Csharp EF Core：如何对关系属性进行建模

您的两个关系图都显示了一对多关系，而在您的实体代码中您声明了unidirectional many-to-many个关系.如果您确实需要多对多(即系统可以有多个组件，并且组件可以属于多个系统)，则只需添加payload to the join table即可.最简单的 Select 是声明显式联接实体:

public class SystemComponentVersion
{
    public int Id { get; set; } 
    public System System{ get; set; }
    public Component Component { get; set; }
    public string Version { get; set; }
}

public class System
{
    public string SystemId { get; set; }
    public List<Component> Components { get; set; } = new List<Component>();
    public List<SystemComponentVersion> SystemComponents{ get; set; } = new List<SystemComponentVersion>();
}

public class Component
{
    public int ComponentId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }

    public List<System> Systems { get; set; } = new List<System>();
    public List<SystemComponentVersion> SystemComponents{ get; set; } = new List<SystemComponentVersion>();
}

通过流畅的API提供了以下内容:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<System>()
        .HasMany(e => e.Components)
        .WithMany(e => e.Systems)
        .UsingEntity<SystemComponentVersion>());
}