www.example.com核心中的多对多污垢操作asp.net

4dc9hkyq 于 2022-12-20 发布在 .NET

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我有两个具有多对多关系的实体（Product和Supply），在它们之间还有一个实体，它拥有两个ID（SupplyProduct）。
我的实体：

public class Product
    {
        [Key]
        public int ProductId { get; set; }
        [Required]
        public string? ProductName { get; set; }
        [Required]

        [Column(TypeName = "decimal(6,2)")]
        public decimal UnitPrice { get; set; }
        public int Quantity { get; set; }
        public string? Brand { get; set; }
        public DateTime CreatedDateTime { get; set; } = DateTime.Now;

        //Many to many relationship between the products and the stocks
        public virtual ICollection<SupplyProduct>? SupplyProducts { get; set; }
    }

    public class Supply
    {
        [Key]
        [Required]
        public int SupplyId { get; set; }
        [Required]

        [DisplayName("Supply's Label")]
        public string? Label { get; set; }
        
        //One to many relationship between the Stock and the Merchant
        public Merchant? Merchant { get; set; }

        //Many to many relationship between the stocks and the products
        public virtual ICollection<SupplyProduct>? SupplyProducts { get; set; }

    }

    public class SupplyProduct
    {
        [Key]
        public int SupplyId { get; set; }
        public virtual Supply? Supply { get; set; }
        [Key]
        public int ProductId { get; set; }
        public virtual Product? Product { get; set; }
    }

我想在创建产品时将供应分配给产品。然后显示供应及其关联产品

这是我的产品控制器：
ProductsController.cs

public class ProductController : Controller
    {
        private readonly ApplicationDbContext _db;

        public ProductController(ApplicationDbContext db)
        {
            _db = db;
        }

        // GET: ProductController
        public ActionResult Index()
        {
            IEnumerable<Product> ProductsList = _db.Products;
            return View(ProductsList);
        }

        // GET: ProductController/Create
        public ActionResult Create()
        {
            IEnumerable<Supply> SuppliesList = _db.Supplies.Include(s => s.Merchant);
            ViewBag.Supplies = SuppliesList;
            return View();
        }

        // POST: ProductController/Create
        [HttpPost]
        public ActionResult Create(Product model, List<int> supplyIds)
        {
            _db.Products.Add(model);
            _db.SaveChanges();
            
            SupplyProduct SP = new();
            foreach (var supplyId in supplyIds)
            {
                SP.SupplyId = supplyId;
                SP.ProductId = model.ProductId;
                SP.Product = model;
                SP.Supply = _db.Supplies.Where(x => x.SupplyId == supplyId).FirstOrDefault();
            }
            _db.SupplyProducts.Add(SP);
            _db.SaveChanges();
            return RedirectToAction(nameof(Index));
        }
}

请检查我的postCreate方法是否正确，以及如何在Index方法中将Supplies返回到索引视图时获取Products数据？
非常感谢您的帮助和快乐的编码：D

asp.net

来源：https://stackoverflow.com/questions/74841868/many-to-many-crud-operations-in-asp-net-core

2条答案

按热度按时间

ohfgkhjo1#

如果除了SupplyProduct之外没有其他属性，您可以删除SupplyProduct表，因为多对多不需要它。

public class Product
{
    public Product()
    {
        this.Supplys = new HashSet<Supply>();
    }

    //... your props

    public virtual ICollection<Supply> Supplys { get; set; }
}

public class Supply
{
    public Supply()
    {
        this.Products = new HashSet<Product>();
    }

    //... your props

    public virtual ICollection<Product> Products { get; set; }
}

只需一次查询即可将产品添加到供应（在代码中，您查询supplyIds中的每个人ID）

[HttpPost]
public ActionResult Create(Product model, List<int> supplyIds)
{
     //Get all supplys you need by id
     var supplys = _db.Supplys
         .Where(x => supplyIds.Contains(x.SupplyId))
         .ToList();
     
     //Add product in each supply
     foreach (var supply in supplys)
     {
         supply.Products.Add(model);
     }

     //Update db
     _db.SaveChanges();

     return RedirectToAction(nameof(Index));
}

从数据库获取

public ActionResult GetSuplys(List<int> supplyIds)
{
     //Here you get all Supplys with the Products in it
     var supplys = _db.Supplys
         .Include(x => x.Products)
         .Where(x => supplyIds.Contains(x.SupplyId))
         .ToList();

     //...
}

保存新产品供应

public ActionResult NewSuply()
{

     var supply = new Supply
     {
        ProductName = name,
        //Add all props you need
        //You can add Product here or add empty collection
        Products.Add(product), or = new List<Product>();
     }
     
     //No need to save Product separate
     _db.Add(supply);
     _db.SaveChanges();
}

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wlzqhblo2#

你可以请检查我的职位创建方法，如果它是因为它应该是
按如下所示修改代码，否则第二个电源将始终存储在supplyIds中：

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create(Product model, List<int> supplyIds)
{
    _context.Product.Add(model);
    _context.SaveChanges();

    SupplyProduct SP = new();
    foreach (var supplyId in supplyIds)
    {
        SP.SupplyId = supplyId;
        SP.ProductId = model.ProductId;
        SP.Product = model;
        SP.Supply = _context.Supply.Where(x => x.SupplyId == supplyId).FirstOrDefault();
        _context.SupplyProducts.Add(SP);   //move to here...
        _context.SaveChanges();
    }
    // _context.SupplyProducts.Add(SP);
    //_context.SaveChanges();
    return RedirectToAction(nameof(Index));
}

如何在将Index方法中的Supplies返回到索引视图时获取Products数据？
更改您的索引方法如下：

// GET: Products
public async Task<IActionResult> Index()
{
    var data = await _context.Product.Include(p => p.SupplyProducts)
                             .ThenInclude(sp => sp.Supply).ToListAsync();
    return View(data);
}

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www.example.com核心中的多对多污垢操作asp.net

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