Multi tool use

NodeJS map Dtos to TypeORM Entities

I have a nodejs REST API backend running the nestjs framework, using typeORM as ORM for my entities.

nodejs

nestjs

Coming from a C#/Entity Framework background, I am very used to have my Dtos mapped to the database entities.

C#/Entity Framework

Is there a similar approach with typeORM?

I have seen the automapper-ts library, but those magic strings in the map declarations look kind of scary...
Basically it would be amazing if I could :

let user: TypeORMUserEntity = mapper.map<TypeORMUserEntity>(userDto);


What is the way to do this (or any alternative with same result) in nodejs/typeorm backend environment?

1 Answer
1

You can use class-transformer library. You can use it with class-validator to cast and validate POST parameters.

Example:

@Exclude()
class SkillNewDto {
@Expose()
@ApiModelProperty({ required: true })
@IsString()
@MaxLength(60)
name: string;

@Expose()
@ApiModelProperty({
required: true,
type: Number,
isArray: true,
})
@IsArray()
@IsInt({ each: true })
@IsOptional()
categories: number;
}


Exclude and Expose here are from class-transform to avoid additional fields.

Exclude

Expose

class-transform

IsString, IsArray, IsOptional, IsInt, MaxLength are from class-validator.

IsString

IsArray

IsOptional

IsInt

MaxLength

class-validator

ApiModelProperty is for Swagger documentation

ApiModelProperty

And then

const skillDto = plainToClass(SkillNewDto, body);
const errors = await validate(skillDto);
if (errors.length) {
throw new BadRequestException('Invalid skill', this.modelHelper.modelErrorsToReadable(errors));
}


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