在一对多关系中使用 Entity Framework Core 从 ASP.NET Core 中的三个相关表加载数据导致某些数据不显示

Question

我有三个 table Customer、Loan 和 LoanHistories。 Customertable与Loantable是一对多关系，Loantable与[=18有关=] 在一对多关系中也是如此。

以下是这些 table 的 C# 类：

public class Customer
{
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    [Display(Name = "ID NO")]
    public int CustomerID { get; set; }
    [Display(Name = "First Name")]
    public string FirstName { get; set; }
    [Display(Name = "Last Name")]
    public string LastName { get; set; }
    [Display(Name = "Phone Number")]
    public string PhoneNo { get; set; }
    [Display(Name = "Nearest Primary School")]
    public string NearestPrimarySchool { get; set; }
    [Display(Name = "Photo")]
    public string Photo { get; set; }

    public ICollection<Loan> loans { get; set; }
    // public IEnumerable<LoansHistories> loansHistories { get; set; }
   // public ICollection<WorkForLiving> workForLivings { get; set; }
   // public ICollection<CustomersCharacterBehavior> customersCharacterBehaviors { get; set; }
}

public class Loan
{
    [Key]
    public int LoanID { get; set; }
    [DataType(DataType.Currency)]
    [Column(TypeName = "money")]
    public decimal LoanAmount { get; set; }
    [NotMapped]
    public decimal TotalRepaidIn { get; set; }
    [NotMapped]
    public decimal Balance { get; set; }
    [DataType(DataType.Currency)]
    [Column(TypeName = "money")]
    [Display(Name = "Loan Balance")]
    private decimal _LoanBalance;

    public decimal LoanBalance
    {
        get { return LoanAmount * interestRate; }
        set { _LoanBalance = value; }
    }
    
    [Display(Name = "Interest Rate")]
    public decimal interestRate { get; set; }
    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
    [Display(Name = "Application Date")]
    public DateTime ApplicationDate { get; set; }
    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
    [Display(Name = "Disbursement Date")]
    public DateTime DisbursmentDate { get; set; }

    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
    [Display(Name = "Due Date")]
    public DateTime DueDate { get; set; }
    [Display(Name = "Defaulted")]
    public bool Defaulted { get; set; }
    [Display(Name = "Approved")]
    public bool Approved { get; set; }

    //Navigation property
    public int CustomerID { get; set; }
    public Customer customer { get; set; }

    //public ICollection<LoanComments> loancomments { get; set; }
    public ICollection<LoansHistories> loansHistories { get; set; }
}

public class LoansHistories
{
    [Key]
    public int HistID { get; set; }
    [DataType(DataType.Currency)]
    [Column(TypeName = "money")]
    [Display(Name = "Repaid Amount")]
    public decimal RePaidIn { get; set; }
   
    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
    [Display(Name = "Repayement Date")]
    public DateTime RepayementDateDate { get; set; }
    [Display(Name = "No of paying interest only")]
    public int NoOfPayinyingIntrestOnly { get; set; }

    // Navigation properties
    public int LoanID { get; set; }
    public Loan loan { get; set; }

    // Navigation property
    // public int CustomerID { get; set; }
    // public Customer customer { get; set; }
}

这是从 Loans 和 LoansHistories 加载数据的 LoansController tables:

[HttpGet]
public async Task<ActionResult<IEnumerable<Loan>>> Getloans()
{
    var data = await _context.loans
                             .Include(lh => lh.loansHistories)
                             .Select(l => new Loan()
        {
            TotalRepaidIn = l.loansHistories.Select(lh => lh.RePaidIn).Sum(),
            Balance = l.loansHistories.Select(lh => lh.RePaidIn).Sum()-l.LoanAmount,
            loansHistories = l.loansHistories,
            ApplicationDate = l.ApplicationDate,
            Defaulted = l.Defaulted,
            DisbursmentDate = l.DisbursmentDate,
            DueDate = l.DueDate,
            LoanID = l.LoanID,
            Approved = l.Approved,
            interestRate = l.interestRate,
            LoanAmount = l.LoanAmount
        }).ToListAsync();

    return data;
}

这是JSON格式的数据：

[
   {
      "loanID":1,
      "loanAmount":1000.0000,
      "totalRepaidIn":202700.0000,
      "balance":201700.0000,
      "loanBalance":15000.000000,
      "interestRate":15.00,
      "applicationDate":"2022-03-28T00:00:00",
      "disbursmentDate":"2022-03-28T00:00:00",
      "dueDate":"2022-04-28T00:00:00",
      "defaulted":false,
      "approved":true,
      "customerID":0,
      "customer":null,
      "loansHistories":[
         {
            "histID":1,
            "rePaidIn":500.0000,
            "repayementDateDate":"2022-03-28T00:00:00",
            "noOfPayinyingIntrestOnly":1,
            "loanID":1,
            "loan":null
         }
      ]
   }
]

我想从客户控制器加载数据，但我发现实体 TotalRepaidIn 为零，我怎样才能使它 return 一个值在贷款控制器中有其 returning？没有实体 totalRepaidIn":0.0

客户控制员：

  // GET: api/CustomersApi
    [HttpGet]
    public async Task<ActionResult<IEnumerable<Customer>>> Getcustomers()
    {
        return await _context.customers.Include(l=>l.loans).ThenInclude(h=>h.loansHistories).ToListAsync();
    }

return以下Json数据：

[
   {
      "customerID":30290122,
      "firstName":"Isaac",
      "lastName":"Kiplagat",
      "phoneNo":"0724797768",
      "nearestPrimarySchool":"Mokwo",
      "photo":"photo",
      "loans":[
         {
            "loanID":1,
            "loanAmount":1000.0000,
            "totalRepaidIn":0.0,
            "balance":0.0,
            "loanBalance":15000.000000,
            "interestRate":15.00,
            "applicationDate":"2022-03-28T00:00:00",
            "disbursmentDate":"2022-03-28T00:00:00",
            "dueDate":"2022-04-28T00:00:00",
            "defaulted":false,
            "approved":true,
            "customerID":30290122,
            "loansHistories":[
               {
                  "histID":1,
                  "rePaidIn":500.0000,
                  "repayementDateDate":"2022-03-28T00:00:00",
                  "noOfPayinyingIntrestOnly":1,
                  "loanID":1
               }
            ]
         }
      ]
   }
]

Answer 1

一种方法与之前一样，您可以 select 新的 Customer 实例并为它一个一个地设置值。

另一种更简单的方法，您可以将属性更改为以下以计算 RePaidIn:

using System.Linq;  //import this namespace...
public class Loan
{
    [Key]
    public int LoanID { get; set; }
    [DataType(DataType.Currency)]
    [Column(TypeName = "money")]

    public decimal LoanAmount { get; set; }

    private decimal _TotalRepaidIn;
    [NotMapped]
    public decimal TotalRepaidIn
    {
        get { return loansHistories.Sum(sum => sum.RePaidIn); }
        set { _TotalRepaidIn = value; }
    }
    //other properties
    public ICollection<LoansHistories> loansHistories { get; set; } = new List<LoansHistories>();  
}

并且在你的 LoansController 中，你可以将操作改进为以下：

var data = await _context.loans.Include(lh => lh.loansHistories).ToListAsync();

Customer Controller 也可以获得 TotalRepaidIn 的正确值。

在一对多关系中使用 Entity Framework Core 从 ASP.NET Core 中的三个相关表加载数据导致某些数据不显示

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