {
+  name: string;
+}

src/categories/dto/update-category.dto.ts

@@ -0,0 +1,4 @@
+export class UpdateCategoryDto {
+  id: string;
+  name: string;
+}

src/categories/entities/category.entity.ts

@@ -0,0 +1,10 @@
+import { Column, Entity, PrimaryGeneratedColumn } from 'typeorm';
+
+@Entity()
+export class Category {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column()
+  name: string;
+}

src/controllers/expenses/expense.dto.ts

@@ -1,24 +0,0 @@
-import { PartialType } from '@nestjs/mapped-types';
-
-export class CreateExpenseDto {
-  date: Date;
-  cents: number;
-  categoryId: string;
-  merchantId?: string;
-  subcategoryIds?: string[];
-  tagIds?: string[];
-  description?: string;
-}
-
-export class UpdateExpenseDto extends PartialType(CreateExpenseDto) {}
-
-export class GetExpenseDto {
-  id: string;
-  date: Date;
-  cents: number;
-  category: string;
-  merchant?: string;
-  subcategories?: string[];
-  tags?: string[];
-  description?: string;
-}

src/controllers/expenses/expense.entities.ts

@@ -1,30 +0,0 @@
-export class Expense {
-  id: string;
-  date: Date;
-  cents: number;
-  categoryId: string;
-  merchantId?: string;
-  subcategoryIds: string[];
-  tagIds: string[];
-  description?: string;
-}
-
-export class Category {
-  id: string;
-  category: string;
-}
-
-export class SubCategory {
-  id: string;
-  subcategory: string;
-}
-
-export class Merchant {
-  id: string;
-  merchant: string;
-}
-
-export class Tag {
-  id: string;
-  tag: string;
-}

src/controllers/expenses/expenses.controller.ts

@@ -1,44 +0,0 @@
-import { Controller, Get, Post, Body, Patch, Param, Delete, NotFoundException, HttpCode } from '@nestjs/common';
-import { ExpensesService } from '../../services/expenses.service';
-import { CreateExpenseDto, UpdateExpenseDto } from './expense.dto';
-
-@Controller('expenses')
-export class ExpensesController {
-  constructor(private readonly expensesService: ExpensesService) {}
-
-  @Post()
-  create(@Body() createExpenseDto: CreateExpenseDto) {
-    return this.expensesService.create(createExpenseDto);
-  }
-
-  @Get()
-  findAll() {
-    return this.expensesService.findAll();
-  }
-
-  @Get(':id')
-  findOne(@Param('id') id: string) {
-    const expense = this.expensesService.findOne(id);
-    if (!expense) {
-      throw new NotFoundException();
-    }
-
-    return expense;
-  }
-
-  @Patch(':id')
-  update(@Param('id') id: string, @Body() updateExpenseDto: UpdateExpenseDto) {
-    const expense = this.expensesService.update(id, updateExpenseDto);
-    if (!expense) {
-      throw new NotFoundException();
-    }
-
-    return expense;
-  }
-
-  @Delete(':id')
-  @HttpCode(204)
-  remove(@Param('id') id: string) {
-    return this.expensesService.remove(id);
-  }
-}

src/merchants/dto/create-merchant.dto.ts

@@ -0,0 +1,3 @@
+export class CreateMerchantDto {
+  name: string;
+}

src/merchants/dto/update-merchant.dto.ts

@@ -0,0 +1,4 @@
+export class UpdateMerchantDto {
+  id: string;
+  name: string;
+}

src/merchants/entities/merchant.entity.ts

@@ -0,0 +1,10 @@
+import { Column, Entity, PrimaryGeneratedColumn } from 'typeorm';
+
+@Entity()
+export class Merchant {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column()
+  name: string;
+}

