\n[ulp id=’kHqyxwGNoyzYAfPN’]<\/span><\/p>\n
Table Of Contents<\/h3>\n\n- 1. Development Environment Setup<\/a><\/dt>\n
- \n
\n- 1.1. JDK Install<\/a><\/dt>\n
- 1.2. Groovy Install<\/a><\/dt>\n
- 1.3. Grails Install<\/a><\/dt>\n
- 1.4. Environment Variables<\/a><\/dt>\n
- 1.5. Groovy\/Grails Tool Suite<\/a><\/dt>\n
- 1.6. Running First Application<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 2. MVC Structure<\/a><\/dt>\n
- 3. Controllers<\/a><\/dt>\n
- 4. Views<\/a><\/dt>\n
- \n
\n- 4.1. Groovy Server Pages<\/a><\/dt>\n
- 4.2. Layouts<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 5. Models and GORM<\/a><\/dt>\n
- \n
\n- 5.1. HQL Queries<\/a><\/dt>\n
- 5.2. Form Submission<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 6. Scaffolding<\/a><\/dt>\n
- 7. Application Service Layer<\/a><\/dt>\n
- 8. Conclusion<\/a><\/dt>\n<\/dl>\n<\/div>\n
<\/a>1. Development Environment Setup<\/h2>\nIn this section we will install JDK 8, Grails, Groovy\/Grails Tool Suite and make some environmental configurations to be able to use those tools. At the end, we will run our first sample application. By the way, I will proceed my installation with Mac OSX, and this means I will give you the clue here and you can find documentation about how to install it according to your operating system.<\/p>\n
<\/a>1.1. JDK Install<\/h3>\nSince Grails runs on JVM, we need to install JDK on our environment. Go to JDK download page here<\/a> and download JDK 8 according to your operating system and architecture. After download, you need to specify JAVA_HOME<\/code> environment variable as JDK home directory. You can also add $JAVA_HOME\/bin<\/code> path to your PATH<\/code> to run java on command line. Now, our environment knows how to use java, let’s continue with Grails installation<\/p>\n<\/a>1.2. Groovy Install<\/h3>\nIn order to install Groovy, you can go here<\/a> to download Groovy package.<\/p>\n![\"Groovy](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/11\/grails_on_groovy_2.jpg\")
<\/a>Groovy Download Page<\/figcaption><\/figure><\/p>\n<\/a>1.3. Grails Install<\/h3>\nGo to Grails download page here<\/a> and download latest Grails package.<\/p>\n![\"Grails](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/11\/grails_on_groovy_1.jpg\")
<\/a>Grails Download Page<\/figcaption><\/figure><\/p>\nAfter package download, extract the download content to folder you desired. We will use jdk and grails folders for environment variable setting.<\/p>\n
<\/a>1.4. Environment Variables<\/h3>\nWe have downloaded the JDK 8 and Grails, and the current version of JDK of mine is JDK 1.8.0_51<\/code> and Grails is 3.0.9<\/code>, lastly Groovy 2.4.5. So, you need to set following environment variables;<\/p>\nJAVA_HOME=\"\/path\/to\/jdk_1.8.0_51\"<\/code>
\nGROOVY_HOME=\"\/path\/to\/groovy-2.4.5\"<\/code>
\nGRAILS_HOME=\"\/path\/to\/grails-3.0.9\"<\/code><\/p>\nAlso, you need to add those home variables to the path if you want like below;<\/p>\n
PATH=$PATH:$JAVA_HOME\/bin<\/code>
\nPATH=$PATH:$GROOVY_HOME\/bin<\/code>
\nPATH=$PATH:$GRAILS_HOME\/bin<\/code><\/p>\nRemember that, all the environment settings above is Linux specific, you need to use os specific environment setting operation for your operating system.<\/p>\n
<\/a>1.5. Grails\/Groovy Tool Suite<\/h3>\nGroovy\/Grails Tool Suite is the most used IDE for Grails development. You can go grab from here<\/a>. After download, you can see executable inside ggts bundle folder and double click to open IDE. It will ask you the workspace before creating projects.<\/p>\n![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/11\/grails_on_groovy_3.jpg\")
<\/a>GGTS Workspace<\/figcaption><\/figure><\/p>\nNow, we need to be sure about GGTS knows your JRE and Grails installation. In order to check JRE configuration on GGTS, Go to Preferences<\/strong><\/p>\n![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/11\/grails_on_groovy_4.jpg\")
<\/a>GGTS Preferences<\/figcaption><\/figure><\/p>\nAnd then check Installed JREs<\/strong>. You need to see JRE path if you successfully defined JAVA_HOME<\/code>, if not, you need to point out installed JRE location.<\/p>\n![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_6.jpg\")
