UrlWithoutSchemeValidator Grails Plugin

Summary

The Url Without Scheme Validator Plugin allows to use custom validator that validates the URLs but - different than standard validator - does not care if the scheme (ex. http, ftp) is provided or not. Moreover, it can be used like "first-class", built-in validator.

Instalation

Add the following to your grails-app/conf/BuildConfig.groovy

…
plugins {
…
	 compile ':url-without-scheme-validator:0.3'
…
}

Description

Purpose

It's a common requirement to save the URL a user provides. The standard Grails validatior accepts only URLs with scheme, like

http://www.google.com

But users often provide the URL without scheme, ie.

www.google.com

The goal of this plugin is to provide a URL validator that allows you to validate the URL, no matter if the scheme was provided or not.

Usage

The plugin can be used the same way as built-in domain-level validators, like url: true, blank: false, etc.

So to make sure the URL is valid, no matter if user put the scheme or not, just use urlWithoutScheme: true.

Example:

package com.example

class Domain {

	String url

	static constraints = {
	    url urlWithoutScheme: true
	}

}

Retrieving valid URL (with scheme)

The validator allows users to save URLs without scheme, which is perfect for displaying. However, the URL without scheme is not usable in, for example, HTML A tag:

<a href="www.google.com">Google</a> // not a proper URL

That's why the plugin contains the util method that prefix the given URL with scheme, but only if it is necessary. Otherwise, it returns the input as it is. The method has the following signature:

String prefixSchemeIfNecessary(final String url, final UrlScheme scheme = HTTP)

The default scheme is UrlScheme.HTTP, but UrlScheme.HTTPS and UrlScheme.FTP are also available.

The example usage could look like:

package com.example

class Domain {

	static transients = ['httpUrl', 'ftpUrl']

	String url

	static constraints = {
	    url nullable: true, urlWithoutScheme: true
	}

	String getHttpUrl() {
		UrlValidatorUtils.prefixSchemeIfNecessary(url) // prefixes url with http scheme, if no scheme is provided
	}

	String getFtpUrl() {
		UrlValidatorUtils.prefixSchemeIfNecessary(url, UrlScheme.FTP) // prefixes url with ftp scheme, if no scheme is provided
	}

}

Internationalization (i18n)

The default error message for the validator is

default.url.without.schema.not.valid.message=Property [{0}] of class [{1}] with value [{2}] is not a valid URL

It's also possible to configure it on a field level, by creating an entry in messages.properties with suffix:

not.urlWithoutScheme

So the message.properties entry for the class above could look like:

com.example.Domain.url.not.urlWithoutScheme={2} is not a valid URL

And result in error message saying for example:

     www.googlewww.invalidtld is not a valid URL (.google is valid since version 0.3 (like .beer, .vodka and .pizza)