Nest + TypeORM

NestJS

Middleware

• Is a function call before router handler

Exception filter

• When an exception not handle by your code, it's catch by this then send user-friendly response

Pipe

• Transformation: From string to integer

• Validation: Evaluate input data if valid, otherwise throw exception

Guard

• Determine whether a given request will be handled by the route handler or not, Have access to the ExecutionContext instance

Interceptor

• Interceptor(ExecutionContext, CallHandler), modify response P

• Transform the result return from controller before send to client

• Bind extra logic before/ after method execution

TypeORM

Model define

@Entity({ name: 'Brands' })
export class Brand {
  @PrimaryGeneratedColumn()
  id: number;
}

ManyToOne

@Column()
category_id: number;
@ManyToOne(() => Category, (category) => category.brands, {
  cascade: true,
  onDelete: 'CASCADE',
})
@JoinColumn({ name: 'category_id' })
category: Category;

• Define ManyToOne is define foreign key constraint

• Use @OneToMany, @ManyToOne is required

• @ManyToOne(() => Category), this line will create column "categoryId“ in the table, to change change this name can specify the join column name @JoinColumn({ name: "category_id" })

Notes

• nest g module --name for modules nest g controller --name for controller nest g service for --name for service

• constructor (private readonly name: serviceName)

• @Get() /items @Get('id') /item/id

• getAll(@Param('id') id: string)

• itemRepository extract item from tbale

• fix metadata was not found => import typeorm module forFeature