feat(select): New select attribute directive ng:hasher

[quazzie]

Add new attribute directive for specifying a hashing function for objects.
If ng:model is bound to an object and ng:options is "obj for obj in objs"
a reference equality is used for selection.
With ng:hasher you can bind a function that takes one argument and returns
a hash. Then the hash is used for comparision instead.

Ex.
<select ng-model="selection" ng-options="obj for obj in objs" ng-hasher="hash_func"> /select>

scope: {
  selection: { id: 12, ... },
  objs: [{ id: 12, ... }, { id: 13, ... }],
  hash_func: function(o) {
    return o ? o.id : undefined;
  }
}

Will match model to the first obj in the objs array.

[gonzaloruizdevilla]

Yesterday I needed this functionality, and this would make my code much cleaner and simple 👍
@quazzie You should check code indenting between lines 433 and 443

[mhevery]

This change can be achieved by:

scope.hash_func = function() {};

ng-model="selection"
ng-options="hash_func(obj) for obj in objs">

So the new behavior just introduces a new way to do the same thing. For this reason we will not merge it in. If you feel otherwise feel free to reopen it and provide counter argument.

[quazzie]

@mhevery : no it is not the same. It will not run the hasher function on the selection/ng-model object, it will not select the object with id 12.

I don't know how to reopen this, i'm a noob git user.

[ProLoser]

What is wrong with object.id as object.label?

[quazzie]

Maybe a better example:

$scope.person = { id:1, name:'Thomas', favorite_movie: { id:2, name: 'Startrek' } };
$scope.movies = [{ id: 1, name: 'Starwars' }, { id: 2, name: 'Startrek' }, { id: 3, name: 'Alien' }];

Without the hashing function i have to:

<select ng-model="movieid" ng-options="movie.id as movie.name for movie in movies"></select>

$scope.movieid = $scope.person.favorite_movie.id;
$scope.$watch('movieid', function() {
  for(var i = 0; i < $scope.movies.length; i++)
    if ($scope.movies[i].id == $scope.movieid)
       $scope.person.favorite_movie = $scope.movies[i];
});

With the hashing function i could just write :

<select ng-model="person.favorite_movie" ng-options="movie as movie.name for movie in movies" ng-hasher="moviehasher"></select>

$scope.moviehasher = function(movie) { return movie ? movie.id : undefined; }

[ProLoser]

What about ng-options="index as movie.name for (index, movie) in movies" and simply retrieve the row you need when necessary (rather than setting up a watch).

I may not be clear on what you wanted but if I understand correctly, I only foresee a plethora of problems with this design:

• You must ALWAYS set the value to an ID
• Changing a property of the object may be considered a re-selection?
• You are setting the model to an ID and it immediately changes to a model inexplicably

It feels like it would create an unreliable and inconsistent behavior.

Dean Sofer
DeanSofer.com
714.900.2254

On Thursday, January 17, 2013 at 1:29 PM, quazzie wrote:

Maybe a better example:
$scope.person = { id:1, name:'Thomas', favorite_movie: { id:2, name: 'Startrek' } }; $scope.movies = [{ id: 1, name: 'Starwars' }, { id: 2, name: 'Startrek' }, { id: 3, name: 'Alien' }];

Without the hashing function i have to:

$scope.movieid = $scope.person.favorite_movie.id; $scope.$watch('movieid', function() { for(var i = 0; i < $scope.movies.length; i++) if ($scope.movies[i].id == $scope.movieid) $scope.person.favorite_movie = $scope.movies[i]; });

With the hashing function i could just write :

$scope.moviehasher = function(movie) { return movie ? movie.id : undefined; }

—
Reply to this email directly or view it on GitHub (#1663 (comment)).

[petebacondarwin]

How about just changing select to use a deep compare rather than object equality? This would solve many problems that people have with selecting an object rather than an object's id. In the case of the example above:

$scope.person = { id:1, name:'Thomas', favorite_movie: { id:2, name: 'Startrek' } };
$scope.movies = [{ id: 1, name: 'Starwars' }, { id: 2, name: 'Startrek' }, { id: 3, name: 'Alien' }];

This would just work:

<select ng-model="person.favorite_movie" ng-options="movie as movie.name for movie in movies" ></select>

As long as the properties on the person.favorite_movie matched the properties on an object in the movies array.

[quazzie]

Yeah what @petebacondarwin said is what i wanted, but i thought i'd be a bit more clever to allow for more configuration.
With the hasher function i can control what gets compared.

[quazzie]

@ProLoser

• the hashing function can return anything comparable.
• changing a property that is included in the hashing should re-select.
• i don't want to set model to an id, i want to set it to a model/object.

The hashing function should be used with objects. If options is value-types hashing would be unnecessary.

[wagnerfrancisco]

Im having the same problem. This functionality would be very interesting.

[quazzie]

I wrote another patch that does the same thing but in a diffrent way : #2040