Im using Entity framework to manage a postgresql database, which has three tables–Products, ProductCategories and ProductImages, these three tables are related to each other through foreign key,for example the ‘ProductCategoryId” of Products table is a foreign key to the “ProductCategories” table, so do the “ProductImageId” which is a foreigh key to the “ProductImages” table.
Here is the data seeding class

public static class DbInitializer
    {
        public static void Initialize(ProductContext context)
        {

            if (context.Products.Any()
            && context.ProductCategories.Any()
            && context.ProductImages.Any())
            {
                return;   // DB has been seeded
            }


            var productCategories = new ProductCategory[]
              {
                new ProductCategory
                    {
        
                        Name = "Tops",
                    },
                new ProductCategory
                    {
                        
                        Name = "Hats",
                    },
                new ProductCategory
                    {
                        Name = "Shoes",
                    },
               //...
          };
         

            //seeding productImages 
            var productImages = new ProductImage[]
                {
                new ProductImage
                    {
                        // Id = 1,
                        Name = "cat-photo_0000.jpg",
                        Description="Wings harness"
                    },
                new ProductImage
                    {
                        // Id = 2,
                        Name = "cat-photo_0001.jpg",
                        Description="Carry Bag Deluxe"
                    },
                 
            };

            //seeding Products
            var products = new Product[]
            {
                new Product
                    {
                        Name = "Angel Wings Harness",
                        Description = "The purrrfect accessory to take your kitty to the next level.",
                        Price = 10,
                  
                    },
                new Product
                    {
                        Name = "Deluxe Carry Bag Orange",
                        Description = "Backpack-style carry bag with dome.",
                        Price = 20,
                       
                    },
             
            };

         

         context.Products.AddRange(products);
         context.ProductCategories.AddRange(productCategories);
         context.ProductImages.AddRange(productImages);

        context.SaveChanges();
        }


    }

Here are the three entities–Product,ProductCategories and ProductImages

{

    public class Product
    {
        // [Key]
        // public int Id { get; set; }
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int Id { get; set; }

        [Required]
        public string? Name { get; set; }

        public string? Description { get; set; }

        [Column(TypeName = "money")]
        public decimal Price { get; set; }

        [ForeignKey("ProductCategory")]
        public int? ProductCategoryId { get; set; }
        public ProductCategory? ProductCategory { get; set; }

        [ForeignKey("ProductImage")]
        public int? ProductImageId { get; set; }
        public ProductImage? ProductImage { get; set; }
    }


}



public class ProductCategory
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int Id { get; set; }

        [Required]
        [MaxLength(100)] // Adjust the maximum length as needed
        public string Name { get; set; }
    }




public class ProductImage
{
    // [Key]
    // public int Id { get; set; }
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [Required]
    [MaxLength(100)] // Adjust the maximum length as needed
    public string? Name { get; set; }

    [MaxLength(500)] // Adjust the maximum length for description
    public string? Description { get; set; }
}

I have seeded some dummy data in the three tables, as you can see the “ProductCategoryId” and “ProductImageId” columns got no values(null) in the “Products” table

After that, I can post new records from the swagger page for example.

Now my question is, how can I populate those “Id” values from “ProductCategories” and “ProductImages” table and apply them into the “Products” table to replace thos NULL values? Looks like a silly question but just need some helps. Thank you.