Reference Manual for Gracelets - Logo
2.10 - Tutorial : Using Actions Closures
The most common method expression/binding like closure you will use in Gracelets is most likely going to be action closures. These can replace the 'action' attribute of most of the UICommand based components, like the JSF Html CommandLink and CommandButton components.

Notice the following example:

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1 h.form { 
2     h.commandButton("Save Changes", action: {  
4         facesMessages.add("Your changes have been saved.") 
5     }) 
6 } 
These work just like normal method expressions/bindings. For instance, in regards to navigation, if you return a string from inside the closure, it will be used to do noraml JSF navigation. So if there is a navigation rule or case matching the outcome you return expect the navigation system to kick in.

Consider the following example:
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1 h.dataTable (value: { someDataModel }, var: "row") { 
2 ... 
3     h.column(facets: [header: { print "Options" }]) { 
4         h.commandLink(action: { selectedEntity = row; "someOutcome"; }) {  
5             h.graphicImage("images/editIcon.jpg") 
6         } 
7     } 
8 ... 
9 } 
Here we use an action closure to assign (or "outject") the selected record to the 'selectedEntity' context variable. Then we return a string that will be used to navigate to the page where the user could then edit the selected record.