add folder operation and use createQueryRunner

src/Operations/dto/operations.dto.ts

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+import { IsInt, IsNotEmpty, Min } from "class-validator";
+
+export class chargePrintDto {
+
+  @IsInt()
+  @IsNotEmpty()
+  @Min(1)
+  monto:number
+
+  @IsInt()
+  @Min(1)
+  @IsNotEmpty()
+  numero_hojas: number;
+
+  @IsInt()
+  @IsNotEmpty()
+  id_cuenta: number;
+}

src/Operations/operations.controller.ts

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+import { Controller } from "@nestjs/common";
+import { OperationsService } from "./operations.services";
+
+@Controller('operations')
+export class OperationsController{
+    constructor(private readonly operationsService:OperationsService){}
+
+    
+}

src/Operations/operations.module.ts

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+import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { Student } from 'src/alumno/entities/student.entity';
+import { DetalleServicio } from 'src/detalle_servicio/entities/detalle_servicio.entity';
+import { OperationsController } from './operations.controller';
+import { OperationsService } from './operations.services';
+
+@Module({
+  imports: [
+    TypeOrmModule.forFeature([Student, DetalleServicio]), // entidades que usarán las transacciones
+  ],
+  controllers: [OperationsController],
+  providers: [OperationsService],
+})
+export class OperationsModule {}

src/Operations/operations.services.ts

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+import { BadRequestException, Injectable } from '@nestjs/common';
+import { StudentService } from 'src/alumno/student.service';
+import { DetalleServicioService } from 'src/detalle_servicio/detalle_servicio.service';
+import { DataSource } from 'typeorm';
+import { chargePrintDto } from './dto/operations.dto';
+import { CreateDetalleServicioDto } from 'src/detalle_servicio/dto/create-detalle_servicio.dto';
+
+@Injectable()
+export class OperationsService {
+  constructor(
+    private readonly dataSource: DataSource,
+    private readonly studentService: StudentService,
+    private readonly detalleServicioService: DetalleServicioService,
+  ) {}
+
+  async chargePrint(data: chargePrintDto, userId: number) {
+    const { monto, id_cuenta } = data;
+
+    const queryRunner = this.dataSource.createQueryRunner();
+    await queryRunner.connect();
+    await queryRunner.startTransaction();
+
+    try {
+      const credit = await this.studentService.GetCredit(id_cuenta);
+
+      if (credit < monto) {
+        throw new BadRequestException('Crédito insuficiente');
+      }
+
+      const detalleData: CreateDetalleServicioDto = {
+        ...data,
+        id_servicio: 1,
+        id_usuario: userId,
+        fecha_operacion: new Date(),
+      };
+
+      await this.detalleServicioService.Create(detalleData, queryRunner.manager);
+
+      await this.studentService.UpdateCredit(
+        id_cuenta,
+        monto,
+        queryRunner.manager,
+      );
+
+      await queryRunner.commitTransaction();
+      return { message: 'correct' };
+    } catch (error) {
+      await queryRunner.rollbackTransaction();
+      return { message: 'error', error: error.message };
+    } finally {
+      await queryRunner.release();
+    }
+  }
+}