<\/a>GGTS Installed JREs<\/figcaption><\/figure><\/p>\nIt is same for Grails. Go to Preferences<\/strong> and then Grails<\/strong>. You need to point Grails installation location if it is not listed on the screen.<\/p>\n![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/11\/grails_on_groovy_6.jpg\")
<\/a>GGTS Grails<\/figcaption><\/figure><\/p>\nNow, we are able to create our first application.<\/p>\n
<\/a>1.6. Running First Application<\/h3>\nIn order to create Grails project, go to File > New > Grails Project<\/strong><\/p>\n![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_10.jpg\")
<\/a>GGTS New Project<\/figcaption><\/figure><\/p>\nProvide a name for new project and click Finish<\/strong> to create new project.<\/p>\n![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_11.jpg\")
<\/a>GGTS Project Name<\/figcaption><\/figure><\/p>\nYou will see a project structure like below after project creation.<\/p>\n
![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_12.jpg\")
<\/a>GGTS Project Structure<\/figcaption><\/figure><\/p>\nIn order to run application click run grails button in the toolbar like below.<\/p>\n
![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_13.jpg\")
<\/a>GGTS Run Project<\/figcaption><\/figure><\/p>\nYou will see a popup to execute specific task, enter run-app<\/strong> and click Enter<\/strong> to run project.<\/p>\n![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_14.jpg\")
<\/a>GGTS run-app task<\/figcaption><\/figure><\/p>\nNow you can see running project by going this url: http:\/\/localhost:8080\/HelloGrails<\/code>. The application is running on port 8080 and context path is same with name of your project name.<\/p>\n<\/a>2. MVC Structure<\/h2>\nNearly all of us know what is MVC pattern is, and Grails also uses MVC pattern to setup a basic web application in order to write clean code. Let’s have a look at MVC structure in Grails together.<\/p>\n
Model<\/strong> helps us to define our business model to handle data representation and handling. View<\/strong> is for showing data to end users. Controller<\/strong> helps us to transfer data between Model<\/strong> and View<\/strong>. By using those theoretical informations, we can proceed to some examples.<\/p>\nLet say that you have a model called User to handle user specific data. We can implement it like below.
<\/div> <\/div><\/p>\nUser.groovy<\/em><\/span><\/p>\nclass User {\n String name\n String email\n String password\n}\n<\/pre>\nIf you want to fetch some user data from datasource and display it on the view, you need to apply operation in controller section. Let say that it is like below.<\/p>\n
UserController.groovy<\/em><\/span><\/p>\nclass UserController {\n def list() {\n def userList = User.list()\n [userList:userList]\n }\n}\n<\/pre>\nHere we are simply getting the list of users through Customer<\/code> domain model to be able to use in controller. There is a naming convention in Grails that, whenever you go to \/user\/list<\/code> , list<\/code> method inside UserController<\/code> will be automatically be invoked. I mean that the pattern is;<\/p>\n{url_section_1}\/{url_section_2}<\/code> => {url_section_1}Controller.groovy<\/code> and {url_section_2}<\/code> action method. Also, the rendered view has a naming convention, in a way that it has same name with actions inside controllers. For example, when you go to \/user\/list<\/code>, list.gsp<\/code> automatically will be rendered. In controllers, we are passing model data to the views, so you can use following code to show model data to end users by make it rendered inside view layer.<\/p>\nlist.gsp<\/em><\/span><\/p>\n<ul>\n <g:each in=\"${userList}\" var=\"user\">\n\t<li>${user.name}, ${user.email}<\/li>\n <\/g:each>\n<\/ul>\n<\/pre>\nThis will render html something like below<\/p>\n
<ul>\n\t<li>John, john@gmail.com<\/li>\n<\/ul>\n<ul>\n\t<li>Doe, doe@gmail.com<\/li>\n<\/ul>\n<\/pre>\n<\/a>3. Controllers<\/h2>\nWe have already seen how a controller structure looks like, now let’s create a simple controller by using GGTS. Let say that, we want to create a controller in order to perform user related operations. In order to create a controller, Right-Click<\/strong> on project and New > Controller<\/strong> as below.<\/p>\n![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_15.jpg\")
