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EF Core 2.0迁移-多对多以及其他字段

ef-core-2.0 many-to-many entity-framework

okieh · 技术社区 · 8 年前

我正在使用EF Core 2.0,并与join实体建立了多对多关系。当我添加新的迁移时,EF总是创建一个额外的索引/Id字段,这完全是愚蠢的。这是我的加入实体:

public class Team_Member
{
    public int TeamId { get; set; }
    public Team Team { get; set; }

    public int MemberId { get; set; }
    public Member Member { get; set; }

    public MemberTypeEnum MemberType { get; set; }
}

这是联接表的配置(以下是internet上的几个示例):

public class Team_MemberConfig : IEntityTypeConfiguration<Team_Member>
{
    public void Configure(EntityTypeBuilder<Team_Member> builder)
    {
        builder.ToTable("Team_Member");
        builder.HasKey(tm => new { tm.TeamId, tm.MemberId });
        builder.HasOne<Team>()
            .WithMany(t => t.Team_Member)
            .HasForeignKey(tm => tm.TeamId)
            .OnDelete(DeleteBehavior.Restrict);
        builder.HasOne<Member>()
            .WithMany(m => m.Team_Member)
            .HasForeignKey(tm => tm.MemberId)
            .OnDelete(DeleteBehavior.Restrict);
    }
}

对于每个外键列,迁移都会添加第二个外键列:

columns: table => new
            {
                TeamId = table.Column<int>(nullable: false),
                MemberId = table.Column<int>(nullable: false),
                **MemberId1** = table.Column<int>(nullable: true),
                MemberType = table.Column<int>(nullable: false),
                **TeamId1** = table.Column<int>(nullable: true)
            },

以及两个完全相同的约束:

table.ForeignKey(
                    name: "FK_Team_Member_Member_MemberId",
                    column: x => x.MemberId,
                    principalTable: "Member",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Restrict);
                table.ForeignKey(
                    name: "FK_Team_Member_Member_MemberId1",
                    column: x => x.MemberId1,
                    principalTable: "Member",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Restrict);
                table.ForeignKey(
                    name: "FK_Team_Member_Team_TeamId",
                    column: x => x.TeamId,
                    principalTable: "Team",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Restrict);
                table.ForeignKey(
                    name: "FK_Team_Member_Team_TeamId1",
                    column: x => x.TeamId1,
                    principalTable: "Team",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Restrict);

我做错了什么?

1 回复 | 直到 8 年前

Ivan Stoev 8 年前

无论何时,只要看到EF(Core)生成额外的FK列,就可以清楚地看到由于使用错误的fluent API重载而导致的未映射引用或集合导航属性。所有相关fluent API( HasOne , HasMany , WithOne , WithMany )具有带导航属性且不带导航属性的重载。当对应实体没有导航时,必须使用第一个,并且应该使用 准确的 一个表示相应实体中是否存在导航属性的属性。否则将留下未映射的导航属性,EF将创建其他关系。

在您的情况下,两个差异(标记为A、B)介于:

public class Team_Member
{
    public int TeamId { get; set; }
    public Team Team { get; set; } // <-- A

    public int MemberId { get; set; }
    public Member Member { get; set; } // <-- B

    public MemberTypeEnum MemberType { get; set; }
}

和

builder.HasOne<Team>() // <-- A
    .WithMany(t => t.Team_Member)
    .HasForeignKey(tm => tm.TeamId)
    .OnDelete(DeleteBehavior.Restrict);
builder.HasOne<Member>() // <-- B
    .WithMany(m => m.Team_Member)
    .HasForeignKey(tm => tm.MemberId)
    .OnDelete(DeleteBehavior.Restrict);

如前所述,只需让它们匹配即可:

builder.HasOne(tm => tm.Team) // <-- A
    .WithMany(t => t.Team_Member)
    .HasForeignKey(tm => tm.TeamId)
    .OnDelete(DeleteBehavior.Restrict);
builder.HasOne(tm => tm.Member) // <-- B
    .WithMany(m => m.Team_Member)
    .HasForeignKey(tm => tm.MemberId)
    .OnDelete(DeleteBehavior.Restrict);

问题已经解决了。