Angular $http - function/response undefined - php

Question

I've been unable to retrieve data from a json or php file because angular keeps yelling at me that either the function or response is undefined.
I want to pull up the navigation items from MySQL, when it failed to load php I've put the contents in a regular json file to see what was the problem it seems something in angular itself.
PHP:
<?php
header('Content-type:application/json');
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "dbname";
$conn = mysqli_connect($servername, $username, $password, $dbname);
if (!$conn) {
die("Connection failed: " . mysqli_connect_error());
}
$sql = 'SELECT * FROM navigation';
$result = $conn->query($sql);
$emparray = array();
while($row = mysqli_fetch_assoc($result)) {
$emparray[] = $row;
}
echo json_encode($emparray);
$conn->close();
?>
Which results in:
[{"nav_id":"0","nav_name":"Home","nav_link":""}, {"nav_id":"1","nav_name":"Contact","nav_link":"contact"}]
So far so good?
Here's my angular code that gets the file:
(function() {
var app = angular.module("headerControl", []);
app.directive("headerNavigation", function() {
return {
retrict:'E',
templateUrl:'views/partials/header-navigation.html'
};
});
app.controller("navController", function($scope, $http) {
$scope.navlist = {};
$http.get('phpservices/nav.php')
.success(function(response) {
alert('success');
})
.error(alert('error'));
});
})();
When I load the page it first gives me the error response and after that the success response... in the console angular tells me this:
Error: [ng:areq] http://errors.angularjs.org/1.4.2/ng/areq?p0=fn&p1=not%20a%20function%2C%20got%20undefined
whats wrong about this? I can't seem to figure it out...

Answer 1

The problem is that you are not passing error callback function properly. It should be:
.error(function() {
alert('error')
});
Otherwise you just invoke alert immediately (note ()) and since it doesn't return anything (so it "returns" undefined) error handler receives undefined in it. However, it expects a function. That's why you get this error.