EF Core - 无法确定导航所代表的关系（一对多）

Question

我正在尝试创建一个简单的一对多关系，但 Ef Core 无法识别它。我仍然是这方面的初学者，但我认为我是按照书本（完全定义关系）做到的，所以我不明白为什么 EF Core 会抛出此错误：

Unable to determine the relationship represented by navigation 'Asset.Insurance' of type 'Insurance'. Either manually configure the relationship, or ignore this property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.

这是我的两个模型： Asset.cs

public class Asset
{
    public int AssetId { get; set; }
    public string AssetName { get; set; }

    [ForeignKey("AssetTypeId")]
    public int AssetTypeId { get; set; }
    public AssetType AssetType { get; set; }
    
    public ICollection<AssetValue> AssetTypeValues { get; set; }
    
    public string Brand { get; set; }
    public string Model { get; set; }
    public string SerialNumber { get; set; }
    public string ProductNumber { get; set; }
    public DateTime PurchaseDate { get; set; }
    public decimal PurchasePrice { get; set; }
    
    [ForeignKey("LocationId")]
    public int? LocationId { get; set; }
    public Location Location { get; set; }

    [ForeignKey("InsuranceId")]
    public int InsuranceId { get; set; }
    public Insurance Insurance { get; set; }

    [ForeignKey("OwnerId")]
    public string? OwnerId { get; set; }
    public AppUser Owner { get; set; }

    [ForeignKey("InvoiceId")]
    public int? InvoiceId { get; set; }
    public Insurance Invoice { get; set; }

    public string? ImagePath { get; set; }
    public string? Description { get; set; }
    public string CreatedBy { get; set; }
    public string ModifiedBy { get; set; }
    public DateTime DateCreated { get; set; }
    public DateTime DateModified { get; set; }
}

Insurance.cs

public class Insurance
{
    public int InsuranceId { get; set; }

    [ForeignKey("InsuranceTypeId")]
    public int InsuranceTypeId { get; set; }
    public InsuranceType InsuranceType { get; set; }

    public string Insurer { get; set; }
    public DateTime StartDate { get; set; }
    public DateTime EndDate { get; set; }
    public string? FilePath { get; set; }
    public string? Description { get; set; }
    public string CreatedBy { get; set; }
    public string ModifiedBy { get; set; }
    public DateTime DateCreated { get; set; }
    public DateTime DateModified { get; set; }

    public ICollection<Asset> Assets { get; set; }
}

此外，如果我删除这种关系，只是为了测试，迁移仍然不起作用，并且会抛出关于资产模型中其他外键的错误。是不是因为我的外键太多，所以我必须在OnModelCreating中定义它们？

编辑：ApplicationDbContext

public class ApplicationDbContext : IdentityDbContext<AppUser>
{
    public DbSet<Asset> Assets { get; set; }
    public DbSet<AssetType> AssetTypes { get; set; }
    public DbSet<AssetProp> AssetProps { get; set; }
    public DbSet<AssetValue> AssetValues { get; set; }
    public DbSet<Location> Locations { get; set; }
    public DbSet<Company> Companies { get; set; }
    public DbSet<CompanyContact> CompanyContacts { get; set; }
    public DbSet<Invoice> Invoices { get; set; }
    public DbSet<InsuranceType> InsuranceTypes { get; set; }
    public DbSet<Insurance> Insurances { get; set; }

    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
        : base(options)
    {
    }
}

Answer 1

如果指定 [ForeignKey] 属性，则需要执行以下两项操作之一：

将属性添加到标量属性，并使用导航名称属性；或
将属性添加到导航属性，并使用标量的名称属性。

所以要么：

[ForeignKey("Insurance")]
public int InsuranceId { get; set; }
public Insurance Insurance { get; set; }

或：

public int InsuranceId { get; set; }
[ForeignKey("InsuranceId")]
public Insurance Insurance { get; set; }

通过将属性放在标量属性上并指定标量的名称属性，EF 无法理解您要执行的操作。

这适用于您在代码中的所有 [ForeignKey("...")] 属性。

注意： 因为每个给定的实体类型只有一个导航属性，并且标量属性名称与导航属性添加了 Id 后缀的名称，实际上不需要 [ForeignKey] 属性。

编辑：

Insurance 实体有两个导航属性：

public Insurance Insurance { get; set; }
...
public Insurance Invoice { get; set; }

我怀疑第二个应该是：

public Invoice Invoice { get; set; }

EF Core - 无法确定导航所代表的关系（一对多）

EF Core - Unable to determine the relationship represented by navigation (One-to-Many)

c#

entity-framework

entity-framework-core

asp.net-core

编辑：