refactor: improve error message of isenum validator

packages/custom-decorators/package.json

@@ -36,7 +36,8 @@
     "url": "https://github.com/algoan/nestjs-components/issues"
   },
   "dependencies": {
-    "jwt-decode": "^4.0.0"
+    "jwt-decode": "^4.0.0",
+    "class-validator": "^0.14.0"
   },
   "peerDependencies": {
     "@nestjs/common": ">=8",

packages/custom-decorators/src/is-enum.decorator.ts

@@ -0,0 +1,36 @@
+import { buildMessage, isEnum, ValidateBy, ValidationOptions } from 'class-validator';
+
+const IS_ENUM = 'isEnum';
+
+/**
+ * Returns the possible values from an enum (both simple number indexed and string indexed enums).
+ */
+// eslint-disable-next-line
+function validEnumValues(entity: any): string[] {
+  return (
+    Object.entries(entity)
+      // @ts-ignore
+      // eslint-disable-next-line
+      .filter(([key, value]) => isNaN(parseInt(key)))
+      // @ts-ignore
+      .map(([key, value]) => value as string)
+  );
+}
+
+export function IsEnum(entity: object, validationOptions?: ValidationOptions): PropertyDecorator {
+  return ValidateBy(
+    {
+      name: IS_ENUM,
+      constraints: [entity, validEnumValues(entity)],
+      validator: {
+        validate: (value, args): boolean => isEnum(value, args?.constraints[0]),
+        defaultMessage: buildMessage(
+          (eachPrefix) =>
+            `${eachPrefix}$property has the value $value but must be one of the following values: $constraint2`,
+          validationOptions,
+        ),
+      },
+    },
+    validationOptions,
+  );
+}

packages/custom-decorators/test/is-enum-decorator.test.ts

@@ -0,0 +1,79 @@
+import { IsEnum } from '../src/is-enum.decorator';
+import { Validator, ValidatorOptions } from 'class-validator';
+
+function validateValues(
+  object: { testProperty: any },
+  values: any[],
+  validatorOptions?: ValidatorOptions,
+): Promise<any> {
+  const validator = new Validator();
+  const promises = values.map((value) => {
+    object.testProperty = value;
+    return validator.validate(object, validatorOptions).then((errors) => {
+      expect(errors.length).toEqual(0);
+      if (errors.length > 0) {
+        console.log(`Unexpected errors: ${JSON.stringify(errors)}`);
+        throw new Error('Unexpected validation errors');
+      }
+    });
+  });
+
+  return Promise.all(promises);
+}
+
+function checkReturnedError(
+  object: { testProperty: any },
+  values: any[],
+  validationType: string,
+  messages: string[],
+  validatorOptions?: ValidatorOptions,
+): Promise<any> {
+  let messagesIncrementor: number = 0;
+  const validator = new Validator();
+  const promises = values.map((value) => {
+    object.testProperty = value;
+    return validator.validate(object, validatorOptions).then((errors) => {
+      expect(errors.length).toEqual(1);
+      expect(errors[0].target).toEqual(object);
+      expect(errors[0].property).toEqual('testProperty');
+      expect(errors[0].constraints).toEqual({ [validationType]: messages[messagesIncrementor] });
+      expect(errors[0].value).toEqual(value);
+      messagesIncrementor++;
+    });
+  });
+
+  return Promise.all(promises);
+}
+
+describe('Tests related to the custom IsEnum Decorator', () => {
+  enum CustomEnum {
+    FIRST_ITEM = 'first-item',
+    SECOND_ITEM = 'second-item',
+  }
+
+  class TestClass {
+    @IsEnum(CustomEnum)
+    testProperty: CustomEnum;
+  }
+
+  it('should validate the correct values', () => {
+    return validateValues(new TestClass(), [
+      CustomEnum.FIRST_ITEM,
+      CustomEnum.SECOND_ITEM,
+      'first-item',
+      'second-item',
+    ]);
+  });
+
+  it('should not validate invalid values and return the correct errors', () => {
+    const validationType = 'isEnum';
+    const firstMessage =
+      'testProperty has the value false-value-1 but must be one of the following values: first-item, second-item';
+    const secondMessage =
+      'testProperty has the value false-value-2 but must be one of the following values: first-item, second-item';
+    return checkReturnedError(new TestClass(), ['false-value-1', 'false-value-2'], validationType, [
+      firstMessage,
+      secondMessage,
+    ]);
+  });
+});

tsconfig.json

@@ -25,7 +25,8 @@
 
     /* Experimental Options */                
     "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
-    "emitDecoratorMetadata": true          /* Enables experimental support for emitting type metadata for decorators. */
+    "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
+    "strictPropertyInitialization": false,      /* Disables mandatory property initialization */
   },
   "include": [
     "packages/*/src/**/*",