Linq To EF：如何使用非原始类型进行过滤

发布于 2024-11-02 14:36:24 字数 736 浏览 0 评论 0原文

public class Person
{
   public int ID { get; set; }
   public int Job { get; set; }
   public string Name { get; set; }
}

List<Person> personsOfInterest = GetPersonsOfInterest();

PersonEntities personEntities = new PersonEntities();

var filteredPersons = personEntities.Where(p => personsOfInterest.Any(poi => poi.Job == p.Job && poi.Name == p.Name));

上面的代码生成 NotSupportedException，因为 Linq to Entities 不支持引用非标量变量 (Person)。

我该如何解决这个问题？谢谢！

//编辑：我试图从 personEntities 中查找人员，他们与 personOfInterest 列表中的任何人具有相同的姓名和相同的工作。例如，我试图在我的实体中找到一个名为 Bob 的警察或名为 John 的程序员。
我收到的错误在此处中进行了描述。(22.2)

原文

public class Person
{
   public int ID { get; set; }
   public int Job { get; set; }
   public string Name { get; set; }
}

List<Person> personsOfInterest = GetPersonsOfInterest();

PersonEntities personEntities = new PersonEntities();

var filteredPersons = personEntities.Where(p => personsOfInterest.Any(poi => poi.Job == p.Job && poi.Name == p.Name));

The above code generates a NotSupportedException, because Linq to Entities does not support referencing non-scalar variables(Person).

how can I resolve this? thanks!

//edit: I am trying to find persons from personEntities, who has same name and same job with anyone in the personOfInterest list. for example, I am trying to find anyone in my personEntities who is a Policeman named Bob or Programmer named John.
the error I'm getting is described in here.(22.2)

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流殇 2024-11-09 14:36:24

首先，两个集合应该包含相同类型的对象。

然后你可以执行以下操作：

    var filteredPerosns = personEntities
          .Where(p => personsOfInterest.Contains(p, new MyPersonComparer()));

创建类：

    class MyPersonComparer : IEqualityComparer<Person>
    {
        public bool Equals(Person x, Person y)
        {
            return x.Job == y.Job && x.Name == y.Name; 
        }

        public int GetHashCode(Person obj)
        {
            return obj.PersonID; //Just for example...
        }
    }

OR如果第一个不是一个选项，你可以按照以下方式进行连接（概念上）：

    List<int?> listA = new List<int?>() {1, 2, 3, 4, 5, 6, 7};
    List<int?> listB = new List<int?>() {5};

    bool result = (from a in listA
                   join b in listB on a equals b 
                   select a).Any();

我不知道内部情况您的类，因此您必须调整示例以适应您的对象结构。

编辑：
我修改了上面的示例以反映您编辑的描述：

    List<Person> personsOfInterest = GetPersonsOfInterest();

    var filteredPersons = (from a in personEntities
           join b in personsOfInterest on new{a.Name, a.Job} equals new {b.Name, b.Job} 
           select a).ToList();

代码中的 PersonEntities，是自定义集合类型还是 EF 模型中的表/复杂类型？

First of all both collections should contain objects of the same type.

Then you could do the following:

    var filteredPerosns = personEntities
          .Where(p => personsOfInterest.Contains(p, new MyPersonComparer()));

create the class:

    class MyPersonComparer : IEqualityComparer<Person>
    {
        public bool Equals(Person x, Person y)
        {
            return x.Job == y.Job && x.Name == y.Name; 
        }

        public int GetHashCode(Person obj)
        {
            return obj.PersonID; //Just for example...
        }
    }

OR if the first is not an option, you could do a join something along the lines(in concept):

    List<int?> listA = new List<int?>() {1, 2, 3, 4, 5, 6, 7};
    List<int?> listB = new List<int?>() {5};

    bool result = (from a in listA
                   join b in listB on a equals b 
                   select a).Any();

I do not know the insides of your classes, so you will have to adjust the examples to fit your object structure.

EDITED:
I have modified the above example to reflect your edited description:

    List<Person> personsOfInterest = GetPersonsOfInterest();

    var filteredPersons = (from a in personEntities
           join b in personsOfInterest on new{a.Name, a.Job} equals new {b.Name, b.Job} 
           select a).ToList();

PersonEntities in your code, is that a custom collection type or is this a table/complex type in your EF model?

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