improvement: error handeling structure changed and unified all across the app. user no longer sees inappropriate messages.

backend/src/common/errors/validation-exception.factory.ts

@@ -0,0 +1,73 @@
+import { BadRequestException, HttpException, HttpStatus } from '@nestjs/common';
+import type { ValidationError } from 'class-validator';
+import { AppException } from './app.exception';
+import { ErrorCode, type ErrorCodeValue, type ValidationErrorDetail } from './error-codes';
+
+const KNOWN_VALIDATION_CODES = new Set<string>(Object.values(ErrorCode));
+
+function isKnownValidationCode(value: string): value is ErrorCodeValue {
+  return KNOWN_VALIDATION_CODES.has(value);
+}
+
+function constraintToCode(constraintKey: string, message: string): ErrorCodeValue {
+  if (isKnownValidationCode(message)) {
+    return message;
+  }
+
+  switch (constraintKey) {
+    case 'isEmail':
+      return ErrorCode.VALIDATION_EMAIL_INVALID;
+    case 'minLength':
+      return ErrorCode.VALIDATION_PASSWORD_TOO_SHORT;
+    case 'isEnum':
+      return ErrorCode.VALIDATION_ORGANIZATION_TYPE_INVALID;
+    case 'matches':
+      return ErrorCode.VALIDATION_MOBILE_INVALID;
+    case 'isIn':
+      return ErrorCode.VALIDATION_LANGUAGE_INVALID;
+    case 'whitelistValidation':
+      return ErrorCode.VALIDATION_INVALID_REQUEST;
+    default:
+      return ErrorCode.VALIDATION_FIELD_REQUIRED;
+  }
+}
+
+function flattenValidationErrors(
+  errors: ValidationError[],
+  parentPath = '',
+): ValidationErrorDetail[] {
+  const details: ValidationErrorDetail[] = [];
+
+  for (const error of errors) {
+    const field = parentPath ? `${parentPath}.${error.property}` : error.property;
+
+    if (error.constraints) {
+      const [constraintKey, message] = Object.entries(error.constraints)[0];
+      details.push({
+        field,
+        code: constraintToCode(constraintKey, message),
+      });
+    }
+
+    if (error.children?.length) {
+      details.push(...flattenValidationErrors(error.children, field));
+    }
+  }
+
+  return details;
+}
+
+export function validationExceptionFactory(errors: ValidationError[]): HttpException {
+  const details = flattenValidationErrors(errors);
+
+  if (details.length === 0) {
+    return new AppException(ErrorCode.VALIDATION_FAILED, HttpStatus.BAD_REQUEST);
+  }
+
+  return new AppException(ErrorCode.VALIDATION_FAILED, HttpStatus.BAD_REQUEST, details);
+}
+
+/** Handles forbidNonWhitelisted errors from ValidationPipe. */
+export function isValidationPipeBadRequest(exception: unknown): exception is BadRequestException {
+  return exception instanceof BadRequestException;
+}