how to dynamically add observer methods to an Ember.js object
11,391
I don't know your exact use case, but as you said, your described problem could be solved with a Mixin, see http://jsfiddle.net/pangratz666/a3Usx/
JavaScript:
App = Ember.Application.create();
var methodsToDefine = [
{checkerName: "standoutHolderChecked", methodToCall: "toggleParentStandout"},
{checkerName: "holderPaddingChecked", methodToCall: "toggleParentPadding"},
{checkerName: "holderMarginChecked", methodToCall: "toggleParentMargin"}
];
App.Stalker = Ember.Mixin.create({
init: function() {
this._super();
methodsToDefine.forEach(function(config) {
// add an observer for checkerName - a change should call methodToCall
Ember.addObserver(this, config.checkerName, this, config.methodToCall);
}, this);
},
willDestroy: function() {
this._super();
// since we are good citizens, we remove the observers when the object is destroyed
methodsToDefine.forEach(function(config) {
Ember.removeObserver(this, config.checkerName, this, config.methodToCall);
}, this);
}
});
Sample use case:
var myObj = Ember.Object.create(App.Stalker, {
toggleParentStandout: function() {
console.log("toggleParentStandout called");
},
toggleParentPadding: function() {
console.log("toggleParentPadding called");
},
toggleParentMargin: function() {
console.log("toggleParentMargin called");
}
});
myObj.set('standoutHolderChecked', 42);
myObj.set('holderPaddingChecked', 'Buster');
Another implementation would be a mixin which uses an array watchProperties
, which is a list of properties which shall be observed, see http://jsfiddle.net/pangratz666/bSF3Z/:
JavaScript:
App = Em.Application.create();
App.Stalker = Ember.Mixin.create({
init: function() {
this._super();
var props = this.get('watchProperties');
Ember.assert("watchProperties should be an array", Ember.isArray(props));
props.forEach(function(property) {
// invoke <property>Changed when <property> changes ...
Ember.addObserver(this, property, this, '%@Changed'.fmt(property));
}, this);
},
willDestroy: function() {
this._super();
this.get('watchProperties').forEach(function(property) {
Ember.removeObserver(this, property, this, '%@Changed'.fmt(property));
}, this);
}
});
var o = Ember.Object.create(App.Stalker, {
// 'a b'.w() == ['a', 'b']
watchProperties: 'a b'.w(),
aChanged: function() {
console.log("a changed");
}
});
o.set('a', 123);
Author by
Rick Moss
Updated on June 17, 2022Comments
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Rick Moss almost 2 years
So i am trying to dynamically add these observer methods to a Ember.js object
holderStandoutCheckedChanged: (-> if @get("controller.parent.isLoaded") @get("controller").toggleParentStandout(@get("standoutHolderChecked")) ).observes("standoutHolderChecked") holderPaddingCheckedChanged: (-> if @get("controller.parent.isLoaded") @get("controller").toggleParentPadding(@get("holderPaddingChecked")) ).observes("holderPaddingChecked") holderMarginCheckedChanged: (-> if @get("controller.parent.isLoaded") @get("controller").toggleParentMargin(@get("holderMarginChecked")) ).observes("holderMarginChecked")
I have this code so far but the item.methodToCall function is not getting called
methodsToDefine = [ {checkerName: "standoutHolderChecked", methodToCall: "toggleParentStandout"}, {checkerName: "holderPaddingChecked", methodToCall: "toggleParentPadding"}, {checkerName: "holderMarginChecked", methodToCall: "toggleParentMargin"} ] add_this = { } for item in methodsToDefine add_this["#{item.checkerName}Changed"] = (-> if @get("controller.parent.isLoaded") @get("controller")[item.methodToCall](@get(item.checkerName)) ).observes(item.checkerName) App.ColumnSetupView.reopen add_this
Can anyone tell me what i am doing wrong ? Is there a better way to do this ? Should i be doing this in a mixin ? If so please
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jrode about 9 yearsthis solves so many problems for me, thanks. was trying to figure out how to observe
[email protected]
without having to loop through the array to find out what changed. this allows me to do a kind of proxying that lets dynamic form field objects communicate with a very different looking model.