<\/a>GGTS Create Controller<\/figcaption><\/figure><\/p>\nI assume you have provided controller name as UserController<\/code> and you will end up with following screen.<\/p>\n![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_16.jpg\")
<\/a>GGTS Sample Controller<\/figcaption><\/figure><\/p>\nWhen you look at screen, you can see that a default action called index()<\/code> created and also user related view folder is created in views<\/code> folder. Let say that, you want to display something when user go to default action of user controller. You can use following to do so.<\/p>\nUserController.groovy<\/em><\/span><\/p>\npackage hellograils\n\nclass UserController {\n\n def index() { \n\t\trender \"This is the index page of UserController\"\n\t}\n}\n<\/pre>\nWhen you go to http:\/\/localhost:8080\/HelloGrails\/user<\/code>, default action index()<\/code> will be executed and the text will be rendered on the browser by using render()<\/code> function.<\/p>\nLet’s do another example that whenever you go to user view action with a username provided in the url, it will be displayed on the page. In order to get url params in Grails, you can use params.key<\/code>. You can see full code to fetch username and display it on the page below.<\/p>\nUserController.groovy<\/em><\/span><\/p>\npackage hellograils\n\nclass UserController {\n\n def view() { \n\t\trender \"Hello, ${params.username}\"\n\t}\n}\n<\/pre>\nWhen you go to http:\/\/localhost:8080\/HelloGrails\/user\/view?username=huseyinbabal<\/code> you will see following.<\/p>\n![\"Grails](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_18.jpg\")
<\/a>Grails Url Params<\/figcaption><\/figure><\/p>\n<\/a>4. Views<\/h2>\nViews layer in a simple web application is used for the interaction with end user. You can use views to show your domain data after you have applied some rules inside your controller. In previous section we have created controller and it has automatically created specific view folder. We will use Groovy Server Pages to render and show your business data to end users in your Grails application.<\/p>\n
<\/a>4.1. Groovy Server Pages<\/h3>\nGroovy Server Pages (GSP) is the default template engine for the Grails. It is very simple and similar to JSP that allows you to show your data to user after rendered on server side. Let’s have a look at some examples for usage.<\/p>\n
If you want to show user related data on web page, you need a controller that we have already created in previous sections and you will need a specific view file. We have created an action called view() on UserController and let say that you want to display user data in view. You need to assign user model to view firs like below.<\/p>\n
UserController.groovy<\/em><\/span><\/p>\npackage hellograils\n\nclass UserController {\n\n def view() {\n def user = [name: \"John\", surname: \"Doe\", email: \"johndoe@gmail.com\"]\n\t [user: user]\n }\n}\n<\/pre>\nIn above code, we simply created a Groovy map for user properties and returned as map. In Groovy, the last line is returned by default. The key name returned in this function is user<\/code>, this means, you can access user data in the view by using user<\/code>. Since the action name is view<\/code>, we need to have a view file called view.gsp<\/code> in views > user<\/strong> folder. In order to create a GSP file, Right-Click<\/strong> on the project and New > Groovy Server Pages<\/strong> like below.<\/p>\n![\"GGTS](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_19.jpg\")
<\/a>GGTS Create GSP<\/figcaption><\/figure><\/p>\nAfter view file creation, add following gsp file content to view.gsp<\/code> file.<\/p>\nview.gsp<\/em><\/span><\/p>\n<!DOCTYPE html>\n<html>\n\t<head>\n\t\t<meta name=\"layout\" content=\"main\"\/>\n\t\t<title>User Profile<\/title>\n\t<\/head>\n\t<body>\n\t\t<table>\n\t\t\t<tr>\n\t\t\t\t<td>Name: <\/td><td>${user.name}<\/td>\n\t\t\t<\/tr>\n\t\t\t<tr>\n\t\t\t\t<td>Surname: <\/td><td>${user.surname}<\/td>\n\t\t\t<\/tr>\n\t\t\t<tr>\n\t\t\t\t<td>Email: <\/td><td>${user.email}<\/td>\n\t\t\t<\/tr>\n\t\t<\/table>\n\t<\/body>\n<\/html>\n<\/pre>\nIn this file, as you can see we have used user.{}<\/code> notation to access user related data passed from controller. Another important point in this view file is <\/code>. Here we are saying that, this file will be use the layout called main. And layout templates exists under views > layouts<\/strong> folder. When you go to http:\/\/localhost:8080\/HelloGrails\/user\/view<\/code>, you will see following screen.<\/p>\n
