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如何在Fluent NHibernate中启用LazyLoad?

fluent-nhibernate nhibernate

David · 技术社区 · 14 年前

班雇员

public class Employee
{
    public virtual int EmployeeID { get; private set; }
    public virtual string LastName { get; set; }
    public virtual string FirstName { get; set; }
    public virtual string Title { get; set; }
    public virtual string TitleOfCourtesy { get; set; }
    public virtual DateTime? BirthDate { get; set; }
    public virtual DateTime? HireDate { get; set; }
    public virtual string Address { get; set; }
    public virtual string City { get; set; }
    public virtual string Region { get; set; }
    public virtual string PostalCode { get; set; }
    public virtual string Country { get; set; }
    public virtual string HomePhone { get; set; }
    public virtual string Extension { get; set; }
    public virtual string Notes { get; set; }
    public virtual Employee ReportsTo { get; set; }
    public virtual string PhotoPath { get; set; }

    public virtual IList<Territory> Territories{ get; set; }

    public Employee()
    {
        Territories = new List<Territory>();
    }

    public virtual void AddTerritory(Territory territory)
    {
        territory.Employees.Add(this);
        this.Territories.Add(territory);
    }
}

班员工地图

public class EmployeeMap : ClassMap<Employee>
{
    public EmployeeMap()
    {
        Table("Employees");

        Id(x => x.EmployeeID);
        Map(x => x.LastName);
        Map(x => x.FirstName);
        Map(x => x.Title);
        Map(x => x.TitleOfCourtesy);
        Map(x => x.BirthDate);
        Map(x => x.HireDate);
        Map(x => x.Address);
        Map(x => x.City);
        Map(x => x.Region);
        Map(x => x.PostalCode);
        Map(x => x.Country);
        Map(x => x.HomePhone);
        Map(x => x.Extension);
        Map(x => x.Notes);
        Map(x => x.PhotoPath);
        References(x => x.ReportsTo).Column("ReportsTo").LazyLoad();

        HasManyToMany(x => x.Territories)
        .Cascade.All()
        .Table("EmployeeTerritories")
        .ParentKeyColumn("EmployeeID")
        .ChildKeyColumn("TerritoryID");
    }
}

var sessionFactory = CreateSessionFactory();

using (var session = sessionFactory.OpenSession())
{
    using (session.BeginTransaction())
    {
        Console.WriteLine("All employees");

        var emp_ = session.CreateCriteria(typeof(Employee));
        var employees = emp_.List<Employee>();

        foreach (var employee in employees)
        {
            Console.WriteLine(employee.FirstName); // every employee has reference object on ReportsTo property here.
        }

        Console.Write("--------");
    }
}

2 回复 | 直到 14 年前

Diego Mijelshon 14 年前

-2

rebelliard 14 年前

默认情况下不启用延迟加载。

public EmployeeMap()
{
    Table("Employees");
    LazyLoad();

    // etc.
}

也就是说,使用foreach语句进行测试可能是有害的,因为即使启用了延迟加载,在查询“employee.FirstName”时,NHibernate也会命中数据库并返回结果。最好是使用NHibernate生成的SQL,或者只使用 NHibernate Profiler .