Setting dynamic scope variables in AngularJs - scope.<some_string>

Erik Honn picture Erik Honn · Sep 18, 2013 · Viewed 122.6k times · Source

I have a string I have gotten from a routeParam or a directive attribute or whatever, and I want to create a variable on the scope based on this. So:

$scope.<the_string> = "something".

However, if the string contains one or more dots I want to split it and actually "drill down" into the scope. So 'foo.bar' should become $scope.foo.bar. This means that the simple version won't work!

// This will not work as assigning variables like this will not "drill down"
// It will assign to a variables named the exact string, dots and all.
var the_string = 'life.meaning';
$scope[the_string] = 42;
console.log($scope.life.meaning);  // <-- Nope! This is undefined.
console.log($scope['life.meaning']);  // <-- It is in here instead!

When reading a variable based on a string you can get this behavior by doing $scope.$eval(the_string), but how to do it when assigning a value?

Answer

Erik Honn picture Erik Honn · Sep 18, 2013

The solution I have found is to use $parse.

"Converts Angular expression into a function."

If anyone has a better one please add a new answer to the question!

Here is the example:

var the_string = 'life.meaning';

// Get the model
var model = $parse(the_string);

// Assigns a value to it
model.assign($scope, 42);

// Apply it to the scope
// $scope.$apply(); <- According to comments, this is no longer needed

console.log($scope.life.meaning);  // logs 42