C# 在这种情况下，如何对实体执行级联删除？

如何让entity framework从EsignatureDocument中删除字段和事件（定义如下），而不会导致错误？我怀疑我可以编写一些模型构建代码，使用EntityTypeConfiguration在DbContext中的应用程序启动时执行这些代码。。。以下示例的生成器代码是什么

我有一块很短的C#能用。这是：

    var document = _repo.Load<EsignatureDocument>(input.EsignatureDocumentId);

document.Events.Clear();

                document.Fields.Clear();

            _repo.SaveChanges();

Clear（）删除对父实体的引用，而不是子实体本身

问题是，当调用document.Fields.Clear（）时，它将使字段实体上的EsignatureDocumentId列为空。这是不允许的，因为EsignatureDocumentId不可为空，因此您不能拥有没有父文档的字段。 您应该将该列标记为可空，或者应该使用：

foreach(var f in document.Field) 
{
    Context.DeleteObject(f); //or fieldRepo.Delete(f) or something that fits for 
}

---

如果调用

RemoveAll（t=>true）

而不是

Clear（）

在HashSet上没有RemoveAll，但是当我执行document.Fields.RemoveWhere（x=>x.esignateDocumentId==input.esignateDocumentId）时会发生什么；当我从HashSet更改为List并执行RemoveAll时，仍然会出现相同的错误

CREATE TABLE [dbo].[EsignatureDocumentEvent](
    [Id] [uniqueidentifier] NOT NULL,
    [EsignatureDocumentId] [uniqueidentifier] NOT NULL,
    [Action] [int] NOT NULL,
    [ActionName] [varchar](50) NOT NULL,
    [FieldsJson] [varchar](max) NULL,
    [DocumentPdf] [varchar](1000) NULL,
    [CreatedDate] [datetime] NOT NULL,
 CONSTRAINT [PK_EsignatureDocumentEvent] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO



  ALTER TABLE [dbo].[EsignatureDocumentEvent]  WITH CHECK ADD  CONSTRAINT [FK_EsignatureDocumentEvent_EsignatureDocument] FOREIGN KEY([EsignatureDocumentId])
    REFERENCES [dbo].[EsignatureDocument] ([Id])
    GO

    ALTER TABLE [dbo].[EsignatureDocumentEvent] CHECK CONSTRAINT [FK_EsignatureDocumentEvent_EsignatureDocument]
    GO

CREATE TABLE [dbo].[EsignatureDocumentField](
    [Field_Id] [int] NOT NULL,
    [Field_Name] [varchar](100) NOT NULL,
    [Field_Value] [varchar](1000) NOT NULL,
    [Field_Type] [varchar](100) NOT NULL,
    [EsignatureDocumentId] [uniqueidentifier] NOT NULL,
PRIMARY KEY CLUSTERED 
(
    [Field_Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

ALTER TABLE [dbo].[EsignatureDocumentField]  WITH CHECK ADD  CONSTRAINT [FK_EsignatureDocumentField_EsignatureDocument] FOREIGN KEY([EsignatureDocumentId])
REFERENCES [dbo].[EsignatureDocument] ([Id])
GO

ALTER TABLE [dbo].[EsignatureDocumentField] CHECK CONSTRAINT [FK_EsignatureDocumentField_EsignatureDocument]
GO

foreach(var f in document.Field) 
{
    Context.DeleteObject(f); //or fieldRepo.Delete(f) or something that fits for 
}