- \n
- 1.1. JDK Install<\/a><\/dt>\n
- 1.2. Groovy Install<\/a><\/dt>\n
- 1.3. Grails Install<\/a><\/dt>\n
- 1.4. Environment Variables<\/a><\/dt>\n
- 1.5. Groovy\/Grails Tool Suite<\/a><\/dt>\n
- 1.6. Running First Application<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 2. MVC Structure<\/a><\/dt>\n
- 3. Controllers<\/a><\/dt>\n
- 4. Views<\/a><\/dt>\n
- \n
- \n
- 4.1. Groovy Server Pages<\/a><\/dt>\n
- 4.2. Layouts<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 5. Models and GORM<\/a><\/dt>\n
- \n
- \n
- 5.1. HQL Queries<\/a><\/dt>\n
- 5.2. Form Submission<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 6. Scaffolding<\/a><\/dt>\n
- 7. Application Service Layer<\/a><\/dt>\n
- 8. Conclusion<\/a><\/dt>\n<\/dl>\n<\/div>\n
<\/a>1. Development Environment Setup<\/h2>\n
In this section we will install JDK 8, Grails, Groovy\/Grails Tool Suite and make some environmental configurations to be able to use those tools. At the end, we will run our first sample application. By the way, I will proceed my installation with Mac OSX, and this means I will give you the clue here and you can find documentation about how to install it according to your operating system.<\/p>\n
<\/a>1.1. JDK Install<\/h3>\n
Since Grails runs on JVM, we need to install JDK on our environment. Go to JDK download page here<\/a> and download JDK 8 according to your operating system and architecture. After download, you need to specify
JAVA_HOME<\/code> environment variable as JDK home directory. You can also add$JAVA_HOME\/bin<\/code> path to yourPATH<\/code> to run java on command line. Now, our environment knows how to use java, let’s continue with Grails installation<\/p>\n<\/a>1.2. Groovy Install<\/h3>\n
In order to install Groovy, you can go here<\/a> to download Groovy package.<\/p>\n
<\/a>Groovy Download Page<\/figcaption><\/figure><\/p>\n <\/a>1.3. Grails Install<\/h3>\n
Go to Grails download page here<\/a> and download latest Grails package.<\/p>\n
<\/a>Grails Download Page<\/figcaption><\/figure><\/p>\n After package download, extract the download content to folder you desired. We will use jdk and grails folders for environment variable setting.<\/p>\n
<\/a>1.4. Environment Variables<\/h3>\n
We have downloaded the JDK 8 and Grails, and the current version of JDK of mine is JDK
1.8.0_51<\/code> and Grails is3.0.9<\/code>, lastly Groovy 2.4.5. So, you need to set following environment variables;<\/p>\nJAVA_HOME=\"\/path\/to\/jdk_1.8.0_51\"<\/code>
\nGROOVY_HOME=\"\/path\/to\/groovy-2.4.5\"<\/code>
\nGRAILS_HOME=\"\/path\/to\/grails-3.0.9\"<\/code><\/p>\nAlso, you need to add those home variables to the path if you want like below;<\/p>\n
PATH=$PATH:$JAVA_HOME\/bin<\/code>
\nPATH=$PATH:$GROOVY_HOME\/bin<\/code>
\nPATH=$PATH:$GRAILS_HOME\/bin<\/code><\/p>\nRemember that, all the environment settings above is Linux specific, you need to use os specific environment setting operation for your operating system.<\/p>\n
<\/a>1.5. Grails\/Groovy Tool Suite<\/h3>\n
Groovy\/Grails Tool Suite is the most used IDE for Grails development. You can go grab from here<\/a>. After download, you can see executable inside ggts bundle folder and double click to open IDE. It will ask you the workspace before creating projects.<\/p>\n
<\/a>GGTS Workspace<\/figcaption><\/figure><\/p>\n Now, we need to be sure about GGTS knows your JRE and Grails installation. In order to check JRE configuration on GGTS, Go to Preferences<\/strong><\/p>\n
<\/a>GGTS Preferences<\/figcaption><\/figure><\/p>\n And then check Installed JREs<\/strong>. You need to see JRE path if you successfully defined
JAVA_HOME<\/code>, if not, you need to point out installed JRE location.<\/p>\n<\/a>GGTS Installed JREs<\/figcaption><\/figure><\/p>\n It is same for Grails. Go to Preferences<\/strong> and then Grails<\/strong>. You need to point Grails installation location if it is not listed on the screen.<\/p>\n
