EF核心:无导航属性的映射多对多关系

Question

我正在尝试使用Fluent API在实体框架核心中创建多对多关系这是我的第一个型号：

MyCalculationSelector.cs

public int SortOrder { get; set; }
public string UserString { get { return Name; } }
private IList<CalculationType> _calculationTypes;
public virtual IList<CalculationType> CalculationTypes
{
get { return _calculationTypes; }
set { _calculationTypes = value; }
}

这是我的第二个型号：

MyCalculationType.cs

public int SortOrder { get; set; }
public string UserString
{
get { return Name; }
}
public int CalculationMethod { get; set; }

我记得EF 6可以很容易地建立Fluent API的多对多关系：

modelBuilder.Entity<MyCalculationSelector>().HasMany(x => x.MyCalculationTypes).WithMany();

我们能在ef核心中实现这样的目标吗？到目前为止，Hasmany-Withmany实现是不可能的

Answer 1

您可以用私有字段或属性表示：

modelBuilder.Entity<MyCalculationSelector>()
.HasMany(x => x.MyCalculationTypes)
.WithMany("NameOfThePrivateFieldOnMyCalculationType");

这样，导航属性就不会公开，但您仍然可以在MyCalculationSelector上使用导航属性，而无需遍历中间联接表。

Answer 2

我遵循了文档并给出了这个答案，请比我了解更多的人，如果我错了，他会纠正我。

我首先创建了我的联接表：

CalculationSelectorCalculationType.cs

public class CalculationSelectorCalculationType
{
public int CalculationSelector_Id { get; set; }
public CalculationSelector CalculationSelector { get; set; }
public int CalculationType_Id { get; set; }
public CalculationType CalculationType { get; set; }
}

CalculationSelector.cs

public CalculationSelector()
{
_calculationTypes = new List<CalculationSelectorCalculationType>();
FontSize = 30;
}
public int SortOrder { get; set; }
public string UserString { get { return Name; } }
private IList<CalculationSelectorCalculationType> _calculationTypes;
public virtual IList<CalculationSelectorCalculationType> CalculationTypes
{
get { return _calculationTypes; }
set { _calculationTypes = value; }
}

CalculationType.cs

public int SortOrder { get; set; }
public string UserString
{
get { return Name; }
}
public int CalculationMethod { get; set; }

最后是我的DbContext:

modelBuilder.Entity<CalculationSelectorCalculationType>().HasKey(p => new { p.CalculationSelector_Id, p.CalculationType_Id });
modelBuilder.Entity<CalculationSelectorCalculationType>().HasOne(p => p.CalculationSelector).WithMany(x => x.CalculationTypes).HasForeignKey(p => p.CalculationSelector_Id);
modelBuilder.Entity<CalculationSelectorCalculationType>().HasOne(p => p.CalculationType).WithMany().HasForeignKey(p => p.CalculationType_Id);