feat: add IsBigInt decorator

README.md

@@ -811,6 +811,7 @@ isBoolean(value);
 | `@IsString()`                                          | Checks if the value is a string.                                                                                                                                                                      |
 | `@IsNumber(options: IsNumberOptions)`                  | Checks if the value is a number.                                                                                                                                                                      |
 | `@IsInt()`                                             | Checks if the value is an integer number.                                                                                                                                                             |
+| `@IsBigInt()`                                          | Checks if the value is a bigint number.                                                                                                                                                               |
 | `@IsArray()`                                           | Checks if the value is an array                                                                                                                                                                       |
 | `@IsEnum(entity: object)`                              | Checks if the value is a valid enum                                                                                                                                                                   |
 | **Number validation decorators**                       |

src/decorator/decorators.ts

@@ -121,6 +121,7 @@ export * from './string/is-iso4217-currency-code';
 // Type checkers
 // -------------------------------------------------------------------------
 
+export * from './typechecker/IsBigInt';
 export * from './typechecker/IsBoolean';
 export * from './typechecker/IsDate';
 export * from './typechecker/IsNumber';

src/decorator/typechecker/IsBigInt.ts

@@ -0,0 +1,27 @@
+import { ValidationOptions } from '../ValidationOptions';
+import { buildMessage, ValidateBy } from '../common/ValidateBy';
+
+export const IS_BIGINT = 'isBigInt';
+
+/**
+ * Checks if the value is a bigint
+ */
+export function isBigInt(val: unknown): val is bigint {
+  return typeof val === 'bigint';
+}
+
+/**
+ * Checks if the value is a bigint
+ */
+export function IsBigInt(validationOptions?: ValidationOptions): PropertyDecorator {
+  return ValidateBy(
+    {
+      name: IS_BIGINT,
+      validator: {
+        validate: (value, args): boolean => isBigInt(value),
+        defaultMessage: buildMessage(eachPrefix => eachPrefix + '$property must be a bigint number', validationOptions),
+      },
+    },
+    validationOptions
+  );
+}

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

@@ -67,6 +67,7 @@ import {
   ArrayNotContains,
   ArrayUnique,
   IsArray,
+  IsBigInt,
   IsDateString,
   IsInstance,
   IsPhoneNumber,
@@ -79,6 +80,7 @@ import {
   isDefined,
   isNumber,
   isURL,
+  isBigInt,
   isBoolean,
   isString,
   isInt,
@@ -757,6 +759,40 @@ describe('IsInt', () => {
   });
 });
 
+describe('IsBigInt', () => {
+  // By casting bigints via function instead of `2n` annotation we can avoid
+  // to bump the typescript build target from es2018 to es2020
+  const validValues = [BigInt(2), BigInt(4), BigInt(100), BigInt(1000)];
+  const invalidValues = ['01', '-01', '000', '100e10', '123.123', '   ', '', 10, 2.5, -0.1];
+
+  class MyClass {
+    @IsBigInt()
+    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(isBigInt(value)).toBeTruthy());
+  });
+
+  it('should fail if method in validator said that its invalid', () => {
+    invalidValues.forEach(value => expect(isBigInt(value as any)).toBeFalsy());
+  });
+
+  it('should return error object with proper data', () => {
+    const validationType = 'isBigInt';
+    const message = 'someProperty must be a bigint number';
+    return checkReturnedError(new MyClass(), invalidValues, validationType, message);
+  });
+});
+
 describe('IsString', () => {
   const validValues = ['true', 'false', 'hello', '0', '', '1'];
   const invalidValues = [true, false, 1, 2, null, undefined];