member="'e' |lambda: 'e.name'"
You can do this with something like (I wrote this just for the question, what I do in my apps is outlined below)
app.filter('lambda', [
'$parse',
function ($parse) {
return function (lambdaArgs, lambdaExpression, scope) {
var parsed = $parse(lambdaExpression);
var split = lambdaArgs.split(',');
var result = function () {
var args = {};
angular.extend(args, scope || {});
for (var i = 0; i < arguments.length && i < split.length; i++) {
args[split[i]] = arguments[i];
}
return parsed(args);
};
return result;
}
}
]);
Advanced usage:
(x, y, z) => x * y * z + a // a is defined on scope
'x,y,z' |lambda: 'x * y * z + a':this
The :this
will pass the scope along to the lambda so it can see variables there, too. You could also pass in an aliased controller if you prefer. Note that you can also stick filters inside the first argument to the lambda
filter, like:
('x'|lambda:'x | currency')(123.45) // $123.45 assuming en-US locale
HOWEVER I have thus far avoided a lambda filter in my apps by the following:
The first approach I've taken to deal with that is to use lodash-like filters.
So if I have an array of objects and your case and I want to do names, I might do:
myArray | pluck:'name'
Where pluck
is a filter that looks like:
angular.module('...', [
]).filter('pluck', [
function () {
return function (collection, property) {
if (collection === undefined) {
return;
}
try {
return _.pluck(collection, property);
} catch (e) {
}
}
}
]);
I've implemented contains
, every
, first
, keys
, last
, pluck
, range
(used like [] | range:6
for [0,1,2,3,4,5]
), some
, and values
. You can do a lot with just those by chaining them. In all instances. I literally just wrapped the lodash library.
The second approach I've taken is to define functions inside a controller, expose them on the scope.
So in your example I'd have my controller do something like:
$scope.selectName = function (item) { return item.name };
And then have the directive accept an expression - &
- and pass selectName
to the expression and call the expression as a function in the directive. This is probably what the Angular team would recommend, since in-lining in the view is not easily unit-test-able (which is probably why they didn't implement lambdas). (I don't really like this, though, as sometimes (like in your case) it's strictly a presentation-thing - not a functionality-thing and should be tested in an E2E/Boundary test, not a unit test. I disagree that every little thing should be unit tested as that often times results in architecture that is (overly) complicated (imho), and E2E tests will catch the same thing. So I do not recommend this route, personally, though again I think the team would.)
3.
The third approach I've taken would be to have the directive in question accept a property-name as a string. I have an orderableList
directive that does just that.