<\/a>GGTS Grails<\/figcaption><\/figure><\/p>\n Now, we are able to create our first application.<\/p>\n
<\/a>1.6. Running First Application<\/h3>\n
In order to create Grails project, go to File > New > Grails Project<\/strong><\/p>\n
<\/a>GGTS New Project<\/figcaption><\/figure><\/p>\n Provide a name for new project and click Finish<\/strong> to create new project.<\/p>\n
<\/a>GGTS Project Name<\/figcaption><\/figure><\/p>\n You will see a project structure like below after project creation.<\/p>\n
<\/a>GGTS Project Structure<\/figcaption><\/figure><\/p>\n In order to run application click run grails button in the toolbar like below.<\/p>\n
<\/a>GGTS Run Project<\/figcaption><\/figure><\/p>\n You will see a popup to execute specific task, enter run-app<\/strong> and click Enter<\/strong> to run project.<\/p>\n
<\/a>GGTS run-app task<\/figcaption><\/figure><\/p>\n Now you can see running project by going this url:
http:\/\/localhost:8080\/HelloGrails<\/code>. The application is running on port 8080 and context path is same with name of your project name.<\/p>\n<\/a>2. MVC Structure<\/h2>\n
Nearly all of us know what is MVC pattern is, and Grails also uses MVC pattern to setup a basic web application in order to write clean code. Let’s have a look at MVC structure in Grails together.<\/p>\n
Model<\/strong> helps us to define our business model to handle data representation and handling. View<\/strong> is for showing data to end users. Controller<\/strong> helps us to transfer data between Model<\/strong> and View<\/strong>. By using those theoretical informations, we can proceed to some examples.<\/p>\n
Let say that you have a model called User to handle user specific data. We can implement it like below.
<\/div> <\/div><\/p>\nUser.groovy<\/em><\/span><\/p>\n
class User {\n String name\n String email\n String password\n}\n<\/pre>\nIf you want to fetch some user data from datasource and display it on the view, you need to apply operation in controller section. Let say that it is like below.<\/p>\n
UserController.groovy<\/em><\/span><\/p>\n
class UserController {\n def list() {\n def userList = User.list()\n [userList:userList]\n }\n}\n<\/pre>\nHere we are simply getting the list of users through
Customer<\/code> domain model to be able to use in controller. There is a naming convention in Grails that, whenever you go to\/user\/list<\/code> ,list<\/code> method insideUserController<\/code> will be automatically be invoked. I mean that the pattern is;<\/p>\n{url_section_1}\/{url_section_2}<\/code> =>{url_section_1}Controller.groovy<\/code> and{url_section_2}<\/code> action method. Also, the rendered view has a naming convention, in a way that it has same name with actions inside controllers. For example, when you go to\/user\/list<\/code>,list.gsp<\/code> automatically will be rendered. In controllers, we are passing model data to the views, so you can use following code to show model data to end users by make it rendered inside view layer.<\/p>\nlist.gsp<\/em><\/span><\/p>\n
<ul>\n <g:each in=\"${userList}\" var=\"user\">\n\t<li>${user.name}, ${user.email}<\/li>\n <\/g:each>\n<\/ul>\n<\/pre>\nThis will render html something like below<\/p>\n
<ul>\n\t<li>John, john@gmail.com<\/li>\n<\/ul>\n<ul>\n\t<li>Doe, doe@gmail.com<\/li>\n<\/ul>\n<\/pre>\n
<\/a>3. Controllers<\/h2>\n
We have already seen how a controller structure looks like, now let’s create a simple controller by using GGTS. Let say that, we want to create a controller in order to perform user related operations. In order to create a controller, Right-Click<\/strong> on project and New > Controller<\/strong> as below.<\/p>\n
<\/a>GGTS Create Controller<\/figcaption><\/figure><\/p>\n I assume you have provided controller name as
UserController<\/code> and you will end up with following screen.<\/p>\n<\/a>GGTS Sample Controller<\/figcaption><\/figure><\/p>\n When you look at screen, you can see that a default action called
index()<\/code> created and also user related view folder is created inviews<\/code> folder. Let say that, you want to display something when user go to default action of user controller. You can use following to do so.<\/p>\nUserController.groovy<\/em><\/span><\/p>\n
