Difference between revisions of "VIATRA/Addon/Databinding"

// Step 7: combine everything, @PatternUI, @ObservableValue, @Handler
 
   /*
    * 
    * We want to find those years, which had courses taught by the busiest teacher
    * and included the most sociable students
    * 
    */
    @QueryExplorer(message="The busiest teacher $T.name$ taught the most sociable student $S.name$ in $Y.startingDate$")
    @ObservableValue(name = "Year", expression="Y.startingDate")
    @ObservableValue(name = "Teacher", expression="T.name")
    @ObservableValue(name = "Student", expression="S.name")
    @ObservableValue(name = "TeacherStudent", labelExpression = "Teacher $T.name$ teaches Student $S.name$")
    @Handler(fileExtension = "school")
    pattern finalPattern(Y:Year,C:Course,T:Teacher,S:Student) = {
    	Year.schoolClasses.courses(Y,C);
    	Course.teacher(C,T);
    	Student.schoolClass.courses(S,C);
 
    	find theOnesWithTheBiggestCircle(S);
    	find teachesTheMostCourses(T);
    }

@ObservableValue(name = "id", expression = "host.id")
@ObservableValue(name = "node_ip", expression = "host.nodeIp")
@ObservableValue(name = "current_cpu", expression = "host.availableCpu")
@ObservableValue(name = "current_hdd", expression = "host.availableHdd")
@ObservableValue(name = "current_ram", expression = "host.availableRam")
@ObservableValue(name = "total_cpu", expression = "host.totalCpu")
@ObservableValue(name = "total_hdd", expression = "host.totalHdd")
@ObservableValue(name = "total_ram", expression = "host.totalRam") 
pattern hostInstances(host: HostInstance) {
	HostInstance(host);
}
 
@ObservableValue(name = "id", expression = "app.id")
@ObservableValue(name = "state", expression = "app.state")
@ObservableValue(name = "db_user", expression = "app.dbUser")
@ObservableValue(name = "db_pass", expression = "app.dbPassword")
@ObservableValue(name = "allocatedTo", expression = "app.allocatedTo")
pattern applicationInstances(app: ApplicationInstance) {
	ApplicationInstance(app);
}

//Initialize VIATRA query engine
    	ViatraQueryEngine engine = ViatraQueryEngine.on(new EMFScope(resourceSet));
    	DataBindingPatterns.instance().prepare(engine);
 
    	//Get the matcher for the query to be observed (HostInstances pattern)
        HostInstancesMatcher matcher = HostInstancesMatcher.on(engine);
        //Create a generic databinding adapter for the query specification
        //It is responsible for creating observable value properties based on the annotations of the pattern
        //Bind the matches to the given TableViewer
        ViewerSupport.bind(
        		//Specify the target table viewer
                tableViewer,
                //Get the matching results as an observable list
                ViatraObservables.observeMatchesAsList(matcher),
                //Specify observed proeprties
                new IValueProperty[] { 
                		MatcherProperties.getValueProperty(HostInstancesMatcher.querySpecification(), "id"),
                		MatcherProperties.getValueProperty(HostInstancesMatcher.querySpecification(),"node_ip"),
                		MatcherProperties.getValueProperty(HostInstancesMatcher.querySpecification(),"current_cpu"),
                		MatcherProperties.getValueProperty(HostInstancesMatcher.querySpecification(),"current_hdd"),
                		MatcherProperties.getValueProperty(HostInstancesMatcher.querySpecification(),"current_ram"),
                		MatcherProperties.getValueProperty(HostInstancesMatcher.querySpecification(),"total_cpu"),
                		MatcherProperties.getValueProperty(HostInstancesMatcher.querySpecification(),"total_hdd"),
                		MatcherProperties.getValueProperty(HostInstancesMatcher.querySpecification(),"total_ram") });

//Create new data binding context
//It will be used for binding the pattern match details
DataBindingContext dataBindingContext = new DataBindingContext();
//Initialize VIATRA query engine
ViatraQueryEngine engine = ViatraQueryEngine.on(new EMFScope(resourceSet));
//Prepare target patterns
DataBindingPatterns.instance().prepare(engine);
//Get the matcher for the query to be observed (ApplicationInstances pattern)
ApplicationInstancesMatcher matcher = ApplicationInstancesMatcher.on(engine);
// Create a generic databinding adapter for the query specification
// It is responsible for creating observable value properties based on
// the annotations of the pattern
//Bind the matches to the given ListViewer
ViewerSupport.bind(listViewer, ViatraObservables.observeMatchesAsSet(matcher), MatcherProperties.getValueProperty(ApplicationInstancesMatcher.querySpecification(), "id"));
 
//At this point, the results of the given pattern will appear in the list Viewer, the details however still need to be implemented
//Define target observable values for both textboxes
IObservableValue dbUserTarget = WidgetProperties.text().observe(dbUser);
IObservableValue dbPassTarget = WidgetProperties.text().observe(dbPass);
 
//Observe the changes in the list selection        
IViewerObservableValue listSelection = ViewerProperties
	.singleSelection().observe(listViewer);
 
//Use the data binding context to bind the text property of the target textbox and the given property of the matcher.   
dataBindingContext.bindValue(
		//Target textbox observable value
		dbPassTarget, 
		//Get the source observable value from the adapter
		MatcherProperties.getValueProperty(ApplicationInstancesMatcher.querySpecification(), "db_pass").observeDetail(listSelection), 
		//Define EMF update value strategy
	    //In this case its one directional
		new EMFUpdateValueStrategy(UpdateValueStrategy.POLICY_NEVER),
		new EMFUpdateValueStrategy());
 
dataBindingContext.bindValue(dbUserTarget, adapter.getProperty("db_user").observeDetail(listSelection), 
	new EMFUpdateValueStrategy(UpdateValueStrategy.POLICY_NEVER),
	new EMFUpdateValueStrategy());