feat: add IsNotBlank decorator and corresponding tests

README.md

@@ -62,6 +62,8 @@ import {
   IsInt,
   Length,
   IsEmail,
+  IsNotBlank,
+  IsString,
   IsFQDN,
   IsDate,
   Min,
@@ -83,6 +85,10 @@ export class Post {
   @IsEmail()
   email: string;
 
+  @IsString()
+  @IsNotBlank()
+  username: string;
+
   @IsFQDN()
   site: string;
 

src/decorator/common/IsNotBlank.ts

@@ -0,0 +1,44 @@
+import { ValidationOptions } from '../ValidationOptions';
+import { buildMessage, ValidateBy } from './ValidateBy';
+
+export const IS_NOT_BLANK = 'isNotBlank';
+
+/**
+ * @param value The value to be checked
+ * @returns true if the value is not blank, false otherwise
+ * @description
+ * The value is considered blank if it is null, undefined or empty string
+ * @description
+ * Non-string values is considered not blank
+ */
+export function isNotBlank(value: unknown): boolean {
+  if (value == null) return false;
+
+  if (typeof value === 'string') return value.trim().length > 0;
+
+  return true;
+}
+
+/**
+ * @param validationOptions The validation options
+ * @returns {PropertyDecorator}
+ *
+ * @description
+ * The decorator checks if the value is not blank
+ * @description
+ * The value is considered blank if it is null, undefined or empty string
+ * @description
+ * Non-string values is considered not blank
+ */
+export function IsNotBlank(validationOptions?: ValidationOptions): PropertyDecorator {
+  return ValidateBy(
+    {
+      name: IS_NOT_BLANK,
+      validator: {
+        validate: (value): boolean => isNotBlank(value),
+        defaultMessage: buildMessage(eachPrefix => eachPrefix + '$property should not be blank', validationOptions),
+      },
+    },
+    validationOptions
+  );
+}

src/decorator/decorators.ts

@@ -21,6 +21,7 @@ export * from './common/Equals';
 export * from './common/NotEquals';
 export * from './common/IsEmpty';
 export * from './common/IsNotEmpty';
+export * from './common/IsNotBlank';
 export * from './common/IsIn';
 export * from './common/IsNotIn';
 

test/functional/validation-functions-and-decorators.spec.ts

@@ -124,6 +124,8 @@ import {
   notEquals,
   isEmpty,
   isNotEmpty,
+  IsNotBlank,
+  isNotBlank,
   isIn,
   isNotIn,
   isDateString,
@@ -422,7 +424,7 @@ describe('IsEmpty', () => {
 });
 
 describe('IsNotEmpty', () => {
-  const validValues = ['a', 'abc'];
+  const validValues = ['a', 'abc', '  ', 0, 1];
   const invalidValues = ['', undefined, null];
 
   class MyClass {
@@ -453,6 +455,38 @@ describe('IsNotEmpty', () => {
   });
 });
 
+describe('IsNotBlank', () => {
+  const validValues = ['a', 'abc', 0, 1, new Object(), [], new Date(), true, false];
+  const invalidValues = ['', undefined, null, '  '];
+
+  class MyClass {
+    @IsNotBlank()
+    someProperty: string;
+  }
+
+  it('should not fail if validator.validate said that its valid', () => {
+    return checkValidValues(new MyClass(), validValues);
+  });
+
+  it('should fail if validator.validate said that its invalid', () => {
+    return checkInvalidValues(new MyClass(), invalidValues);
+  });
+
+  it('should not fail if method in validator said that its valid', () => {
+    validValues.forEach(value => expect(isNotBlank(value)).toBeTruthy());
+  });
+
+  it('should fail if method in validator said that its invalid', () => {
+    invalidValues.forEach(value => expect(isNotBlank(value)).toBeFalsy());
+  });
+
+  it('should return error object with proper data', () => {
+    const validationType = 'isNotBlank';
+    const message = 'someProperty should not be blank';
+    return checkReturnedError(new MyClass(), invalidValues, validationType, message);
+  });
+});
+
 describe('IsIn', () => {
   const constraint = ['foo', 'bar'] as const;
   const validValues = ['foo', 'bar'];