Arkos Bug: Duplicate DTOs In Model Relations

by Alex Johnson 45 views

This article addresses a bug encountered while using Arkos to generate Data Transfer Objects (DTOs) for Prisma models, specifically when a model has multiple relations with another model. The issue results in the same DTO class being incorrectly generated for both relations, leading to potential confusion and errors in data handling. Let's dive into the details of the problem, analyze the cause, and explore possible solutions.

The Problem: Duplicate DTO Generation

The core issue arises when generating DTOs for a Prisma model that has two or more relations with the same model. In such scenarios, Arkos incorrectly generates the same DTO class for each relation, instead of creating distinct DTOs that accurately represent the specific relationship. This can lead to problems when updating or transferring data, as the system might not be able to differentiate between the different relations, potentially leading to data corruption or unexpected behavior. To illustrate this, let's examine the provided Prisma model and the resulting DTO generation.

Illustrative Scenario: The Staff Model

Consider the following Prisma model, named Staff, which showcases the problematic scenario:

model Staff {
  id        String    @id @default(uuid())
  createdAt DateTime  @default(now())
  deletedAt DateTime?

  code      String      @unique
  name      String
  email     String?     @unique
  signature String?
  photo     String?
  gender    StaffGender
  nuit      String?
  idCard    String?

  departmentId String
  department   Department @relation(fields: [departmentId], references: [id], onDelete: Cascade)

  addressId String?
  address   Address? @relation(fields: [addressId], references: [id], onDelete: Cascade)

  locationId String
  location   Address @relation("StaffLocationToAdress", fields: [locationId], references: [id], onDelete: Cascade)
  user       User?
}

enum StaffGender {
  Male
  Female
}

In this model, the Staff entity has two relations with the Address model: address and location. The address field represents the staff's residential address, while the location field (using the StaffLocationToAdress relation name) represents the staff's work location. When generating DTOs for this model using the command npx arkos g ud -m staff, the following UpdateStaffDto is produced:

import { IsOptional, IsString, IsEnum, ValidateNested } from "class-validator";
import { Type } from "class-transformer";
import { StaffGender } from "@prisma/client";

class DepartmentForUpdateStaffDto {
  @IsOptional()
  @IsString()
  id!: string;
}

class AddressForUpdateStaffDto {
  @IsOptional()
  @IsString()
  id!: string;
}

class AddressForUpdateStaffDto {
  @IsOptional()
  @IsString()
  id!: string;
}

class UserForUpdateStaffDto {
  @IsOptional()
  @IsString()
  id!: string;
}

export default class UpdateStaffDto {
  @IsOptional()
  @IsString()
  code?: string;

  @IsOptional()
  @IsString()
  name?: string;

  @IsOptional()
  @IsString()
  email?: string;

  @IsOptional()
  @IsString()
  signature?: string;

  @IsOptional()
  @IsString()
  photo?: string;

  @IsOptional()
  @IsEnum(StaffGender)
  gender?: StaffGender;

  @IsOptional()
  @IsString()
  nuit?: string;

  @IsOptional()
  @IsString()
  idCard?: string;

  @IsOptional()
  @ValidateNested()
  @Type(() => DepartmentForUpdateStaffDto)
  department?: DepartmentForUpdateStaffDto;

  @IsOptional()
  @ValidateNested()
  @Type(() => AddressForUpdateStaffDto)
  address?: AddressForUpdateStaffDto;

  @IsOptional()
  @ValidateNested()
  @Type(() => AddressForUpdateStaffDto)
  location?: AddressForUpdateStaffDto;

  @IsOptional()
  @ValidateNested()
  @Type(() => UserForUpdateStaffDto)
  user?: UserForUpdateStaffDto;
}

As you can see, the AddressForUpdateStaffDto class is generated twice, and both the address and location fields in the UpdateStaffDto use the same AddressForUpdateStaffDto. This is incorrect, as it doesn't allow for specific handling or validation rules for the two distinct address relations. This duplication highlights the core bug.

Understanding the Root Cause

The underlying cause of this issue likely stems from the way Arkos identifies and processes relations during DTO generation. When encountering multiple relations with the same model, the generation logic might not be distinguishing them based on their relation names or field names. Instead, it might be simply identifying the target model (Address in this case) and generating a single DTO for it, which is then reused for all relations with that model. This is a simplification that works for single relations but breaks down when multiple relations to the same model exist.

Potential Areas of the Arkos Codebase to Investigate

To pinpoint the exact location of the bug, one would need to delve into the Arkos codebase. Here are some potential areas to focus on:

  1. Relation Processing Logic: The code responsible for identifying and processing model relations is a prime suspect. This code needs to be examined to see how it handles multiple relations to the same model.
  2. DTO Generation Logic: The part of the code that generates DTO classes based on model relations needs to be inspected. It should correctly generate distinct DTOs for different relations, even if they point to the same model.
  3. Naming Conventions: The naming conventions used for generated DTOs might be a factor. If the naming logic doesn't incorporate relation names or field names, it could lead to naming conflicts and the generation of duplicate DTOs.

Proposed Solutions and Workarounds

While a proper fix requires modifying the Arkos codebase, there are some potential workarounds and solutions that can be employed in the meantime.

1. Manual DTO Modification

The most straightforward workaround is to manually modify the generated DTOs. This involves:

  • Renaming one of the duplicate DTO classes (e.g., AddressForUpdateStaffDto to LocationForUpdateStaffDto).
  • Updating the UpdateStaffDto to use the correct DTO class for each relation.

This approach provides immediate relief but requires manual intervention every time DTOs are generated.

2. Custom DTO Generation Script

A more robust solution involves creating a custom script that generates DTOs based on the Prisma schema. This script can incorporate the necessary logic to correctly handle multiple relations, ensuring that distinct DTOs are generated for each relation. This approach requires more initial effort but provides a long-term solution that avoids manual modifications.

3. Contributing to Arkos

The ideal solution is to contribute a fix to the Arkos project itself. This involves:

  • Identifying the bug's location in the Arkos codebase.
  • Implementing a fix that correctly handles multiple relations.
  • Submitting a pull request to the Arkos repository.

This approach benefits the entire Arkos community and ensures that the bug is permanently resolved.

4. Using Prisma Selectors

Prisma Selectors offer a way to precisely define the data you want to retrieve or update. By using selectors, you can shape the data according to your needs, potentially mitigating the need for separate DTOs in some cases. While this doesn't directly solve the DTO generation bug, it provides an alternative approach for data handling that might be suitable for certain scenarios.

Importance of Distinct DTOs

The need for distinct DTOs for different relations might not be immediately obvious, but it's crucial for several reasons:

  1. Data Integrity: Different relations might have different validation rules or data constraints. Using the same DTO for both relations can lead to invalid data being accepted.
  2. Code Clarity: Distinct DTOs make the code more readable and maintainable. It's easier to understand the purpose of each DTO when it's clearly associated with a specific relation.
  3. Flexibility: Distinct DTOs allow for greater flexibility in data handling. You can easily modify the structure or validation rules of one DTO without affecting the others.

Conclusion

The bug in Arkos that causes duplicate DTOs to be generated for models with multiple relations is a significant issue that needs to be addressed. While workarounds and alternative solutions exist, the ideal approach is to fix the underlying problem in Arkos itself. By understanding the root cause and implementing appropriate solutions, we can ensure that DTO generation is accurate and efficient, leading to more robust and maintainable applications. Remember, distinct DTOs are crucial for data integrity, code clarity, and overall flexibility in data handling.

For more information about Prisma and DTOs, you can refer to the official Prisma documentation on their website: Prisma Documentation