src/merchants/merchant-data.service.ts

@@ -0,0 +1,33 @@
+import { Injectable } from '@nestjs/common';
+import { DataSource, Repository } from 'typeorm';
+import { Merchant } from './entities/merchant.entity';
+import { UpdateMerchantDto } from './dto/update-merchant.dto';
+
+@Injectable()
+export class MerchantDataService {
+  private merchants: Repository<Merchant>;
+
+  public constructor(private dataSource: DataSource) {
+    this.merchants = this.dataSource.getRepository(Merchant);
+  }
+
+  public async getAll(): Promise<Merchant[]> {
+    return await this.merchants.find();
+  }
+
+  public async getById(id: string): Promise<Merchant | null> {
+    return await this.merchants.findOneBy({ id });
+  }
+
+  public async create(name: string): Promise<Merchant> {
+    return await this.merchants.save({ name });
+  }
+
+  public async update(merchant: UpdateMerchantDto): Promise<Merchant> {
+    return await this.merchants.save(merchant);
+  }
+
+  public async delete(id: string): Promise<void> {
+    await this.merchants.delete({ id });
+  }
+}

src/merchants/merchants.controller.ts

@@ -0,0 +1,75 @@
+import {
+  Controller,
+  Get,
+  Post,
+  Put,
+  Delete,
+  Body,
+  Param,
+  HttpCode,
+  HttpStatus,
+  NotFoundException,
+  BadRequestException,
+  InternalServerErrorException
+} from '@nestjs/common';
+import { MerchantsService } from './merchants.service';
+import { CreateMerchantDto } from './dto/create-merchant.dto';
+import { UpdateMerchantDto } from './dto/update-merchant.dto';
+import { Merchant } from './entities/merchant.entity';
+
+@Controller('merchants')
+export class MerchantsController {
+  public constructor(private readonly merchantsService: MerchantsService) { }
+
+  @Get()
+  @HttpCode(HttpStatus.OK)
+  public async findAll(): Promise<Merchant[]> {
+    return await this.merchantsService.findAll();
+  }
+
+  @Get(':id')
+  @HttpCode(HttpStatus.OK)
+  public async findOne(@Param('id') id: string): Promise<Merchant> {
+    if (!id) {
+      throw new BadRequestException('No ID provided.');
+    }
+
+    try {
+      return await this.merchantsService.findById(id);
+    }
+    catch (error) {
+      throw new NotFoundException(error);
+    }
+  }
+
+  @Post()
+  @HttpCode(HttpStatus.CREATED)
+  public async create(@Body() merchant: CreateMerchantDto): Promise<Merchant> {
+    if (!merchant.name) {
+      throw new BadRequestException('Merchant name cannot be empty.');
+    }
+
+    try {
+      return await this.merchantsService.create(merchant);
+    }
+    catch (error) {
+      throw new InternalServerErrorException(error);
+    }
+  }
+
+  @Put()
+  @HttpCode(HttpStatus.OK)
+  public async update(@Body() merchant: UpdateMerchantDto): Promise<Merchant> {
+    if (!merchant.id) {
+      throw new BadRequestException('Merchant ID cannot be empty.');
+    }
+
+    return await this.merchantsService.update(merchant);
+  }
+
+  @Delete(':id')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  public async remove(@Param('id') id: string): Promise<void> {
+    return await this.merchantsService.remove(id);
+  }
+}

src/merchants/merchants.module.ts

@@ -0,0 +1,10 @@
+import { Module } from '@nestjs/common';
+import { MerchantsService } from './merchants.service';
+import { MerchantsController } from './merchants.controller';
+import { MerchantDataService } from './merchant-data.service';
+
+@Module({
+  controllers: [MerchantsController],
+  providers: [MerchantsService, MerchantDataService]
+})
+export class MerchantsModule { }

