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问题:
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?
回答1:
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($scope.life.meaning); // logs 42
回答2:
Using Erik's answer, as a starting point. I found a simpler solution that worked for me.
In my ng-click function I have:
var the_string = 'lifeMeaning';
if ($scope[the_string] === undefined) {
//Valid in my application for first usage
$scope[the_string] = true;
} else {
$scope[the_string] = !$scope[the_string];
}
//$scope.$apply
I've tested it with and without $scope.$apply. Works correctly without it!
回答3:
Create Dynamic angular variables from results
angular.forEach(results, function (value, key) {
if (key != null) {
$parse(key).assign($scope, value);
}
});
ps. don't forget to pass in the $parse attribute into your controller's function
回答4:
If you are ok with using Lodash, you can do the thing you wanted in one line using _.set():
_.set(object, path, value) Sets the property value of path on object. If a portion of path does not exist it’s created.
https://lodash.com/docs#set
So your example would simply be: _.set($scope, the_string, something);
回答5:
Just to add into alread given answers, the following worked for me:
HTML:
<div id="div{{$index+1}}" data-ng-show="val{{$index}}">
Where $index
is the loop index.
Javascript (where value
is the passed parameter to the function and it will be the value of $index
, current loop index):
var variable = "val"+value;
if ($scope[variable] === undefined)
{
$scope[variable] = true;
}else {
$scope[variable] = !$scope[variable];
}
回答6:
Please keep in mind: this is just a JavaScript thing and has nothing to do with Angular JS. So don't be confused about the magical '$' sign ;)
The main problem is that this is an hierarchical structure.
console.log($scope.life.meaning); // <-- Nope! This is undefined.
=> a.b.c
This is undefined because "$scope.life" is not existing but the term above want to solve "meaning".
A solution should be
var the_string = 'lifeMeaning';
$scope[the_string] = 42;
console.log($scope.lifeMeaning);
console.log($scope['lifeMeaning']);
or with a little more efford.
var the_string_level_one = 'life';
var the_string_level_two = the_string_level_one + '.meaning';
$scope[the_string_level_two ] = 42;
console.log($scope.life.meaning);
console.log($scope['the_string_level_two ']);
Since you can access a structural objecte with
var a = {};
a.b = "ab";
console.log(a.b === a['b']);
There are several good tutorials about this which guide you well through the fun with JavaScript.
There is something about the
$scope.$apply();
do...somthing...bla...bla
Go and search the web for 'angular $apply' and you will find information about the $apply function. And you should use is wisely more this way (if you are not alreay with a $apply phase).
$scope.$apply(function (){
do...somthing...bla...bla
})
回答7:
If you are using Lodash library below is the way to set a dynamic variable in the angular scope.
To set the value in the angular scope.
_.set($scope, the_string, 'life.meaning')
To get the value from the angular scope.
_.get($scope, 'life.meaning')
回答8:
If you were trying to do what I imagine you were trying to do, then you only have to treat scope like a regular JS object.
This is what I use for an API success response for JSON data array...
function(data){
$scope.subjects = [];
$.each(data, function(i,subject){
//Store array of data types
$scope.subjects.push(subject.name);
//Split data in to arrays
$scope[subject.name] = subject.data;
});
}
Now {{subjects}} will return an array of data subject names, and in my example there would be a scope attribute for {{jobs}}, {{customers}}, {{staff}}, etc. from $scope.jobs, $scope.customers, $scope.staff