Konrad Szydlo Blog: August 2013

In my first post I'll show you how to create a simple application in Grails that uses jQuery UI autocomplete and AJAX.

Project setup
Building Application:

creating domain class
creating controller
adding data via Bootstrap.groovy
creating view
modifying resource configuration
creating javascript file

Project setup

Create a new project - I called it GrailsAutocomplete

If we want to use jQuery UI autocomplete we can use jQuery UI Grails Plugin

Go to grails-app/conf/BuildConfig.groovy and in the plugins section paste jQuery UI dependency:
```
compile ":jquery-ui:1.8.24"  
```

Building Application

Creating domain class

create com.example.Country domain class

package com.example

    class Country {
    
        String name

        static constraints = {
            name(blank: false, unique: true)
        }
    }

Creating controller

create com.example.Country controller

       package com.example

      import grails.converters.JSON

      class CountryController {

   def scaffold = true

   def index() {
         redirect action: "autocomplete", params: params
   }

      def autocomplete() {
   params.max = Math.min(params.max ? params.int('max') : 10, 100)
             [countryInstanceList: Country.list(params), countryInstanceTotal: Country.count()]
      }

   def getAllCountries() {
         def countries = Country.list()
       def response = []

          countries.each {
              response << "${it.name}"
       }
      render response as JSON
      }
}

the index() method will redirect us to the autocomplete method
the autocomplete() method will get all the country instance saved in the DB and pass them as a list
by convention Grails will match the name of a method to a view with the same name; in a bit we will create our views/country/autocomplete.gsp
the getAllCountries() method retrieves a list of all countries from DB
we use each closure to populate the response list with the names of each Country instance
our return value is the response rendered as JSON
of course we don't have any country stored in the DB

Adding dummy data

conf/BootStrap.groovy is a good place where we can add some countries to our DB

import com.example.Country

class BootStrap {

    def init = { servletContext ->
        def poland = new Country(name: "Poland");
        poland.save(failOnError: true);

        def holland = new Country(name: "Holland");
        holland.save(failOnError: true);

        def uk = new Country(name: "United Kingdom");
        uk.save(failOnError: true);

        def uae = new Country(name: "United Arab Emirates");
        uae.save(failOnError: true);

        def honduras = new Country(name: "Honduras");
        honduras.save(failOnError: true);


    }
    def destroy = {
    }
}

Creating view

we can create now our views/country/autocomplete.gsp

<%@ page import="com.example.Country" %>
<!doctype html>
<html>
        <head>
                <meta name="layout" content="main">
                <g:set var="entityName" value="${message(code: 'country.label', default: 'Country')}" />
                <title><g:message code="default.list.label" args="[entityName]" /></title>
       <r:require module="jquery-ui"/>
                <g:javascript library="util"/>
        </head>
        <body>
                <a href="#list-country" class="skip" tabindex="-1"><g:message code="default.link.skip.label" default="Skip to content…"/></a>
                <div class="nav" role="navigation">
                        <ul>
                                <li><a class="home" href="${createLink(uri: '/')}"><g:message code="default.home.label"/></a></li>
                                <li><g:link class="create" action="create"><g:message code="default.new.label" args="[entityName]" /></g:link></li>
                        </ul>
                </div>
                <div id="list-country" class="content scaffold-list" role="main">

            <div>
                <h1 style="float: left;"><g:message code="default.list.label" args="[entityName]" /></h1><br/>
                <input style="float: right; margin: 0px 10px 10px 0px;" type="text" name="country" id="country_textField" value="" placeholder="Enter country..."/>
            </div>

                        <g:if test="${flash.message}">
                        <div class="message" role="status">${flash.message}</div>
                        </g:if>
                        <table>
                                <thead>
                                        <tr>

                                                <g:sortableColumn property="name" title="${message(code: 'country.name.label', default: 'Name')}" />

                                        </tr>
                                </thead>
                                <tbody>
                                <g:each in="${countryInstanceList}" status="i" var="countryInstance">
                                        <tr class="${(i % 2) == 0 ? 'even' : 'odd'}">

                                                <td><g:link action="show" id="${countryInstance.id}">${fieldValue(bean: countryInstance, field: "name")}</g:link></td>

                                        </tr>
                                </g:each>
                                </tbody>
                        </table>
                        <div class="pagination">
                                <g:paginate total="${countryInstanceTotal}" />
                        </div>
                </div>
        </body>
</html>

inside the head tag we have two important lines:

<r:require module="jquery-ui"/>
<g:javascript library="util"/>

r:require uses Grails resource plugin that will allow us to use jQuery UI on this page
g:javascript will import JS file called util
we have to tell Grails where to look for this file

Modifying resource configuration

go to conf/ApplicationResource.groovy and add reference to util resource
modules = {
    application {
        resource url:'js/application.js'
    }
    util {
       resource url:'js/util.js'
    }
}

Creating javascript file

now we can create a util.js file in web-app/js folder

$(document).ready(function() {
    $.ajax({
        type: "GET",
        url: "/GrailsAutocomplete/country/getAllCountries",
        success : function(response) {

            $("#country_textField").autocomplete({
                source: response
            });
        }
    });

});

we do an AJAX request to /GrailsAutocomplete/country/getAllCountries once we finish loading the html for the page
this URL will map to our Country controller and to it's method getAllCountries() that returns a JSON file with the names of the countries that are stored in the DB
we use this JSON to populate our autocomplete
note that the $(#country_textField) matches the id of our input from autocomplete.gsp

Running the app

Now we can run our app and go to:
http://localhost:8080/GrailsAutocomplete/country/

we should see a list of countries and an input box on the right-hand side
when you start typing 'ola' the list should be populated with 'Holand' and 'Poland'

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