[HttpPut("{id}")]
public async Task<object> EditEventOccurrence(int id, [FromBody] EventOccurrenceResource eventOccurrenceResource)
{
    if (!ModelState.IsValid)
        return BadRequest(ModelState);

    var eventOccurrence = await _context.EventOccurrences
        .Where(eo => eo.Id == id)
        .Include(eo => eo.DeviceOperation)
            .ThenInclude(devop => devop.Codes)
                .ThenInclude(co => co.Code)
            .Include(eo => eo.DeviceOperation)
                .ThenInclude(devop => devop.Breaker.SupplySubstation)
        .Include(eo => eo.Outage)
            .ThenInclude(o => o.Codes)
                .ThenInclude(co => co.Code)
            .Include(eo => eo.Outage)
                .ThenInclude(o => o.Substation)
        .SingleOrDefaultAsync();
    if (eventOccurrence == null)
    {
        return NotFound($"Event Occurrence {id} was not found");
    }

    _mapper.Map<EventOccurrenceResource, EventOccurrence>(eventOccurrenceResource, eventOccurrence);

    await _context.SaveChangesAsync();

    var result = _mapper.Map<EventOccurrence, EventOccurrenceResource>(eventOccurrence, eventOccurrenceResource);

    return Ok(result);
}

public class EventOccurrenceResource
{
    public int Id { get; set; }

    [Required]
    public int EventId { get; set; }
    public EventResource Event { get; set; }

    public DeviceOperationResource DeviceOperation { get; set; }

    public OutageResource Outage { get; set; }
}

public class EventOccurrence
{
    public int Id { get; set; }

    public Event Event { get; set; }
    public int EventId { get; set; }

    public DeviceOperation DeviceOperation { get; set; }
    public int? DeviceOperationId { get; set; }

    public Outage Outage { get; set; }
    public int? OutageId { get; set; }
}

CreateMap<EventOccurrenceResource, EventOccurrence>()
     .ForMember(eo => eo.Id, opt => opt.Ignore())
     .ForMember(eo => eo.OutageId, opt => opt.MapFrom(eor => eor.Outage.Id));