AngularJS: global access to services?
<p>I've got a simple setup, but I'm probably not "thinking like a JS programmer."  There are multiple controllers, for different pages, that all call a routine for ajaxing to PHP.  Simplified version below.  It's working, but I'm obviously not setting it up correctly, since I've got to pass all these service objects through to every single call...How should this be set up?</p>

<pre><code>app.controller('ctrlA', $scope, $http, $location, $sce) {
    app.db_read($scope, $http, {param: 1}, $sce, 
         function() {// succeeded},
         function() {// failed}
    )
}

app.controller('ctrlB', $scope, $http, $location, $sce) {
    app.db_read($scope, $http, {param: 1}, $sce, 
         function() {// succeeded},
         function() {// failed}
    )
}
...
app.db_read = function($scope, $http, payload, $location, $sce) {
    $http.post('url', {request: 'read', data: payload})
         .then(function(data) {$scope.data = data},
         function(error) {$scope.displayError = $sce.trustAsHtml(error)}
    )
}
</code></pre>

<p>I looked at this question: <a href="https://stackoverflow.com/questions/26498649/instantiate-global-services-in-angularjs">Instantiate global services in AngularJS</a>
...where the answer appears as, "Services are singletons in Angular, so you should just inject them where ever you need them."
Unfortunately, I don't know how to "inject" a service into my db_read function.  Thank you for your help.</p>