Asp.Net Core中包含数据的多个图像保存

如何解决Asp.Net Core中包含数据的多个图像保存

我正在尝试保存一条记录以及多张图像。 Order类具有Images，这是orderImage类的iCollection，我要在其中保存每条记录的图像。

public class Order
{
    [Key]
    public int Id { get; set; }

    [Display(Name = "Invoice ID")]
    public string InvoiceId { get; set; }

    [Display(Name = "Delivery Date")]
    public string DeliveryDate { get; set; }

    [Display(Name = "Shipping Location")]
    public int ShippingLocationId { get; set; }

    [Display(Name = "Branch ID")]
    public string BranchId { get; set; }

    [Display(Name = "Product Name")]
    public string ProductName { get; set; }

    [Display(Name = "Product Color")]
    public string ProductColor { get; set; }

    [Display(Name = "Product Size")]
    public string ProductSize { get; set; }

    [Display(Name = "Quantity")]
    public string Quantity { get; set; }

    [Display(Name = "Status")]
    public string OrderStatusId { get; set; }

    [Display(Name = "Sales Consultant")]
    public string SalesPersonId { get; set; }

    [Display(Name = "Order Note")]
    public string OrderNote { get; set; }

    [Display(Name = "Delivery Note")]
    public string DeliveryNote { get; set; }

    public ICollection<OrderImage> Images { set; get; }
}

public class OrderImage
{
    [Key]
    public int Id { set; get; }
    public string Name { set; get; }
    public long Size { set; get; }
    public string Type { set; get; }
    public string Path { set; get; }
    public int orderId { set; get; }
}

然后将图像保存在具有orderID的其他表中，以便可以识别。 控制器在下面。

[HttpPost]
        public async Task<IActionResult> NewOrderAsync(Order _order,IFormFile[] _fileObj,OrderImage _orderImage)
        {
            if (_fileObj == null || _fileObj.Length == 0)
            {
                ViewData["NullImage"] = "Please select at least one Image";
            }
            foreach (IFormFile _image in _fileObj)
            {
                string _imageExtension = Path.GetExtension(_image.FileName);
                if (_imageExtension == ".jpg" || _imageExtension == ".png" || _imageExtension == ".JPEG" || _imageExtension == ".webp")
                {
                    var _imageFileName = _order.InvoiceId + "_" + _image.FileName;
                    var _imageSave = Path.Combine(_iWebHost.WebRootPath,"OrderImage");
                    var _stream = new FileStream(Path.Combine(_imageSave,_imageFileName),FileMode.Create);

                    await _image.CopyToAsync(_stream);

                    _orderImage.Name = _imageFileName;
                    _orderImage.Type = _imageExtension;
                    _orderImage.Path = _imageSave;
                    _orderImage.Size = _image.Length;
                    _orderImage.orderId = _order.Id;

                    await _context.OrderImage.AddAsync(_orderImage);
                    ViewData["Message"] = "Image is saved";
                }
                else
                {
                    ViewData["Message"] = "Image is not saved";
                }
            }
        _context.Add(_order);
        await _context.SaveChangesAsync();
        return RedirectToAction("Order");
        }

我遇到的问题是，无论何时保存图像，我都能够保存订单记录和上载图片的最后一张图像。根据数据库，当涉及到OrderID为0时，我尝试调试。订单ID返回0。如果我的操作方法正确，我确实需要建议。对于order和orderImages，有两个表。

解决方法

使用导航属性。订单可以具有图像集合和/或图像可以具有对订单的引用。当使用“标识”键列设置实体（应作为标准）时，EF将没有要提供的PK值，除非您调用SaveChanges（）。导航属性是允许EF将提供的FK推迟到保存整个对象图的关键。

作为一个简单的例子：

public class Order
{
    [Key]
    public int OrderId { get; set; }
    // Other Order fields...
    public virtual ICollection OrderImage Images { get; set; } = new List<OrderImage>();
}

public class OrderImage
{
    [Key]
    public int OrderImageId { get; set; }
    [ForeignKey("Order")]
    public int OrderId { get; set; }
    public virtual Order Order { get; set; }
}

然后当您去填充新订单和图像时：

var order = new Order
{
   // populate fields...
}

foreach (var file in files)
{
    var orderImage = new OrderImage
    {
        // copy details from file...
        Order = order
    }
    order.Images.Add(orderImage);
}

context.Orders.Add(order);
context.SaveChanges();

由于EF知道Order和OrderImages之间的导航属性关系，所以当您插入新的Order和一组Image时，EF将自动在图像上计算出FK OrderId，以确保先保存Order，并为其分配新的ID，然后将OrderId提供给图像。

我强烈建议您阅读EF中的导航属性，因为这些属性使EF不必担心写作和阅读中的FK关系。