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I have a string reference to one of my scope values like this:

var reference_string = "form.name";

And I want to assign a value to the object it is referencing:

$scope.form.name = 'newvalue';

Looking around, I found 2 possible solutions: using plain JS or using the angular $parse function.

However, it seems like the $parse function only returns the value. Can I make it so that I can assign a new value?

ie. I want to do something like

var reference_string = "form.name";
var reference = getReference($scope, reference_string); // ideally using an angular in-built function like $parse
reference = 'newvalue'; // should have the same effect as $scope.form.name = 'newvalue';
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xiankai
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  • Are you trying to use strings to access an object like `form['name']` ? – Tj Gienger Sep 14 '15 at 02:35
  • @TjGienger yeah, except that its in a nested format so I can't do it directly. `$scope['form.name']` won't work – xiankai Sep 14 '15 at 02:41
  • did you try `$scope['form']['name']` ? I never have, just a thought – Tj Gienger Sep 14 '15 at 02:43
  • use regex to separate the original string – Tj Gienger Sep 14 '15 at 02:43
  • @TjGienger Short of using eval, I can't do that. Also I mentioned that there was a plain JS way (through parsing the string and traversing the object), which is a little hacky and I was hoping for a more elegant solution with angular's `$parse`. – xiankai Sep 14 '15 at 02:48
  • This is definitely an XY question. Why are you trying to store the name of a variable as a string and then trying to reference it later in the first place? – Claies Sep 14 '15 at 03:26
  • @Claies I wouldn't necessarily say that. I've had to do similar to marry up server-side validation messages with scoped models. Sometimes all you have is a string reference. – Phil Sep 14 '15 at 03:38

2 Answers2

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The object returned by $parse has an assign() method for setting values.

var getter = $parse(reference_string);
getter.assign($scope, 'newValue');

Plunker demo ~ http://plnkr.co/edit/RlhXRpJvQ69ZdEkstyq8?p=preview

Phil
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  • Thanks! The example really helped to show how to use it. – xiankai Sep 14 '15 at 04:23
  • If the reference has multiple data {name1 : "test1",name2 : "test2"} How does it works with this scenario...@Phil – RJV Oct 19 '16 at 07:51
  • @VenkatRJV not sure what you mean. `$parse` only supports a single expression AFAIK but you can create multiple assignment strings for the same object – Phil Oct 19 '16 at 09:06
  • @Phil where did you get avatar like that? just curious :) – Rathma Nov 18 '17 at 10:18
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$parse is an Angular service which converts an expression into a function. The function can then be invoked and passed a context (usually scope) in order to retrieve the expression's value. In addition, if the expression is assignable the returned function will have an assign property. The assign property is a function that can be used to change the expression's value on the given context.

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PAWAN RAJ Shakya
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