src/merchants/merchants.service.ts

@@ -0,0 +1,35 @@
+import { Injectable } from '@nestjs/common';
+import { CreateMerchantDto } from './dto/create-merchant.dto';
+import { UpdateMerchantDto } from './dto/update-merchant.dto';
+import { MerchantDataService } from './merchant-data.service';
+import { Merchant } from './entities/merchant.entity';
+
+@Injectable()
+export class MerchantsService {
+  public constructor(private merchantDataService: MerchantDataService) { }
+
+  public async findAll(): Promise<Merchant[]> {
+    return await this.merchantDataService.getAll();
+  }
+
+  public async findById(id: string): Promise<Merchant> {
+    const merchant = await this.merchantDataService.getById(id);
+    if (!merchant) {
+      throw new Error('Merchant not found.');
+    }
+
+    return merchant;
+  }
+
+  public async create(merchant: CreateMerchantDto): Promise<Merchant> {
+    return await this.merchantDataService.create(merchant.name);
+  }
+
+  public async update(merchant: UpdateMerchantDto): Promise<Merchant> {
+    return await this.merchantDataService.update(merchant);
+  }
+
+  public async remove(id: string): Promise<void> {
+    await this.merchantDataService.delete(id);
+  }
+}

src/services/expenses.service.ts

@@ -1,141 +0,0 @@
-import { Injectable } from '@nestjs/common';
-import { Category, Expense, Merchant, SubCategory, Tag } from '../controllers/expenses/expense.entities';
-import { CreateExpenseDto, GetExpenseDto, UpdateExpenseDto } from '../controllers/expenses/expense.dto';
-import { randomUUID } from 'node:crypto';
-
-@Injectable()
-export class ExpensesService {
-  private categories: Category[] = [
-    {
-      id: '1',
-      category: 'Category 1'
-    }
-  ];
-  private merchants: Merchant[] = [
-    {
-      id: '1',
-      merchant: 'Merchant 1'
-    }
-  ];
-  private subcategories: SubCategory[] = [
-    {
-      id: '1',
-      subcategory: 'Subcategory 1'
-    },
-    {
-      id: '2',
-      subcategory: 'Subcategory 2'
-    }
-  ];
-  private tags: Tag[] = [
-    {
-      id: '1',
-      tag: 'Tag 1'
-    },
-    {
-      id: '2',
-      tag: 'Tag 2'
-    }
-  ];
-  private expenses: Expense[] = [
-    {
-      id: '2aa94170-2c57-4c4f-a1e7-13544ba72917',
-      date: new Date('2025-12-01'),
-      cents: 15443,
-      categoryId: '1',
-      merchantId: '1',
-      subcategoryIds: ['1', '2'],
-      tagIds: ['1', '2'],
-      description: 'Full existing expense'
-    },
-    {
-      id: '0708e7f7-3a2a-4b93-81da-38954925ca78',
-      date: new Date('2025-12-02'),
-      cents: 8723,
-      categoryId: '1',
-      subcategoryIds: [],
-      tagIds: [],
-      description: 'Partial existing expense'
-    }
-  ];
-
-  public create(createExpenseDto: CreateExpenseDto) {
-    const expense = {
-      id: randomUUID(),
-      date: new Date(createExpenseDto.date),
-      cents: createExpenseDto.cents,
-      categoryId: createExpenseDto.categoryId,
-      merchantId: createExpenseDto.merchantId,
-      subcategoryIds: createExpenseDto.subcategoryIds ?? [],
-      tagIds: createExpenseDto.tagIds ?? [],
-      description: createExpenseDto.description
-    } as Expense;
-    this.expenses.push(expense);
-
-    return this.mapExpense(expense);
-  }
-
-  public findAll() {
-    return this.expenses.map((expense) => {
-      return this.mapExpense(expense);
-    });
-  }
-
-  public findOne(id: string) {
-    const expense = this.getExpense(id);
-    return expense ? this.mapExpense(expense) : undefined;
-  }
-
-  public update(id: string, updateExpenseDto: UpdateExpenseDto) {
-    let index;
-    const expense = this.expenses.find((exp, idx) => {
-      if (exp.id === id) {
-        index = idx;
-        return exp;
-      }
-    });
-
-    if (expense && index) {
-      this.expenses[index] = {
-        ...expense,
-        ...updateExpenseDto
-      };
-
-      return this.mapExpense(this.expenses[index]);
-    }
-
-    return undefined;
-  }
-
-  public remove(id: string) {
-    this.expenses = this.expenses.filter((expense) => expense.id !== id);
-  }
-
-  private getExpense(id: string) {
-    return this.expenses.find((expense) => expense.id === id);
-  }
-
-  private getSubcategories(ids: string[]) {
-    return this.subcategories.filter((sub) => ids.includes(sub.id)).map((s) => s.subcategory);
-  }
-
-  private getTags(ids: string[]) {
-    return this.tags.filter((tag) => ids.includes(tag.id)).map((t) => t.tag);
-  }
-
-  private mapExpense(expense: Expense) {
-    const category = this.categories.find((category) => category.id === expense.categoryId);
-    const merchant = this.merchants.find((merchant) => merchant.id === expense.merchantId);
-
-    return {
-      id: expense.id,
-      date: expense.date,
-      cents: expense.cents,
-      category: category?.category,
-      merchant: merchant?.merchant,
-      subcategories: this.getSubcategories(expense.subcategoryIds),
-      tags: this.getTags(expense.tagIds),
-      description: expense.description
-    } as GetExpenseDto;
-  }
-}

