使用 ASP.NET Core 填充两个表数据

Question

我想在 ASP.NET Core 中获取两个表数据。我可以通过使用模型类来获得一个表格的详细信息。然后我可以使用下面的代码显示数据。

[HttpGet]
public async Task<ActionResult<IEnumerable<OrderMaster>>> GetOrderDetails()
{
    return await _context.OrderDetails.ToListAsync();
}

所以我的问题是如何获取两个表数据到上述方法？例如，我想检索以下查询的数据：

select a.ItemDescription,a.Quantity,a.Amount, a.CustomerCode, b.CustomerName,b.CustomerAddress,b.MobileNumber,b.Email from OrderDetails as a left join CustomerDetails as b ON a.CustomerCode=b.CustomerCode

谢谢

我的模型类

public class CustomerMaster
    {
        [Key]
        public int CustomerCode { get; set; }

        [Column(TypeName = "nvarchar(100)")]
        public string CustomerName { get; set; }

        [Column(TypeName = "nvarchar(100)")]
        public string CustomerAddress { get; set; }

        [Column(TypeName = "nvarchar(10)")]
        public string MobileNumber { get; set; }

        [Column(TypeName = "nvarchar(100)")]
        public string Email { get; set; }
    }

public class OrderMaster
    {
        [Key]
        public int OrderId { get; set; }

        [Column(TypeName = "nvarchar(100)")]
        public string ItemCode { get; set; }

        [Column(TypeName = "nvarchar(100)")]
        public string ItemName { get; set; }

        [Column(TypeName = "nvarchar(MAX)")]
        public string ItemDescription { get; set; }

        [Column(TypeName = "nvarchar(100)")]
        public string Quantity { get; set; }

        [Column(TypeName = "nvarchar(100)")]
        public string OrderDate { get; set; }

        [Column(TypeName = "nvarchar(100)")]
        public string Amount { get; set; }

        [Column(TypeName = "nvarchar(100)")]
        public string CustomerCode { get; set; }

    }

这是我的上下文类

public class AppDbcontext : DbContext
    {
        public AppDbcontext(DbContextOptions<AppDbcontext> options) : base(options)
        {
        }
        public DbSet<CustomerMaster> CustomerDetails { get; set; }
        public DbSet<OrderMaster> OrderDetails { get; set; }

        }
    }

Answer 1

关于如何连接两个表，你可以按照一个简单的演示：

var model = (from a in _context.CustomerDetails 
            join b in _context.OrderDetails 
            on a.ID equals b.ID
            select  new { 
                    Name = a.Name,
                    Address = b.Address
            }).ToList();

更新 1：

你使用左连接sql，你需要改变如下：

var model = (from a in _context.OrderDetails
                join b in _context.CustomerDetails
                on a.CustomerCode equals b.CustomerCode.ToString() into ab
                from b in ab.DefaultIfEmpty()
                select new
                {
                    ItemDescription = a.ItemDescription,
                    Quantity = a.Quantity,
                    Amount = a.Amount,
                    CustomerCode = a.CustomerCode,
                    CustomerName = b.CustomerName,
                    CustomerAddress = b.CustomerAddress,
                    MobileNumber = b.MobileNumber,
                    Email = b.Email,
                }).ToList();

更新 2：

关于如何返回两个表的数据，我觉得更好的方法是创建一个视图模型来展示：

public class OrderDetailViewModel
{
    public string ItemDescription { get; set; }
    public string Quantity { get; set; }
    public string Amount { get; set; }
    public string CustomerCode { get; set; }
    public string CustomerName { get; set; }
    public string CustomerAddress { get; set; }
    public string MobileNumber { get; set; }
    public string Email { get; set; }  
}
[HttpGet]
public IEnumerable<OrderDetailViewModel> GetOrderDetails()
{
    var model = (from a in _context.OrderDetails
                    join b in _context.CustomerDetails
                    on a.CustomerCode equals b.CustomerCode.ToString() into ab
                    from b in ab.DefaultIfEmpty()
                    select new OrderDetailViewModel
                    {
                        ItemDescription = a.ItemDescription,
                        Quantity = a.Quantity,
                        Amount = a.Amount,
                        CustomerCode = a.CustomerCode,
                        CustomerName = b.CustomerName,
                        CustomerAddress = b.CustomerAddress,
                        MobileNumber = b.MobileNumber,
                        Email = b.Email,
                    }).ToList();
    return model;
}

Answer 2

您必须通过导航属性连接两个模型。类似的东西

public class Table1 {
    int Table1Id;
    string Name;
    ICollection<Table2> Tables2;
}

public class Table2 {
    int Table2Id;
    string Address;
    Table1 Table1;
}

然后你就可以有你的业务层代码了

[HttpGet]
... GetNameWithAddresses(int id) {
    return (from c in _context.Table1 where c.Table1Id == id
        select new { c.Name, c.Tables2 }).ToList();
}

如果表有主外键关系，如果你脚手架它们会自动为你完成。如果你没有 FK 关系，你必须问问自己为什么！

Answer 3

使用此代码

using (var context = new AppDbcontext())
{
   var table1 = context.CustomerDetails.ToList();  
   var table2 = context.OrderDetails.ToList();  
}