Question

我正在努力掌握EF4 CTP5。我有两个类具有多对多关系：Member和MemberGroup。CTP5代码首先生成了两个表（Members和MemberGroups），还有第三个名为MemberGroupMembers的表，它有两列（MemberGroupId和MemberId）。到目前为止，一切都如我所期望的那样。我已经为数据库添加了一些Members和MemberGroups。问题是，我找不到如何将一个或多个MemberGroup分配给某个成员，这将导致在MemberGroupMembers表中为分配给该成员的每个MemberGroup插入一行。

    public class Member
{
    public int Id { get; set; }

    public Guid SecureId { get; set; }

    public DateTime JoinedOn { get; set; }

    public virtual ICollection<MemberGroup> MemberGroups { get; set; }
}

public class MemberGroup
{
    public int Id { get; set; }

    public string Name { get; set; }

    public DateTime CreatedOn { get; set; }

    public virtual ICollection<Member> Members { get; set; }
}

public class CTP5testContext : DbContext
{
    public CTP5testContext() : base("CTP5test") { }

    public DbSet<Member> Members { get; set; }

    public DbSet<MemberGroup> MemberGroups { get; set; }
}

public class CTP5testContextInitializer : DropCreateDatabaseIfModelChanges<CTP5testContext>
{
    protected override void Seed(CTP5testContext context)
    {
        new List<Member>
        {
            new Member
            {
                Id = 1,
                SecureId = Guid.NewGuid(),
                JoinedOn = DateTime.Now
            }
            ,
            new Member
            {
                Id = 2,
                SecureId = Guid.NewGuid(),
                JoinedOn = DateTime.Now
            }
        }.ForEach(m => context.Members.Add(m));

        var memberGroup = new MemberGroup()
        {
            Id = 1,
            Name = "MemberGroup 1",
            CreatedOn = DateTime.Now
        };

        context.MemberGroups.Add(memberGroup);

        // How can I assign Member 1 to MemberGroup 1 ?????

        context.SaveChanges();
    }
}

我希望我在这里要做的事情很清楚，有人能给我一个如何实现这一目标的例子。

Regards, Erwin

Answer 1

您必须使用在POCO类中定义的集合。因此，如果您想将member1分配给memberGroup，只需调用：

memberGroup.Members.Add(member1);

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