流畅的休眠映射问题：多对一...无法插入：[实体]

Question

我在 Foo 和 Bar 之间有一对多的关系，我无法执行插入（到目前为止我只尝试过 select 和 insert...select 似乎工作得很好，每次插入都失败）。

表定义：

CREATE TABLE [Bar](
[Id] [int] IDENTITY(1,1) NOT NULL,
[DateField] [datetime] NULL,
[StringField] [varchar](8000) NULL
CONSTRAINT [PK_Bar] PRIMARY KEY CLUSTERED([Id] ASC)) ON PRIMARY

CREATE TABLE [Foo](
[Id] [int] IDENTITY(1,1) NOT NULL,
[BarId] [int] NOT NULL,
[DateField] [date] NOT NULL,
[StringField] [varchar](100) NOT NULL,
[GorpId] [int] NOT NULL,
[BoolField] [bit] NOT NULL
CONSTRAINT [PK_Foo] PRIMARY KEY CLUSTERED([Id] ASC))

ALTER TABLE [dbo].[Foo]  WITH CHECK ADD  CONSTRAINT [FK_Foo_Bar] FOREIGN KEY([BarId])
REFERENCES [dbo].[Bar] ([Id])
GO

类定义：

public class Foo
{
    public virtual int Id { get; set; }
    public virtual Bar Bar{ get; set; }
    public virtual DateTime DateField{ get; set; }
    public virtual string StringField{ get; set; }
    public virtual Gorp Gorp{ get; set; }
    public virtual bool BoolField{ get; set; }
}

public class Bar
{
    public virtual int Id { get; set; }
    public virtual DateTime DateField{ get; set; }
    public virtual string StringField{ get; set; }

    public virtual ICollection<Foo> Foos{ get; set; }

    public Bar()
    {
        Foos= new List<Foo>();
    }

    public virtual void AddFoo(Foo foo)
    {
        foo.Bar = this;
        Foos.Add(foo);
    }
}

映射：

public class FooMap : ClassMap<Foo>
{
    public FooMap()
    {
        Id(x => x.Id).UnsavedValue(0).GeneratedBy.Identity();
        Map(x => x.DateField);
        Map(x => x.BoolField);
        Map(x => x.StringField);
        References(x => x.Gorp)
          .Column("GorpId")
          .Class<Gorp>();
        References(x => x.Bar)
          .Column("BarId")
          .Not.Nullable();
    }
}

public class BarMap : ClassMap<Bar>
{
    Id(x => x.Id).UnsavedValue(0).GeneratedBy.Identity();
    Map(x => x.DateField);
    Map(x => x.StringField);

    HasMany<Foo>(x => x.Foos)
      .AsBag()
      .Cascade.SaveUpdate()
      .ForeignKeyConstraintName("FK_Foo_Bar")
      .Inverse()
      .KeyColumn("BarId")
      .Not.KeyNullable();
}

生成的 XML：

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-access="property" auto-import="true" default-cascade="none" default-lazy="true">
    <class xmlns="urn:nhibernate-mapping-2.2" mutable="true" name="MyApp.Domain.Model.Bar, MyApp.Domain, Version=3.5.0.0, Culture=neutral, PublicKeyToken=null" table="`Bar`">
        <id name="Id" type="System.Int32, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" unsaved-value="0">
            <column name="Id" />
            <generator class="identity" />
        </id>
        <property name="DateField" type="System.DateTime, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
            <column name="DateField" />
        </property>
        <property name="StringField" type="System.String, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
            <column name="StringField" />
        </property>
        <bag cascade="save-update" inverse="true" name="Foos" mutable="true">
            <key foreign-key="FK_Foo_Bar" not-null="true">
                <column name="BarId" />
            </key>
            <one-to-many class="MyApp.Domain.Model.Foo, MyApp.Domain, Version=3.5.0.0, Culture=neutral, PublicKeyToken=null" />
        </bag>
    </class>
</hibernate-mapping>