src/sub-categories/dto/create-sub-category.dto.ts

@@ -0,0 +1,3 @@
+export class CreateSubCategoryDto {
+  name: string;
+}

src/sub-categories/dto/update-sub-category.dto.ts

@@ -0,0 +1,4 @@
+export class UpdateSubCategoryDto {
+  id: string;
+  name: string;
+}

src/sub-categories/entities/sub-category.entity.ts

@@ -0,0 +1,10 @@
+import { Column, Entity, PrimaryGeneratedColumn } from 'typeorm';
+
+@Entity()
+export class SubCategory {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column()
+  name: string;
+}

src/sub-categories/sub-categories.controller.ts

@@ -0,0 +1,75 @@
+import {
+  Controller,
+  Get,
+  Post,
+  Put,
+  Delete,
+  Body,
+  Param,
+  HttpCode,
+  HttpStatus,
+  BadRequestException,
+  NotFoundException,
+  InternalServerErrorException
+} from '@nestjs/common';
+import { SubCategoriesService } from './sub-categories.service';
+import { CreateSubCategoryDto } from './dto/create-sub-category.dto';
+import { UpdateSubCategoryDto } from './dto/update-sub-category.dto';
+import { SubCategory } from './entities/sub-category.entity';
+
+@Controller('sub-categories')
+export class SubCategoriesController {
+  constructor(private readonly subCategoriesService: SubCategoriesService) { }
+
+  @Get()
+  @HttpCode(HttpStatus.OK)
+  public async findAll(): Promise<SubCategory[]> {
+    return await this.subCategoriesService.findAll();
+  }
+
+  @Get(':id')
+  @HttpCode(HttpStatus.OK)
+  public async findOne(@Param('id') id: string): Promise<SubCategory> {
+    if (!id) {
+      throw new BadRequestException('No ID provided.');
+    }
+
+    try {
+      return await this.subCategoriesService.findById(id);
+    }
+    catch (error) {
+      throw new NotFoundException(error);
+    }
+  }
+
+  @Post()
+  @HttpCode(HttpStatus.CREATED)
+  public async create(@Body() subCategory: CreateSubCategoryDto): Promise<SubCategory> {
+    if (!subCategory.name) {
+      throw new BadRequestException('Sub-category name cannot be empty.');
+    }
+
+    try {
+      return await this.subCategoriesService.create(subCategory);
+    }
+    catch (error) {
+      throw new InternalServerErrorException(error);
+    }
+  }
+
+  @Put()
+  @HttpCode(HttpStatus.OK)
+  public async update(@Body() subCategory: UpdateSubCategoryDto): Promise<SubCategory> {
+    if (!subCategory.id) {
+      throw new BadRequestException('Sub-category ID cannot be empty.');
+    }
+
+    return await this.subCategoriesService.update(subCategory);
+  }
+
+  @Delete(':id')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  public async remove(@Param('id') id: string): Promise<void> {
+    return await this.subCategoriesService.remove(id);
+  }
+}

