added merchants resource

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 getAllMerchants(): Promise<Merchant[]> {
+    return this.merchants.find();
+  }
+
+  public async getMerchantById(id: string): Promise<Merchant | null> {
+    return await this.merchants.findOneBy({ id });
+  }
+
+  public async createMerchant(name: string): Promise<Merchant> {
+    return await this.merchants.save({ name });
+  }
+
+  public async updateMerchant(updateMerchant: UpdateMerchantDto): Promise<Merchant> {
+    return await this.merchants.save(updateMerchant);
+  }
+
+  public async deleteMerchant(id: string): Promise<void> {
+    await this.merchants.delete({ id });
+  }
+}