通过实体框架将相关记录插入数据库

Question

I'm curious if there is a clean way to do this

Product product = new Product();
product.CreateDateTime = DateTime.Now;
product.Description = productCreateModel.Product.Description;
product.ManufacturerId = productCreateModel.Manufacturer;
product.MetaDescription = productCreateModel.Product.MetaDescription;
product.MetaTitle = productCreateModel.Product.MetaTitle;
product.Name = productCreateModel.Product.Name;
product.Status = ProductStatuses.Active;
product.URL = productCreateModel.Product.URL;

if (productCreateModel.ProductImage1.ContentLength > 0)
    {
        BinaryReader binaryReader = new BinaryReader(productCreateModel.ProductImage1.InputStream);
                product.ProductImages.Add(new ProductImage()
                {
                    CreateDateTime = DateTime.Now,
                    Image = binaryReader.ReadBytes(productCreateModel.ProductImage1.ContentLength),
                    PrimaryImage = true
                });
    }
db.Products.Add(product);
db.SaveChanges();

The problem i'm running into is that the product.ProductImages is null - I'd love to be able to do it this way INSTEAD of doing multiple db.TableName.Add/db.SaveChanges because if I understand it correctly EF creates a transaction so that if anything fails you won't have phantom product records inserted with no product images - if that makes sense?

Answer 1

change your Product Model ?

private IList<ProductImage> productImages_;
public virtual IList<ProductImage> ProductImages {
   get {
     return productImages_ ?? (productImages_= new List<ProductImage>());
   }
   set { productImages_ = value;}
}

Answer 2

I'm just brain storming here so don't get upset if this doesn't work, but I think you might need to explicitly add the new ProductImage entity to the db.ProductImages entity set before you link it to the Product entity.

Product product = new Product();
product.CreateDateTime = DateTime.Now;
product.Description = productCreateModel.Product.Description;
product.ManufacturerId = productCreateModel.Manufacturer;
product.MetaDescription = productCreateModel.Product.MetaDescription;
product.MetaTitle = productCreateModel.Product.MetaTitle;
product.Name = productCreateModel.Product.Name;
product.Status = ProductStatuses.Active;
product.URL = productCreateModel.Product.URL;

db.Products.Add(product);

if (productCreateModel.ProductImage1.ContentLength > 0)
    {
        BinaryReader binaryReader = new BinaryReader(productCreateModel.ProductImage1.InputStream);

        ProductImage image = new ProductImage()
        {
              CreateDateTime = DateTime.Now,
              Image = binaryReader.ReadBytes(productCreateModel.ProductImage1.ContentLength),
              PrimaryImage = true
        }

        db.ProductImages.Add(image); // Add the image to the ProductImage entity set
        product.ProductImages.Add(image); // link the image to this Product
    }

db.SaveChanges(); // Save all changes