Validation

Strata uses layered validation — each layer validates what it owns.

Layer 1: Presentation (DTO)

Request DTOs use class-validator decorators for shape and type validation.

presentation/dto/asset/create-asset.dto.ts

export class CreateAssetDto {
  @IsString()
  @IsNotEmpty()
  name: string;

  @IsUUID()
  assetTypeId: string;

  @IsOptional()
  @IsString()
  quantity?: string;
}

Invalid requests receive a 400 Bad Request with validation error details.

Layer 2: Application (Use Case)

Services check business preconditions — entity existence, authorization, etc.

application/services/asset.service.ts

const assetType = await this.assetTypeRepo.findById(command.assetTypeId);
if (!assetType) throw new AssetTypeNotFoundException(command.assetTypeId);

Layer 3: Domain (Entity)

Domain entities enforce business invariants in their constructors or methods.

Layer 4: Infrastructure (Database)

Prisma enforces @unique constraints, foreign keys, and data types. The repository layer catches Prisma errors and translates them to domain exceptions.

Exception Mapping

Domain exceptions are mapped to HTTP status codes by the DomainExceptionFilter:

Exception	HTTP Status
AssetNotFoundException	404
CategoryNotFoundException	404
TagNotFoundException	404
AssetTypeNotFoundException	404
DuplicateNameException	409
CategoryHasChildrenException	409