angular.js inject function into factory

Question

i have a function

function propValueFilter (toFilterArr, filterFunction) {
    return toFilterArr.filter(filterFunction);
};

and a factory

backpackrApp.factory('itemsFactory', function(propValueFilter) {

    factory.getBackpackById = function(id) {
    return backpacks.propValueFilter(function(element) {
        return element.id == id;
    });
};
return factory;
});

I am getting a Unknown Provider error in component $injector in the Webconsole.

How to inject a function right? I want to create a set of Helper functions which i can use in many controllers / factorys etc.

Thanks in Advance

Answer 1

You should wrap this function in another service/factory (named filterService in example below) and inject that into the items factory, like:

backpackrApp.factory('itemsFactory', ['filterService', function(filterService) {

factory.getBackpackById = function(id) {
return backpacks.propValueFilter(function(element) {
    return element.id == id;
});
};
return factory;
}]);

Answer 2

Spacing issue in the return of the 1st function? Should be:

function propValueFilter (toFilterArr, filterFunction) {
    return toFilterArr.filter(filterFunction);
};

Answer 3

I think you want to create helper functions you can inject them from a factory (assuming you know what you're doing with Array.filter):

backpackrApp.factory('myUtil', function() {
    var obj = {
        obj.propValueFilter = function(toFilterArr, filterFunction) {
            return toFilterArr.filter(filterFunction);
        };
    };
    return obj;
});

backpackrApp.factory('itemsFactory', function(myUtil) {
    var itemsFactoryObj = {
        backpacks = []; // set somewhere
        obj.getBackpackById = function(backpacks, id) {
            return myUtil.propValueFilter(function(element) {
                return element.id == id;
            });
        };
    };
    return itemsFactoryObj;
});

backpackrApp.controller('TestCtrl', function(itemsFactory) {
    $scope.backpack = itemsFactory.getBackpackById(1);
});