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-access="property" auto-import="true" default-cascade="none" default-lazy="true">
    <class xmlns="urn:nhibernate-mapping-2.2" mutable="true" name="MyApp.Domain.Model.Foo, MyApp.Domain, Version=3.5.0.0, Culture=neutral, PublicKeyToken=null" table="`Foo`">
        <id name="Id" type="System.Int32, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" unsaved-value="0">
            <column name="Id" />
            <generator class="identity" />
        </id>
        <property name="DateField" type="System.DateTime, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
            <column name="DateField" />
        </property>
        <property name="BoolField" type="System.Boolean, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
            <column name="BoolField" />
        </property>
        <property name="StringField" type="System.String, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
             <column name="StringField" />
        </property>
        <many-to-one class="MyApp.Domain.Model.Gorp, MyApp.Domain, Version=3.5.0.0, Culture=neutral, PublicKeyToken=null" name="Gorp">
            <column name="GorpId" />
        </many-to-one>
        <many-to-one class="MyApp.Domain.Model.Bar, MyApp.Domain, Version=3.5.0.0, Culture=neutral, PublicKeyToken=null" insert="false" name="Bar" update="false">
            <column name="BarId" not-null="true" />
        </many-to-one>
    </class>
</hibernate-mapping>

例外：

无法插入：[MyApp.Domain.Model.Foo][SQL: INSERT INTO [Foo] (DateField, BoolField, StringField, GorpId, BarId) VALUES (?, ?, ?, ?, ?);选择 SCOPE_IDENTITY()]

我错过了什么/误解了什么？

Answer 1

谢谢你，戴夫，为我指明了正确的方向。数据库中的一个日期字段可以为空，而另一个则不是。我改变了我的班级和我的地图以反映这一点。瞧！成功了！

太糟糕了，原来的错误消息没有告诉我日期时间字段有问题，这会让我有些头疼。

我做了以下更改：

public class Foo
{
    public virtual int Id { get; set; }
    public virtual Bar Bar{ get; set; }
    public virtual DateTime DateField{ get; set; }
    public virtual string StringField{ get; set; }
    public virtual Gorp Gorp{ get; set; }
    public virtual bool BoolField{ get; set; }

    public Foo()
    {
        DateField = new DateTime(1753, 1, 1);
    }
}

public class Bar
{
    public virtual int Id { get; set; }
    public virtual DateTime? DateField{ get; set; }
    public virtual string StringField{ get; set; }

    public virtual ICollection<Foo> Foos{ get; set; }

    public Bar()
    {
        DateField = new DateTime(1753, 1, 1);
        Foos= new List<Foo>();
    }

    public virtual void AddFoo(Foo foo)
    {
        foo.Bar = this;
        Foos.Add(foo);
    }
}


public class FooMap : ClassMap<Foo>
{
    public FooMap()
    {
        Id(x => x.Id).UnsavedValue(0).GeneratedBy.Identity();
        Map(x => x.DateField);
        Map(x => x.BoolField);
        Map(x => x.StringField);
        References(x => x.Gorp)
          .Column("GorpId")
          .Class<Gorp>();
        References(x => x.Bar)
          .Column("BarId")
          .Not.Nullable();
    }
}

public class BarMap : ClassMap<Bar>
{
    Id(x => x.Id).UnsavedValue(0).GeneratedBy.Identity();
    Map(x => x.DateField)
          .Nullable();
    Map(x => x.StringField);

    HasMany<Foo>(x => x.Foos)
      .AsBag()
      .Cascade.SaveUpdate()
      .Fetch.Join()
      .ForeignKeyConstraintName("FK_Foo_Bar")
      .Inverse()
      .KeyColumn("BarId")
      .Not.KeyNullable()
      .Table("Foo");
}

Answer 2

如果在创建新对象时没有显式初始化属性，它将接收默认值。对于日期时间，默认值为 datetime.minvalue。

datetime.minvalue 是比 sql server 允许的更早的日期。 .net 和 sql server 不支持相同的日期时间范围，这是令人厌恶的，但事实就是如此。当您尝试将 datetime.minvalue 插入 sql server 时，您会看到您看到的异常。

解决方法是始终为该属性赋予新对象一个值，在数据库中为该列创建一个默认值，或者使 datatime 属性可以为空（DateTime？）。

这实际上与您的类的关系没有任何关系，只是与使用默认值的非初始化不可空日期时间属性有关。