feat: add product variant management functionality

- Implemented CreateProductVariantDto and UpdateProductVariantDto for product variant data transfer.
- Developed ProductVariantsController to handle CRUD operations for product variants.
- Created ProductVariantsService to interact with the database using Prisma.
- Added ProductVariantsModule to encapsulate the product variant feature.
- Included response mapping for consistent API responses.

src/products/dto/create-product.dto.ts

@@ -1,15 +1,29 @@
+import { Type } from 'class-transformer'
+import { IsInt, IsOptional, IsString } from 'class-validator'
+
 export class CreateProductDto {
+  @IsString()
   name: string
-  description?: string
+
+  @IsOptional()
+  @IsString()
   sku?: string
+
+  @IsOptional()
+  @IsString()
   barcode?: string
-  imageUrl?: string
-  attachmentId?: number
-  unit: string
-  discount?: number
-  quantity?: number
-  alertQuantity?: number
-  isActive?: boolean
-  isFeatured?: boolean
-  productInfoId: number
+
+  @IsOptional()
+  @IsString()
+  description?: string
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  brandId?: number
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  categoryId?: number
 }

src/products/dto/update-product.dto.ts

@@ -1,15 +1,30 @@
+import { Type } from 'class-transformer'
+import { IsInt, IsOptional, IsString } from 'class-validator'
+
 export class UpdateProductDto {
+  @IsOptional()
+  @IsString()
   name?: string
-  description?: string
+
+  @IsOptional()
+  @IsString()
   sku?: string
+
+  @IsOptional()
+  @IsString()
   barcode?: string
-  imageUrl?: string
-  attachmentId?: number
-  unit?: string
-  discount?: number
-  quantity?: number
-  alertQuantity?: number
-  isActive?: boolean
-  isFeatured?: boolean
-  productInfoId?: number
+
+  @IsOptional()
+  @IsString()
+  description?: string
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  brandId?: number
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  categoryId?: number
 }

src/products/products.controller.ts

@@ -9,6 +9,7 @@ export class ProductsController {
 
   @Post()
   create(@Body() dto: CreateProductDto) {
+    console.log('[ProductController] create called', dto)
     return this.productsService.create(dto)
   }
 

src/products/products.service.ts

@@ -1,27 +1,86 @@
 import { Injectable } from '@nestjs/common'
+import { ResponseMapper } from '../common/response/response-mapper'
 import { PrismaService } from '../prisma/prisma.service'
+import { CreateProductDto } from './dto/create-product.dto'
 
 @Injectable()
 export class ProductsService {
   constructor(private prisma: PrismaService) {}
 
-  create(data: any) {
-    return this.prisma.product.create({ data })
+  async create(data: CreateProductDto) {
+    console.log(data)
+
+    // Transform incoming DTO so relation ids are passed as `connect` objects
+    const payload: any = { ...data }
+    // If the client supplied brandId/categoryId (even null), remove the scalar
+    // Prisma expects nested relation objects, so only add `connect` when an id is present.
+    if (Object.prototype.hasOwnProperty.call(payload, 'brandId')) {
+      if (payload.brandId !== undefined && payload.brandId !== null) {
+        payload.brand = { connect: { id: Number(payload.brandId) } }
+      }
+      delete payload.brandId
+    }
+
+    if (Object.prototype.hasOwnProperty.call(payload, 'categoryId')) {
+      if (payload.categoryId !== undefined && payload.categoryId !== null) {
+        payload.category = { connect: { id: Number(payload.categoryId) } }
+      }
+      delete payload.categoryId
+    }
+
+    const item = await this.prisma.product.create({ data: payload })
+    return ResponseMapper.create(item)
   }
 
-  findAll() {
-    return this.prisma.product.findMany()
+  async findAll() {
+    const items = await this.prisma.product.findMany({
+      include: { brand: true, category: true },
+    })
+    const mapped = items.map(p => {
+      const { brandId, categoryId, ...rest } = p as any
+      return { ...rest, brand: p.brand, category: p.category }
+    })
+    return ResponseMapper.list(mapped)
   }
 
-  findOne(id: number) {
-    return this.prisma.product.findUnique({ where: { id } })
+  async findOne(id: number) {
+    const p = await this.prisma.product.findUnique({
+      where: { id },
+      include: { brand: true, category: true },
+    })
+    if (!p) return null
+
+    console.log('first')
+
+    const { brandId, categoryId, ...rest } = p as any
+    return ResponseMapper.single({ ...rest, brand: p.brand, category: p.category })
   }
 
-  update(id: number, data: any) {
-    return this.prisma.product.update({ where: { id }, data })
+  async update(id: number, data: any) {
+    const payload: any = { ...data }
+    if (Object.prototype.hasOwnProperty.call(payload, 'brandId')) {
+      if (payload.brandId === null) {
+        payload.brand = { disconnect: true }
+      } else {
+        payload.brand = { connect: { id: Number(payload.brandId) } }
+      }
+      delete payload.brandId
+    }
+    if (Object.prototype.hasOwnProperty.call(payload, 'categoryId')) {
+      if (payload.categoryId === null) {
+        payload.category = { disconnect: true }
+      } else {
+        payload.category = { connect: { id: Number(payload.categoryId) } }
+      }
+      delete payload.categoryId
+    }
+
+    const item = await this.prisma.product.update({ where: { id }, data: payload })
+    return ResponseMapper.update(item)
   }
 
-  remove(id: number) {
-    return this.prisma.product.delete({ where: { id } })
+  async remove(id: number) {
+    const item = await this.prisma.product.delete({ where: { id } })
+    return ResponseMapper.single(item)
   }
 }