src/sub-categories/sub-categories.module.ts

@@ -0,0 +1,10 @@
+import { Module } from '@nestjs/common';
+import { SubCategoriesService } from './sub-categories.service';
+import { SubCategoriesController } from './sub-categories.controller';
+import { SubCategoryDataService } from './sub-category-data.service';
+
+@Module({
+  controllers: [SubCategoriesController],
+  providers: [SubCategoriesService, SubCategoryDataService]
+})
+export class SubCategoriesModule { }

src/sub-categories/sub-categories.service.ts

@@ -0,0 +1,35 @@
+import { Injectable } from '@nestjs/common';
+import { CreateSubCategoryDto } from './dto/create-sub-category.dto';
+import { UpdateSubCategoryDto } from './dto/update-sub-category.dto';
+import { SubCategoryDataService } from './sub-category-data.service';
+import { SubCategory } from './entities/sub-category.entity';
+
+@Injectable()
+export class SubCategoriesService {
+  public constructor(private subCategoryDataService: SubCategoryDataService) { }
+
+  public async findAll(): Promise<SubCategory[]> {
+    return await this.subCategoryDataService.getAll();
+  }
+
+  public async findById(id: string): Promise<SubCategory> {
+    const subCategory = await this.subCategoryDataService.getById(id);
+    if (!subCategory) {
+      throw new Error('No sub-category found');
+    }
+
+    return subCategory;
+  }
+
+  public async create(subCategory: CreateSubCategoryDto): Promise<SubCategory> {
+    return await this.subCategoryDataService.create(subCategory.name);
+  }
+
+  public async update(subCategory: UpdateSubCategoryDto): Promise<SubCategory> {
+    return await this.subCategoryDataService.update(subCategory);
+  }
+
+  public async remove(id: string): Promise<void> {
+    await this.subCategoryDataService.delete(id);
+  }
+}

src/sub-categories/sub-category-data.service.ts

@@ -0,0 +1,33 @@
+import { Injectable } from '@nestjs/common';
+import { DataSource, Repository } from 'typeorm';
+import { SubCategory } from './entities/sub-category.entity';
+import { UpdateSubCategoryDto } from './dto/update-sub-category.dto';
+
+@Injectable()
+export class SubCategoryDataService {
+  private subCategories: Repository<SubCategory>;
+
+  public constructor(private dataSource: DataSource) {
+    this.subCategories = this.dataSource.getRepository(SubCategory);
+  }
+
+  public async getAll(): Promise<SubCategory[]> {
+    return await this.subCategories.find();
+  }
+
+  public async getById(id: string): Promise<SubCategory | null> {
+    return await this.subCategories.findOneBy({ id });
+  }
+
+  public async create(name: string): Promise<SubCategory> {
+    return await this.subCategories.save({ name });
+  }
+
+  public async update(subCategory: UpdateSubCategoryDto): Promise<SubCategory> {
+    return await this.subCategories.save(subCategory);
+  }
+
+  public async delete(id: string): Promise<void> {
+    await this.subCategories.delete({ id });
+  }
+}

src/tags/dto/create-tag.dto.ts

@@ -0,0 +1,3 @@
+export class CreateTagDto {
+  name: string;
+}

src/tags/dto/update-tag.dto.ts

@@ -0,0 +1,4 @@
+export class UpdateTagDto {
+  id: string;
+  name: string;
+}

src/tags/entities/tag.entity.ts

@@ -0,0 +1,10 @@
+import { Column, Entity, PrimaryGeneratedColumn } from 'typeorm';
+
+@Entity()
+export class Tag {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column()
+  name: string;
+}

src/tags/tag-data.service.ts

@@ -0,0 +1,33 @@
+import { Injectable } from '@nestjs/common';
+import { DataSource, Repository } from 'typeorm';
+import { Tag } from './entities/tag.entity';
+import { UpdateTagDto } from './dto/update-tag.dto';
+
+@Injectable()
+export class TagDataService {
+  private tags: Repository<Tag>;
+
+  public constructor(private dataSource: DataSource) {
+    this.tags = this.dataSource.getRepository(Tag);
+  }
+
+  public async getAll(): Promise<Tag[]> {
+    return await this.tags.find();
+  }
+
+  public async getById(id: string): Promise<Tag | null> {
+    return await this.tags.findOneBy({ id });
+  }
+
+  public async create(name: string): Promise<Tag> {
+    return await this.tags.save({ name });
+  }
+
+  public async update(tag: UpdateTagDto): Promise<Tag> {
+    return await this.tags.save(tag);
+  }
+
+  public async delete(id: string): Promise<void> {
+    await this.tags.delete({ id });
+  }
+}

