Question

This是我的数据库项目的片段，this是Fluent NHibernate自动生成的数据库的片段

这些是我在上面数据库项目的Fluent NHibernate中的实体和映射类。

实体：

public class BaseEntity<T> where T : BaseEntity<T> {
    public virtual int Id { get; set; }
...
}

public class Person<T> : BaseEntity<T> where T : BaseEntity<T> {
    public virtual string FirstName { get; set; }
    public virtual string SecondName { get; set; }
    public virtual string LastName { get; set; }
    public virtual string PESEL { get; set; }
    public virtual DateTime BirthDate { get; set; }
    public virtual string City { get; set; }
    public virtual string PostalCode { get; set; }
    public virtual string Street { get; set; }
    public virtual string HouseNr { get; set; }
    public virtual string ApartmentNr { get; set; }
    public virtual string PhoneNr { get; set; }
    public virtual string Email { get; set; }
}

public class DrivingLicense : BaseEntity<DrivingLicense> {
    #region Relations
    public virtual IList<DrivingLicensePermissions> DrivingLicensePermissions { get; set; }
    public virtual Student Student { get; set; }
    #endregion

    public virtual DateTime IssueDate { get; set; }
    public virtual string DrivingLicenseNr { get; set; }
}

public class DrivingLicensePermissions : BaseEntity<DrivingLicensePermissions> {
    #region Relations
    public virtual DrivingLicense DrivingLicense { get; set; }
    #endregion

    public virtual DrivingLicenseCategory Category { get; set; }
}

映射：

class StudentMap : ClassMap<Student> {
    public StudentMap() {
        Id(x => x.Id);
        Map(x => x.FirstName).Not.Nullable().Length(25);
        Map(x => x.SecondName).Nullable().Length(25);
        Map(x => x.LastName).Not.Nullable().Length(50);
        Map(x => x.PESEL).Nullable().Length(11);
        Map(x => x.BirthDate).Not.Nullable();
        Map(x => x.City).Not.Nullable().Length(50);
        Map(x => x.PostalCode).Nullable().Length(6);
        Map(x => x.Street).Not.Nullable().Length(50);
        Map(x => x.HouseNr).Not.Nullable().Length(10);
        Map(x => x.ApartmentNr).Nullable().Length(10);
        Map(x => x.PhoneNr).Nullable().Length(20);
        Map(x => x.Email).Nullable().Length(100);

        References(x => x.DrivingLicense).Nullable().Cascade.All();
        References(x => x.User).Nullable().Cascade.All();
        HasMany(x => x.Participants).Cascade.All();
    }
}

class DrivingLicenseMap : ClassMap<DrivingLicense> {
    public DrivingLicenseMap() {
        Id(x => x.Id);
        Map(x => x.IssueDate).Not.Nullable();
        Map(x => x.DrivingLicenseNr).Not.Nullable().Length(20);

        HasMany(x => x.DrivingLicensePermissions).Cascade.All();
        References(x => x.Student).Not.Nullable();
    }
}

class DrivingLicensePermissionsMap : ClassMap<DrivingLicensePermissions> {
    public DrivingLicensePermissionsMap() {
        Id(x => x.Id);
        Map(x => x.Category).Not.Nullable();

        References(x => x.DrivingLicense).Not.Nullable();
    }
}

我的问题是这个例外： not-null属性引用了null或瞬态值Model.Entities.DrivingLicense.Student ，而我正试图坚持学生object 就像这样

session.Save(student);

已将DrivingLicense对象分配给它的DrivingLicense属性。

我认为它是由于错误的映射造成的 - 错误的级联或缺少反向。我尝试了很多组合，但却无法正常工作。也是正确的，Student表有DrivingLicense_id，反之，DrivingLicense有Student_id列吗？！

Answer 1

此问题的关键是DrivingLicense通过Student映射引用Not.Nullable()。这意味着当NH尝试保留DrivingLicense时，其Student属性不得为null。

调试代码并暂停Save(student)调用。检查对象图，查看student的{{1}}属性及其DrivingLicense属性。我的猜测是Student。

您需要查看地图的null方面，或确保您的对象图表已正确连线。在坚持之前。

Answer 2

要解决我的问题，我必须将参考引用更改为HasOne-to-Reference。

现在看起来像这样。

实体尚未更改

<强>映射：

class StudentMap : ClassMap<Student> {
    public StudentMap() {
        Id(x => x.Id);
        Map(x => x.FirstName).Not.Nullable().Length(25);
        Map(x => x.SecondName).Nullable().Length(25);
        Map(x => x.LastName).Not.Nullable().Length(50);
        Map(x => x.PESEL).Nullable().Length(11);
        Map(x => x.BirthDate).Not.Nullable();
        Map(x => x.City).Not.Nullable().Length(50);
        Map(x => x.PostalCode).Nullable().Length(6);
        Map(x => x.Street).Not.Nullable().Length(50);
        Map(x => x.HouseNr).Not.Nullable().Length(10);
        Map(x => x.ApartmentNr).Nullable().Length(10);
        Map(x => x.PhoneNr).Nullable().Length(20);
        Map(x => x.Email).Nullable().Length(100);

        HasOne(x => x.DrivingLicense).PropertyRef(x => x.Student).Cascade.All();
        References(x => x.User).Unique().Not.Nullable();
        HasMany(x => x.Participants).Cascade.All();
    }
}

class DrivingLicenseMap : ClassMap<DrivingLicense> {
    public DrivingLicenseMap() {
        Id(x => x.Id);
        Map(x => x.IssueDate).Not.Nullable();
        Map(x => x.DrivingLicenseNr).Not.Nullable().Length(20);

        HasMany(x => x.DrivingLicensePermissions).Cascade.All();
        References(x => x.Student).Unique().Not.Nullable();
    }
}

class DrivingLicensePermissionsMap : ClassMap<DrivingLicensePermissions> {
    public DrivingLicensePermissionsMap() {
        Id(x => x.Id);
        Map(x => x.Category).Not.Nullable();

        References(x => x.DrivingLicense).Nullable();
    }
}

感谢这一变化，循环引用已经消失。 see it here

学生表中没有DrivingLicense_id，现在我可以将学生实体与DrivingLicense一起保留，并且只是通过保存学生的权限，就像我以前那样。

session.Save(student);

not-null属性引用null或transient值 - 理解Inverse和Cascade

2 个答案: