Question

我在使用asp.net核心项目中的Package Manager Console进行迁移时遇到了EntityFramework核心模型关系问题。

添加迁移时出现以下错误＆＃34;添加迁移＆＃34;。

无法确定导航属性＆＃39; College.Users＆＃39;所代表的关系。类型＆＃39; ICollection＆＃39;。手动配置关系，或从模型中忽略此属性。

完全错误

System.InvalidOperationException：无法确定导航属性＆＃39; College.Users＆＃39;所代表的关系。类型＆＃39; ICollection＆＃39;。手动配置关系，或从模型中忽略此属性。在Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.PropertyMappingValidationConvention.Apply（InternalModelBuilder modelBuilder）在Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.OnModelBuilt（InternalModelBuilder modelBuilder）在Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.CreateModel（DbContext上下文，IConventionSetBuilder conventionSetBuilder，IModelValidator验证器）在System.Collections.Concurrent.ConcurrentDictionary 2.GetOrAdd(TKey key, Func 2 valueFactory）在Microsoft.EntityFrameworkCore.Internal.DbContextServices.CreateModel（）在Microsoft.EntityFrameworkCore.Internal.LazyRef 1.get_Value() at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ServiceProvider.<>c__DisplayClass16_0.<RealizeService>b__0(ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService[T](IServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitTransient(TransientCallSite transientCallSite, ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitTransient(TransientCallSite transientCallSite, ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ServiceProvider.<>c__DisplayClass16_0.<RealizeService>b__0(ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType) at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider) at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType) at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType) at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0 1.b__0（）在Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute（Action action）无法确定导航属性所代表的关系。大学。用户＆＃39;类型＆＃39; ICollection＆＃39;。手动配置关系，或从模型中忽略此属性。

我有以下模特

public class College
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [JsonProperty("id")]
    public int Id { get; set; }

    [JsonProperty("name")]
    public string CollegeName { get; set; }

    [ForeignKey("Users")]
    [JsonProperty("users")]
    public ICollection<User> Users { get; set; }
}

public class User
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [JsonProperty("id")]
    public int Id { get; set; }

    [JsonProperty("name")]
    public string UserName { get; set; }

    [JsonProperty("email")]
    public string UserEmail { get; set; }

    [JsonProperty("phone")]
    public string UserPhone { get; set; }

    [ForeignKey("CollegeId")]
    [JsonProperty("college")]
    public College College{ get; set; }
}

请任何人对这个问题有所了解。

感谢

Answer 1

简答： 您使用的ForeignKey属性错误。删除它，您的迁移应该开始工作：

public class College
{
    public int Id { get; set; }
    public string CollegeName { get; set; }
    public ICollection<User> Users { get; set; }
}

public class User
{
    public int Id { get; set; }
    public string UserName { get; set; }
    public string UserEmail { get; set; }
    public string UserPhone { get; set; }
    public College College{ get; set; }
}

答案很长： 在您的示例中，您将遗漏模型上的外键ID属性。相反，您只包含导航属性。按照惯例，您可以通过将外键属性命名为与您引用的类相同并在末尾添加ID来包含该外键属性。在您的示例中：

public int CollegeId {get;set;}

如果您不想遵循此约定，可以使用ForeignKeyAttribute。让我们说，例如，您想要命名属性PrimaryCollegeId。您可以使用ForeignKeyAttribute这样做：

public int PrimaryCollegeId {get;set;}
[ForeignKey("PrimaryCollegeId")]
public College College {get;set;}

如果在同一个表之间存在多个关系，通常会使用ForeignKeyAttribute。例如，如果学生的小学和中学都是外键。

执行添加迁移时实体框架核心模型关系问题

1 个答案: