从ASP DotNet Core中的父实体更新多个子实体

Question

我在更新父实体时一直在尝试更新子实体。但这是行不通的。这是我的父母（寄售）模型。

 public class Consignment
{
    public Guid Id { get; set; }
    public DateTime? DateCreated { get; set; }
    public DateTime? DateModified { get; set; }
    public Guid AccountId { get; set; }
    ...
    ...
    public Guid BookedByUser { get; set; }
    public Guid? ModifiedByUser { get; set; }
    public string DescriptionToLeave { get; set; }
    public Account account{ get; set; }
    public User bookedbyUserNavigation { get; set; }
    public User quotedbyUserNavigation { get; set; }
    public ICollection<ConsignmentLine> consignmentLine { get; set; }
    public ICollection<Legging> leg { get; set; }
}

子实体是consignmentLine和Legging。它们如下：

public class ConsignmentLine
{
    public Guid Id { get; set; }
    public string ItemName { get; set; }
    ...
    public bool? Deleted { get; set; }
    public Guid? ConsignmentId { get; set; }
    public Guid? ItemId { get; set; }
    public Guid? CommodityId { get; set; }
    public string CommodityName { get; set; }

您可以看到consignmentLine具有父实体Consignment和ItemCommodity。绑腿是：

public class Legging
{
    public Guid Id { get; set; }
    public DateTime? DateCreated { get; set; }
    ...
    public string ToLeg { get; set; }
    public Guid? CarrierAccount { get; set; }
    public Guid? ConsignmentId { get; set; }
    public string CarrierName { get; set; }
}

我已经在我的PUT寄售控制器中编写了这段代码。

[HttpPut]
    public async Task<IActionResult> PutConsignment(Consignment consignment)
    {
        var existingcon = _context.Consignment
            .Include(cl => cl.ConsignmentLine)
            .Include(l => l.Legging)
            .Include(sc => sc.SenderContactNavigation)
            .Include(rc => rc.ReceiverContactNavigation)
            .Include(sa => sa.SenderAddressNavigation)
            .Include(ra => ra.ReceiverAddressNavigation)
            .Include(bu => bu.BookedByUserNavigation)
            .Include(cu => cu.CheckedByUserNavigation)
            .SingleOrDefault(c => c.Id == consignment.Id);
        if (existingcon.Id != consignment.Id)
        {
            return BadRequest();
        }

        //update consignment
        var newcon = _context.Entry(existingcon);
        newcon.CurrentValues.SetValues(consignment);

        //update or add consignmentLine

        foreach (var conline in consignment.ConsignmentLine)
        {
            var line = existingcon.ConsignmentLine
                .Where(x => x.Id == conline.Id)
                .SingleOrDefault();
            if (line != null)
            {
                var l = _context.Entry(line);
                l.CurrentValues.SetValues(line);
            }
            else
                existingcon.ConsignmentLine.Add(conline);
        }
        //remove consignmentline
        foreach (var line in existingcon.ConsignmentLine.Where(x=> x.Id !=null).ToList())
        {
            if(!consignment.ConsignmentLine.Any(x=> x.Id == line.Id))
            {
                _context.ConsignmentLine.Remove(line);
            }
        }

        //add or update Legging
        foreach (var newleg in consignment.Legging)
        {
            var leg = existingcon.Legging
                .Where(x => x.Id == newleg.Id)
                .SingleOrDefault();

            if (leg != null)
            {
                var le = _context.Entry(leg);
                le.CurrentValues.SetValues(leg);
            }
            else
                existingcon.Legging.Add(leg);
        }
        //remove legs
        foreach (var leg in existingcon.Legging.Where(x=> x.Id !=null).ToList())
        {
            if(!consignment.Legging.Any(x=> x.Id == leg.Id))
            {
                _context.Legging.Remove(leg);
            }
        }

        try
        {

            await _context.SaveChangesAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            if (!ConsignmentExists(consignment.Id))
            {
                return NotFound();
            }
            else
            {
                throw;
            }
        }

        return Ok(consignment);
    }

[当我尝试更新现有托运货物时，它在绑腿时抛出Null异常，但对consignmentLine来说效果很好。知道为什么吗？

Answer 1

实际上，代码将是：

    [HttpPut]
    public async Task<IActionResult> PutConsignment(Consignment consignment)
    {
        var existingcon = _context.Consignment
            .Include(cl => cl.ConsignmentLine)
            .Include(l => l.Legging)
            .Include(sc => sc.SenderContactNavigation)
            .Include(rc => rc.ReceiverContactNavigation)
            .Include(sa => sa.SenderAddressNavigation)
            .Include(ra => ra.ReceiverAddressNavigation)
            .Include(bu => bu.BookedByUserNavigation)
            .Include(cu => cu.CheckedByUserNavigation)
            .SingleOrDefault(c => c.Id == consignment.Id);
        if (existingcon.Id != consignment.Id)
        {
            return BadRequest();
        }

        //update consignment
        var newcon = _context.Entry(existingcon);
        newcon.CurrentValues.SetValues(consignment);

        //update or add consignmentLine

        foreach (var conline in consignment.ConsignmentLine)
        {
            var line = existingcon.ConsignmentLine
                .Where(x => x.Id == conline.Id)
                .SingleOrDefault();
            if (line != null)
            {
                var l = _context.Entry(line);
                l.CurrentValues.SetValues(line);
            }
            else
                existingcon.ConsignmentLine.Add(conline);
        }
        //remove consignmentline
        foreach (var line in existingcon.ConsignmentLine.Where(x=> x.Id !=null).ToList())
        {
            if(!consignment.ConsignmentLine.Any(x=> x.Id == line.Id))
            {
                _context.ConsignmentLine.Remove(line);
            }
        }

        //add or update Legging

        foreach (var newleg in consignment.Legging)
        {
            var leg = existingcon.Legging
                .Where(x => x.Id == newleg.Id)
                .SingleOrDefault();

            if (leg != null)
            {
                var le = _context.Entry(leg);
                le.CurrentValues.SetValues(leg);
            }
            else
                existingcon.Legging.Add(newleg);
        }
        //remove legs
        foreach (var leg in existingcon.Legging.Where(x=> x.Id !=null).ToList())
        {
            if(!consignment.Legging.Any(x=> x.Id == leg.Id))
            {
                _context.Legging.Remove(leg);
            }
        }

        try
        {
            await _context.SaveChangesAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            if (!ConsignmentExists(consignment.Id))
            {
                return NotFound();
            }
            else
            {
                throw;
            }
        }

        return Ok(consignment);
    }