Forked from mudassir0909/ember_unknown_property_hook.js
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August 29, 2015 14:17
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| // Little background about unknown properties | |
| var myObject = Ember.Object.create({name: 'hi'}); # a plain simple ember object | |
| // so the property "name" is a known property for myObject, but any other properties which are not defined on this object are unknown properties | |
| myObject.get("age"); // age is an unknown property as we did not set "age" yet, the expression on the left evaluates to undefined | |
| // Be careful ! only properties on the object that are not "set" yet are unknown properties but not the properties that evaluate to null/undefined | |
| myObject.set("status", undefined); // although myObject.get("status") evaulates to undefined, status is a known property for myObject | |
| // unknownProperty hook | |
| // Basically when we do a "get" on a unknown property, instead of returning undefined the result of the unknownProperty hook is returned | |
| var hookedObject = Ember.Object.create({ | |
| name: 'hi', | |
| unknownProperty: function(key) { | |
| return key+" is an unknown property"; | |
| } | |
| }); | |
| hookedObject.get("name"); // => hi | |
| hookedObject.get("randomKey"); // => randomKey is an unknown property | |
| hookedObject.get("age"; // => age is an unknown property | |
| hookedObject.set("age", 22); // age is now a known property | |
| hookedObject.get("age"); // => 22 | |
| // setUnknownProperty hook | |
| // it gets called when we are trying to do a set on an unknown property | |
| var baseObject = Ember.Object.create(); | |
| var hookedObject = Ember.Object.create({ | |
| setUnknownProperty: function(key, value){ | |
| baseObject.set(key, value); | |
| } | |
| }); | |
| hookedObject.set("name", "Bruce"); | |
| baseObject.get("name"); // => Bruce | |
| // We are basically proxying the set property to other object, Reminds you of something ?...Enter Ember.ObjectProxy | |
| // `Ember.ObjectProxy` forwards all properties not defined by the proxy itself | |
| // to a proxied `content` object. (from the source code) | |
| // Let's implement a similar proxy object of our own using the above concepts | |
| var myProxyObject = Ember.Object.create({ | |
| unknownProperty: function(key){ | |
| var content = this.get("content"); | |
| if(content){ | |
| return content.get(key); | |
| } | |
| }, | |
| setUnknownProperty: function(key, value){ | |
| var content = this.get("content"); | |
| if(content){ | |
| return content.set(key, value); | |
| }else{ | |
| // raise an error saying cannot set key, value as the content property is undefined | |
| } | |
| } | |
| }) |
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