Returning a resolved resource in a service
I am new to writing services. I am calling a method on my factory that invokes a series of operations.
1) Get data from DB 2) Wait for $ prom to decide and then compare and filter the results 3) return a new filtered list
All I get when I go out of $ scope.new_list is an empty object. Can anyone help me with what I am doing wrong?
people.factory('uniqueContacts', ['apiResource', function(apiResource) {
function getDB() {
return apiResource.query({api_resource:'people'})
}
function generateList(newlistdata){
getDB().$promise.then(function(result){
newlist = _.difference(newlistdata, result);
})
return new_list;
});
}
return{
buildList: function(newlistdata){
return generateList(newlistdata);
}
}
}]);
//in my controller
$scope.new_list = uniqueContacts.buildList(newlistdata);
console.log($scope.new_list) // undefined
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3 answers
Because you are trying to output the asynchronous call synchronously, it does not output anything. Try this instead.
// Factory
people.factory('uniqueContacts', [
'apiResource',
function(apiResource) {
function getDB() {
return apiResource.query({api_resource:'people'})
}
function generateList(newlistdata){
return getDB().$promise.then(function(result){
// NOTE: You need to return the data you want the promise to
// resolve with.
return _.difference(newlistdata, result);
}, function (err) {
// TODO: Handle error
).catch(function (err) {
// TODO: Handle error that may have happened in the `then`.
// http://odetocode.com/blogs/scott/archive/2014/04/21/better-error-handling-in-angularjs.aspx
};
}
return {
// NOTE: There is no need to wrap `generateList` in an anonymous
// function when both take the same parameters, you can use the
// function definition directly.
buildList: generateList;
};
}
}]);
// Controller
// NOTE: `buildList` returns a promise that is asynchronously
// resolved/rejected. So in order to get the data returned you must
// use the `then` method.
uniqueContacts.buildList(newlistdata).then(function (list) {
$scope.newList = list;
console.log($scope.newList);
});
Literature:
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You should wait for a response (promise) to your request
function generateList(newlistdata){
getDB().$promise.then(function(result){
newlist = _.difference(newlistdata, result);
return new_list;
})
});
or if you want to handle the error:
function generateList(newlistdata){
getDB().$promise.then(function(result){
newlist = _.difference(newlistdata, result);
return new_list;
}, function(error) {
// TODO something when error
})
});
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