src/tags/tags.controller.ts

@@ -0,0 +1,75 @@
+import {
+  Controller,
+  Get,
+  Post,
+  Put,
+  Delete,
+  Body,
+  Param,
+  HttpCode,
+  HttpStatus,
+  BadRequestException,
+  NotFoundException,
+  InternalServerErrorException
+} from '@nestjs/common';
+import { TagsService } from './tags.service';
+import { CreateTagDto } from './dto/create-tag.dto';
+import { UpdateTagDto } from './dto/update-tag.dto';
+import { Tag } from './entities/tag.entity';
+
+@Controller('tags')
+export class TagsController {
+  public constructor(private readonly tagsService: TagsService) { }
+
+  @Get()
+  @HttpCode(HttpStatus.OK)
+  public async findAll(): Promise<Tag[]> {
+    return await this.tagsService.findAll();
+  }
+
+  @Get(':id')
+  @HttpCode(HttpStatus.OK)
+  public async findOne(@Param('id') id: string): Promise<Tag> {
+    if (!id) {
+      throw new BadRequestException('No ID provided.');
+    }
+
+    try {
+      return await this.tagsService.findById(id);
+    }
+    catch (error) {
+      throw new NotFoundException(error);
+    }
+  }
+
+  @Post()
+  @HttpCode(HttpStatus.CREATED)
+  public async create(@Body() tag: CreateTagDto): Promise<Tag> {
+    if (!tag.name) {
+      throw new BadRequestException('Tag name cannot be empty.');
+    }
+
+    try {
+      return await this.tagsService.create(tag);
+    }
+    catch (error) {
+      throw new InternalServerErrorException(error);
+    }
+  }
+
+  @Put()
+  @HttpCode(HttpStatus.OK)
+  public async update(@Body() tag: UpdateTagDto): Promise<Tag> {
+    if (!tag.id) {
+      throw new BadRequestException('Tag ID cannot be empty.');
+    }
+
+    return await this.tagsService.update(tag);
+  }
+
+  @Delete(':id')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  public async remove(@Param('id') id: string): Promise<void> {
+    return await this.tagsService.remove(id);
+  }
+}

src/tags/tags.module.ts

@@ -0,0 +1,10 @@
+import { Module } from '@nestjs/common';
+import { TagsService } from './tags.service';
+import { TagsController } from './tags.controller';
+import { TagDataService } from './tag-data.service';
+
+@Module({
+  controllers: [TagsController],
+  providers: [TagsService, TagDataService]
+})
+export class TagsModule { }

src/tags/tags.service.ts

@@ -0,0 +1,35 @@
+import { Injectable } from '@nestjs/common';
+import { CreateTagDto } from './dto/create-tag.dto';
+import { UpdateTagDto } from './dto/update-tag.dto';
+import { TagDataService } from './tag-data.service';
+import { Tag } from './entities/tag.entity';
+
+@Injectable()
+export class TagsService {
+  public constructor(private tagDataService: TagDataService) { }
+
+  public async findAll(): Promise<Tag[]> {
+    return await this.tagDataService.getAll();
+  }
+
+  public async findById(id: string): Promise<Tag> {
+    const tag = await this.tagDataService.getById(id);
+    if (!tag) {
+      throw new Error('No tag found');
+    }
+
+    return tag;
+  }
+
+  public async create(tag: CreateTagDto): Promise<Tag> {
+    return await this.tagDataService.create(tag.name);
+  }
+
+  public async update(tag: UpdateTagDto): Promise<Tag> {
+    return await this.tagDataService.update(tag);
+  }
+
+  public async remove(id: string): Promise<void> {
+    await this.tagDataService.delete(id);
+  }
+}