angularjs restangular customPUT with Slim php restful framework - slim

Question

I am trying to update database using SLIM php. But the form data values passed in are showing blank. I have been successful in posting (customPOST) the values.
Here is the code:
AngularJs:
UpdateCategoryFormData:function(category,catId){
formData=new FormData();
angular.forEach(category, function (fieldData, field) {
formData.append(field, fieldData);
});
return Restangular.one('category/update',catId)
.withHttpConfig({transformRequest: angular.identity})
.customPUT(formData, undefined, {}, {'Content-Type': undefined});
}
SLIM php:
$app->put('/category/update/:catId',function($catId) use($app){
$data=$app->request->put();
print_r($data);
$catName=$app->request->put('catName');
$catParent=$app->request->put('catParent');
Result is:
array()
echo $catName;
I am getting a blank as the value of $catName;
Here is the copy of the headers:
Request Method:PUT
Status Code:200 OK
Response Headers
view source
Connection:Keep-Alive
Content-Length:10
Content-Type:text/html
Date:Fri, 28 Aug 2015 03:48:28 GMT
Keep-Alive:timeout=5, max=100
Server:Apache/2.4.9 (Win32) PHP/5.5.12
X-Powered-By:PHP/5.5.12
Request Headers
view source
Accept:application/json, text/plain, */*
Accept-Encoding:gzip, deflate, sdch
Accept-Language:en-US,en;q=0.8
Connection:keep-alive
Content-Length:249
Content-Type:multipart/form-data; boundary=----WebKitFormBoundary4gUX2gCt7zCICZNN
User-Agent:Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2489.0 Safari/537.36
Request Payload
------WebKitFormBoundary4gUX2gCt7zCICZNN
Content-Disposition: form-data; name="catName"
Some Category
------WebKitFormBoundary4gUX2gCt7zCICZNN
Content-Disposition: form-data; name="catParent"
45
------WebKitFormBoundary4gUX2gCt7zCICZNN--
Can someone help pls!