我正在使用EF核心,并在每个级别结构(TPH)方法中实现继承。我发现,一旦我将层次结构对象添加到数据模型中,迁移将为基础表添加外键,并且似乎是后裔类正在使用的重复。
关系是从 Transaction
(parent)到 TransactionItem
(child)。
对象层次结构:
- TransActionItem(基类)
- 附件
- 检查
- 信封
- 存根
使用fluent API使用TransactionItem.TransactionId
字段作为外键来定义Transaction
和TransactionItem
之间的关系:
modelBuilder.Entity<TransactionItem>(t =>
{
t.ToTable("TransactionItem");
t.HasKey(a => a.Id);
t.Property(a => a.ConcurrencyStamp)
.IsRequired()
.IsConcurrencyToken();
t.Property(a => a.Created)
.IsRequired();
t.HasOne(a => a.Transaction)
.WithMany(a => a.TransactionItems)
.HasForeignKey(a => a.TransactionId)
.OnDelete(DeleteBehavior.Restrict);
t.HasDiscriminator<string>("ItemType")
.HasValue<Check>("Check")
.HasValue<Stub>("Stub")
.HasValue<Envelope>("Envelope")
.HasValue<Attachment>("Attachment");
});
使用TransactionId
和TransactionId2
列创建基类表(TPH)的迁移方法,每列与同一父表有关:
migrationBuilder.CreateTable(
name: "TransactionItem",
columns: table => new
{
Id = table.Column<int>(nullable: false)
.Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
ConcurrencyStamp = table.Column<string>(nullable: false),
Created = table.Column<DateTimeOffset>(nullable: false),
ItemType = table.Column<string>(nullable: false),
PageName = table.Column<string>(nullable: true),
Sequence = table.Column<int>(nullable: false),
TransactionId = table.Column<int>(nullable: false),
TransactionId2 = table.Column<int>(nullable: true),
CheckType = table.Column<string>(nullable: true),
Micr = table.Column<string>(nullable: true),
MicrValid = table.Column<bool>(nullable: true),
OcrId = table.Column<string>(nullable: true)
},
constraints: table =>
{
table.PrimaryKey("PK_TransactionItem", x => x.Id);
table.ForeignKey(
name: "FK_TransactionItem_Transaction_TransactionId",
column: x => x.TransactionId,
principalTable: "Transaction",
principalColumn: "Id",
onDelete: ReferentialAction.Restrict);
table.ForeignKey(
name: "FK_TransactionItem_Transaction_TransactionId2",
column: x => x.TransactionId2,
principalTable: "Transaction",
principalColumn: "Id",
onDelete: ReferentialAction.Restrict);
});
当我查看ModelsNapShot.cs代码时,我会看到以下针对继承模型中对象特定的关系,该关系使用TransactionId2
列为派生类实体建立外键。
modelBuilder.Entity("SampleProject.Data.DataModels.TransactionItem", b =>
{
b.HasOne("SampleProject.Data.DataModels.Transaction", "Transaction")
.WithMany("TransactionItems")
.HasForeignKey("TransactionId");
});
modelBuilder.Entity("SampleProject.Data.DataModels.Attachment", b =>
{
b.HasOne("SampleProject.Data.DataModels.Transaction")
.WithMany("Attachments")
.HasForeignKey("TransactionId2");
});
modelBuilder.Entity("SampleProject.Data.DataModels.Check", b =>
{
b.HasOne("SampleProject.Data.DataModels.Transaction")
.WithMany("Checks")
.HasForeignKey("TransactionId2");
});
modelBuilder.Entity("SampleProject.Data.DataModels.Envelope", b =>
{
b.HasOne("SampleProject.Data.DataModels.Transaction")
.WithMany("Envelopes")
.HasForeignKey("TransactionId2");
});
modelBuilder.Entity("SampleProject.Data.DataModels.Stub", b =>
{
b.HasOne("SampleProject.Data.DataModels.Transaction")
.WithMany("Stubs")
.HasForeignKey("TransactionId2");
});
我显然缺少一些东西,但无法弄清楚它是什么。我希望能够使用TPH方法使用继承层次结构,从基类表(TransactionItem
)到父(Transaction
)。感谢您可以提供的任何帮助。
谢谢!
正如Ivan Stoev所指出的那样,我通过让父对象(在这种情况下为Transaction
)实现我的列表列表属性来创建此问题派生类型。
因为Transaction
声明了以下类似的属性,因此EF迁移正在为其创建新的关系/外键。
public List<Check> Checks
{
get
{
return this.TransactionItems?.OfType<Check>().ToList();
}
}
此后,我已经实施了这些方法,以免与EF的惯例冲突。
非常感谢Ivan Stoev提示此发现!