Services Entity REST Application - Update (via put) Field Collection Data I am trying to figure out what the format and required parameters are for an update request to a field collection via the Services Module's REST API. I have installed the Services Entity API Module to allow interaction via Services with additional entity types.

I was able to save to a field collection when I first set everything up, using a PUT request, the CSRF token and properly formatted JSON.

{"field_fivestar_value":[
      {
         "rating":"100",
         "target":"0"
      }
   ]
}


which gave me this to access: field_fivestar_value['und'][0]['value'] which seemed to work perfect in the past, but now it seems that something is interfering/wrong as i get a notice after submitting a PUT request that $revision_id and/or $field_name aren't set, which never happened before...
It appears that something to do with revisions is causing the problem as if I provide specific (required?) data in my PUT request it works. Working PUT request JSON:

{
    "field_primary_aircraft": {
        "und": [
            {
                "value": "1"
            }
        ]
    },
    "field_name": "field_aircraft",
    "item_id": "5929",
    "revision_id": "5929",
    "default_revision": true,
    "field_aircraft_registration": {
        "und": [
            {
                "value": "testing12355"
            }
        ]
    }
}


That JSON plus a working CSRF token allowed me to save data back to a field collection that  is part of a users Profile2 profile.

The revision_id and default_revision were the trickiest parts to track down and supply, I don't have revisions enabled as far as I can tell also, so why this problem started suddenly I have no idea...at least it is solved and hopefully this info helps someone else.