Grails Url Shortener

This is a grails plugin that integrates a url shortener inside your Grails application.

Installation

In BuildConfig add the following dependency:

compile ":url-shortener:<version>"

Configuration

After installing the plugin you have to add the following configuration to your Config.groovy file:

// Grails-url-shortener
shortener {
    characters = ('0'..'9') + ('a'..'h') + ('j'..'k') + ('m'..'z') + ('A'..'H') + ('J'..'K') + ('M'..'Z')
    minLength = 5
    shortDomain = http://YOUR-SHORT-DOMAIN.COM
}

characters the list of the valid characters for the shorted urls. In this example, the letters i, l, I, L are removed because they can be mix up with some typographies. You can create your custom list, for example, removing the vowels.
minLength is the minimum number of characters for the shorted url.
shortDomain the short domain for your url shortener.

Caution

If you include both lowercase and uppercase characters in the characters list you must make sure your database/table is configured to do case sensitive queries. Otherwise you could get the wrong URL back when querying the database.

Next you have to provide a unique number generator. The plugin provides an in-memory dummy implementation using AtomicLong available in the file DummySequenceGenerator.

Caution

Please do not use this default implementation for production because the counter is reset every time you start the app. You should only use this default implementation for develop o test environment.

To implement your custom unique number generator you have to create a simple Groovy or Java class that implements the net.kaleidos.shortener.SequenceGenerator interface. For example you can use a database sequence for this number generator. The following class use a Postgresql sequence for this:

/src/groovy/com/example/shortener/PostgresSequenceGenerator.groovy

package com.example.shortener

import net.kaleidos.shortener.SequenceGenerator
import groovy.sql.Sql

class PostgresSequenceGenerator implements SequenceGenerator {
    def dataSource

    Long getNextNumber() {
        def db = new Sql(dataSource)
        return db.rows("SELECT nextval('seq_shorten_url_generator')")[0]['nextval']
    }
}

Finally, when you have created you custom generator you have to define the sequenceGenerator bean in your resources.groovy file:

beans = {
    ...
    sequenceGenerator(com.example.shortener.PostgresSequenceGenerator) {
        dataSource = ref("dataSource")
    }
    ...
}

Sequence Generator Plugin

You can also use the sequence-generator plugin to generate sequence numbers for short urls. Version 1.1+ of sequence-generator is compatible with version 0.2+ of url-shortener. Just add the sequence-generator plugin to your BuildConfig.groovy and you are ready to go.

You don’t have to create a custom generator or configure a sequenceGenerator bean (section above), it done by the sequence-generator plugin.

Usage

The plugin provides a service urlShortenerService that you can inject into your grails artefacts with the following public methods:

shortUrl(String targetUrl): Returns a short url for the target url passed as param. If the url has already been shortened, the same short url is returned. Be careful because this method only returns the shortened characters for the target url but not the url with the configured short domain.
shortUrlFullDomain(String targetUrl): Returns the short url with the full domain.
getTargetUrl(String shortUrl): Returns the target url (original url) from the short url passed as param. The method also increase a counter with the number of times this url has been hit. If the short url does not exist the method return null.

Examples:

String shortUrl = urlShortenerService.shortUrl("http://kaleidos.net")
assert shortUrl.length() == 5

String shortUrlWithDomain = urlShortenerService.shortUrlFullDomain("http://kaleidos.net")
assert shortUrlWithDomain.length() > 5
assert shortUrlWithDomain.contains("http://") == true

String shortUrl = urlShortenerService.shortUrl("http://kaleidos.net")
assert urlShortenerService.getTargetUrl(shortUrl) == "http://kaleidos.net"

The plugin also provides a controller that can be used to redirect to the target url. It is available here ShortenerController or you can implement your own custom controller.

Tag Library

The plugin provides two GSP tags that generate short urls, link and createLink. They work as the standard Grails link and createLink but generates short urls.

function copyShortLinkToClipboard() {
    var url = "${shorter.createLink(controller: 'person', action: 'show', id: person.id, absolute: true)}";
    window.prompt("${message(code: 'copy.to.clipboard.label', 'Copy to clipboard: Ctrl+C, Enter')}", url);
}

Author

You can send any questions to:

Iván López: lopez.ivan@gmail.com (@ilopmar)

Collaborations are appreciated :-)

Release Notes

0.2.1 - 18/Jan/2015 - Fix regresion in 0.2 (See #6)
0.2 - 21/Nov/2014 - Added GSP tags shorter:link and shorter:createLink.
0.1 - 17/Oct/2013 - Initial version of the plugin.

goeh/grails-url-shortener