Singleton Pattern - wridgeu/wridgeu.github.io GitHub Wiki
To implement a singleton in UI5 you have to create a basic class. Instead of returning this class, you have to return a function that creates an instance of your Singleton class. This function will only make a new object/instance of the class the first time (if no instance/object exists). To know if an instance/object is already created, you can use a global variable to keep the active object/instance.
sap.ui.define([
"sap/ui/base/Object",
"some/Namespace/Folder/Person",
"some/Namespace/Folder/Skill"
], function(Object,Person,Skill) {
"use strict";
var instance;
var services = Object.extend("some.Namespace.Folder.Services", {
constructor:function(){
this.person = {};
this.skill = {};
},
setPerson:function(firstname,lastname){
this.person = new Person({firstname:firstname, lastname:lastname});
},
newSkill:function(skill){
this.person.addSkill(skill);
},
getInitialSkill:function(){
this.skill = new Skill({name:"name",value:"value"});
return this.skill;
}
});
return {
getInstance: function () {
if (!instance) {
instance = new services();
}
return instance;
}
};
});Usage of the singleton within the UI5 project:
services.getInstance();The function setPerson will create an object of the Person class. We can access all properties of the singleton instance as follows:
services.getInstance().personThe function newSkill will add a skill to the Person object and the function getInitialSkill will create an empty Skill object.