ng-file-upload empty object on PUT request

Question

I'm working on a web-app where a feature is to open a file on the server through a webservice. I am working with Angular 1.5 and use ng-file-upload to upload all my files.

Here is the code I'm using:

Template:

<input type="file" ngf-select ng-model="temp_report.report" />

Controller:

// Temporary object which will store the File object
$scope.temp_report = {
    report: null
}

// Function called on click button
$scope.saveAuditorReport = function () {
    console.log($scope.temp_report.report);

    // Call to Service
    Audit.addAuditReport($scope.temp_report).then(
        function (resp) {
            console.log(resp);
        }, function (resp) {
            console.log(resp);
        }
    );
}

The console.log returns the File object. Everything is good.

And now, here is a part of the service:

this.addAuditReport = function (report) {
    console.log(report);
    return $http.put($rootScope.API_URL + '/audits/1/auditors/23928', {auditor: report});
}

The console.log is well returning the File object, so, everything is good too.

But on the PUT request, I don't understand anything. If I look the Chrome developer console, the sent request contains this:

auditor: {
    report: {}
}

My report object is now empty and I do not know what is happening. Does anyone have ever seen this?

Feel free to ask questions if I'm not giving every information I can. I will update them.