Response to give for partially successful post to Web API - asp.net

Question

What is the best response to give, if a number of objects are sent to my web api controller, to be inserted into my database, where some may be successful, and some may fail? A normal HTTP response I don't think will suffice - would it be better to find some way of returning a JSON string of what has been successful, and what has not? If so, how would I do that?
My Post controller is shown below.
Thanks for any help,
Mark
public HttpResponseMessage PostBooking(Booking[] bookings)
{
if (ModelState.IsValid)
{
foreach (var booking in bookings)
{
// check if there are any bookings already with this HID and RID...
var checkbooking = db.Bookings.Where(h => h.HID == booking.HID && h.RID == booking.RID).ToList();
// If so, return a response of conflict
if (checkbooking.Count != 0 || checkbooking.Any())
{
throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.Conflict));
}
else
{
// If not add the booking to the database and return a response of Created
db.Bookings.Add(booking);
db.SaveChanges();
}
}
HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.Created);
return response;
}
else
{
// Model is not valid, so return BadRquest
return Request.CreateResponse(HttpStatusCode.BadRequest);
}
}

Answer 1

You could return a JSON list containing the ids of the objects that failed to be inserted:
{
"failedIds": [
4,
7,
9
]
}
500 HTTP response status code also seems appropriate as the request didn't complete successfully.
You could even bring that a step further and provide an explanation why insertion failed for each particular id:
{
"failed": [
{
"id": 4,
"reason": "database unavailable"
},
{
"id": 7,
"reason": "network cable unplugged"
},
{
"id": 9,
"reason": "a thief is currently running away with our server"
}
]
}