Added support for isLength assertion. (#14)

README.md

@@ -393,6 +393,7 @@ Here's a list of currently supported helpers:
 |isUUID(paramName [, version])| check if the string is a UUID (version 3, 4 or 5). |
 |matches(paramName, pattern [, modifiers])| check if string matches the pattern. Either `matches('foo', /foo/i)` or `matches('foo', 'foo', 'i')`. |
 |isPlainObject(paramName)| check if the current param is a plain object. |
+| isLength(paramName, options) | check if the string's length falls in a range. Note: this function takes into account surrogate pairs. |
 
 ### Not currently supported
 These are a few other helpers avaliable in [validator.js](https://github.com/chriso/validator.js) that could be used in property-validator.
@@ -417,7 +418,6 @@ Feel free to submit a PR if you need any of these functions.
 | isISBN(paramName [, version]) | check if the string is an ISBN (version 10 or 13). |
 | isISIN(paramName) | check if the string is an [ISIN][ISIN] (stock/security identifier). |
 | isISO8601(paramName) | check if the string is a valid [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) date. |
-| isLength(paramName, min [, max]) | check if the string's length falls in a range. Note: this function takes into account surrogate pairs. |
 | isLowercase(paramName) | check if the string is lowercase. |
 | isMACAddress(paramName) | check if the string is a MAC address. |
 | isMobilePhone(paramName, locale) | check if the string is a mobile phone number, (locale is one of `['zh-CN', 'zh-TW', 'en-ZA', 'en-AU', 'en-HK', 'pt-PT', 'fr-FR', 'el-GR', 'en-GB', 'en-US', 'en-ZM', 'ru-RU', 'nb-NO', 'nn-NO', 'vi-VN', 'en-NZ', 'en-IN']`). |

lib/validations.js

@@ -31,7 +31,7 @@ function checkParam(paramName, message, validator) {
     return {
       field: paramName,
       message: message,
-      result: validator.apply(null, [param + ""].concat(extraArgs))
+      result: (typeof param !== 'undefined') && validator.apply(null, [param + ""].concat(extraArgs))
     }
   }
 }
@@ -232,6 +232,19 @@ validations.isPlainObject = function isPlainObject(paramName, customMessage) {
   }
 }
 
+validations.isLength = validations.length = function isLength(paramName, options, customMessage) {
+  var errMessage = message(paramName, "length should be equals or greater then " + options.min + " and equals or less then " + options.max);
+  if (typeof options.min === 'undefined') errMessage = message(paramName, "length should be equals or less then " + options.max);
+  if (typeof options.max === 'undefined') errMessage = message(paramName, "length should be equals or greater then " + options.min);
+
+  return checkParam(
+    paramName,
+    customMessage || errMessage,
+    validator.isLength,
+    options
+  );
+}
+
 // TODO: Implement these validators
 //
 // isAfter(paramName [, date])
@@ -251,7 +264,6 @@ validations.isPlainObject = function isPlainObject(paramName, customMessage) {
 // isISBN(paramName [, version])
 // isISIN(paramName)
 // isISO8601(paramName)
-// isLength(paramName, min [, max])
 // isLowercase(paramName)
 // isMACAddress(paramName)
 // isMobilePhone(paramName, locale)

test/validation_test.js

@@ -337,4 +337,16 @@ describe('Validation Helpers', function() {
     f(v.isPlainObject('i')({ i: 'bla' }));
     m(v.isPlainObject('i')({ i: 'test' }), '"i" should be a plain object');
   });
+
+  it('isLength', function() {
+    t(v.isLength('i', {min: 9})({ i: 'something' }));
+    t(v.isLength('i', {max: 9})({ i: 'something' }));
+    t(v.isLength('i', {min: 9, max: 9})({ i: 'something' }));
+    f(v.isLength('i', {min: 10})({ i: 'something' }));
+    f(v.isLength('i', {max: 8})({ i: 'something' }));
+    f(v.isLength('i', {min: 10, max: 9})({ i: 'something' }));
+    m(v.isLength('i', {min: 10})({ i: 'something' }), '"i" length should be equals or greater then 10');
+    m(v.isLength('i', {max: 5})({ i: 'something' }), '"i" length should be equals or less then 5');
+    m(v.isLength('i', {min: 10, max: 5})({ i: 'something' }), '"i" length should be equals or greater then 10 and equals or less then 5');
+  })
 });