将 Nhibernate 查询转换为通用列表时出错 [英] Error while conversion of Nhibernate query to generic list

问题描述

我有一个名为 EmployeeEntity 的简单实体，其属性为 ID、Name、Age、Organisation 和 指定.我只是使用查询

I have a simple entity called EmployeeEntity with properties ID, Name, Age, Organisation, and Designation. I am just querying the database using the query

IQuery query = session.CreateQuery(
    "select Name, Designation, Age, Organisation FROM EmployeeEntity " +
    "group by Name, Designation, Age, Organisation");

IList<EmployeeEntity> employee = query.List<EmployeeEntity>(); // Throws error

但是在转换为我的类型时，它会引发异常:

but on conversion to my type, it's throwing an exception:

无法执行查询[SQL: SQL not available]

Could not execute query[SQL: SQL not available]

带有 InnerException:

值System.Object[]"不是NHibernateTest.EmployeeEntity"类型，不能在这个泛型集合中使用.
参数名称:值

The value "System.Object[]" is not of type "NHibernateTest.EmployeeEntity" and cannot be used in this generic collection.
Parameter name: value

虽然使用此查询可以正常工作:

though it works fine using this query:

IQuery query = session.CreateQuery("select e FROM EmployeeEntity e group by e");

IList<EmployeeEntity> employee = query.List<EmployeeEntity>();

但我不想选择所有列，因为我不需要它们.

but I don't want to select all the columns because I don't need them.

推荐答案

如果您只需要一组特定的列，请创建一个与您的列一对一映射的类.像这样:

If you only want a certain set of columns, create a class that maps one to one with your columns. Like so:

public class EmployeeView
{
    public string Name { get; set; }
    public string Designation { get; set; }
    public int Age { get; set; }
    public string Organization { get; set; }
}

然后你只需要在你的查询中添加一个结果转换器

You then just need to add a result transformer to your query

IQuery query = session
    .CreateQuery("select Name ,Designation ,Age ,Organisation  FROM EmployeeEntity   group by  Name ,Designation ,Age ,Organisation")
    .SetResultTransformer(Transformers.AliasToBean<EmployeeView>());

Ilist<EmployeeEntity> employee= query.List<EmployeeView>();

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