package hellograils\n\nclass UserController {\n\n def index() { \n\t\trender \"This is the index page of UserController\"\n\t}\n}\n<\/pre>\nWhen you go to
http:\/\/localhost:8080\/HelloGrails\/user<\/code>, default actionindex()<\/code> will be executed and the text will be rendered on the browser by usingrender()<\/code> function.<\/p>\nLet’s do another example that whenever you go to user view action with a username provided in the url, it will be displayed on the page. In order to get url params in Grails, you can use
params.key<\/code>. You can see full code to fetch username and display it on the page below.<\/p>\nUserController.groovy<\/em><\/span><\/p>\n
package hellograils\n\nclass UserController {\n\n def view() { \n\t\trender \"Hello, ${params.username}\"\n\t}\n}\n<\/pre>\nWhen you go to
http:\/\/localhost:8080\/HelloGrails\/user\/view?username=huseyinbabal<\/code> you will see following.<\/p>\n<\/a>Grails Url Params<\/figcaption><\/figure><\/p>\n <\/a>4. Views<\/h2>\n
Views layer in a simple web application is used for the interaction with end user. You can use views to show your domain data after you have applied some rules inside your controller. In previous section we have created controller and it has automatically created specific view folder. We will use Groovy Server Pages to render and show your business data to end users in your Grails application.<\/p>\n
<\/a>4.1. Groovy Server Pages<\/h3>\n
Groovy Server Pages (GSP) is the default template engine for the Grails. It is very simple and similar to JSP that allows you to show your data to user after rendered on server side. Let’s have a look at some examples for usage.<\/p>\n
If you want to show user related data on web page, you need a controller that we have already created in previous sections and you will need a specific view file. We have created an action called view() on UserController and let say that you want to display user data in view. You need to assign user model to view firs like below.<\/p>\n
UserController.groovy<\/em><\/span><\/p>\n
package hellograils\n\nclass UserController {\n\n def view() {\n def user = [name: \"John\", surname: \"Doe\", email: \"johndoe@gmail.com\"]\n\t [user: user]\n }\n}\n<\/pre>\nIn above code, we simply created a Groovy map for user properties and returned as map. In Groovy, the last line is returned by default. The key name returned in this function is
user<\/code>, this means, you can access user data in the view by usinguser<\/code>. Since the action name isview<\/code>, we need to have a view file calledview.gsp<\/code> in views > user<\/strong> folder. In order to create a GSP file, Right-Click<\/strong> on the project and New > Groovy Server Pages<\/strong> like below.<\/p>\n<\/a>GGTS Create GSP<\/figcaption><\/figure><\/p>\n After view file creation, add following gsp file content to
view.gsp<\/code> file.<\/p>\nview.gsp<\/em><\/span><\/p>\n
<!DOCTYPE html>\n<html>\n\t<head>\n\t\t<meta name=\"layout\" content=\"main\"\/>\n\t\t<title>User Profile<\/title>\n\t<\/head>\n\t<body>\n\t\t<table>\n\t\t\t<tr>\n\t\t\t\t<td>Name: <\/td><td>${user.name}<\/td>\n\t\t\t<\/tr>\n\t\t\t<tr>\n\t\t\t\t<td>Surname: <\/td><td>${user.surname}<\/td>\n\t\t\t<\/tr>\n\t\t\t<tr>\n\t\t\t\t<td>Email: <\/td><td>${user.email}<\/td>\n\t\t\t<\/tr>\n\t\t<\/table>\n\t<\/body>\n<\/html>\n<\/pre>\nIn this file, as you can see we have used
user.{}<\/code> notation to access user related data passed from controller. Another important point in this view file is<\/code>. Here we are saying that, this file will be use the layout called main. And layout templates exists under views > layouts<\/strong> folder. When you go tohttp:\/\/localhost:8080\/HelloGrails\/user\/view<\/code>, you will see following screen.<\/p>\n - 5.2. Form Submission<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 4.2. Layouts<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 1.2. Groovy Install<\/a><\/dt>\n
![\"Grails](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_20.jpg\")
<\/a>![](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/12\/grails_on_groovy_21.jpg\"){kind=link}