转换IEnumerable< T>到EntitySet< T> [英] Convert IEnumerable<T> to EntitySet<T>

问题描述

如何转换IEnumerable< T>到EntitySet< T>？

var questions =来自e.Element中的q（"问题"）。元素（"问题"）

选择新问题
{
Text = q.Attribute （" title"）。Value，
Point = Convert.ToDecimal（q.Attribute（" point"。）。），
Choices = from c在q.Elements（"Choices"）中。元素（"Choice"）
选择新的选择
{
Text = c.Attribute（" title"）。Value，
Correct = Convert.ToBoolean（c.Attribute（" isCorrect"）。Value）
}

;

以粗体显示的行抛出错误：

错误1无法隐式将类型'System.Collections.Generic.IEnumerable< DomainObjects.Choice>'转换为'System.Data.Linq.EntityS等人LT; DomainObjects.Choice>"。存在显式转换（您是否缺少演员表？）C：\Projects \ExamDLINQ \ExamDLINQSolution\ExamDLINQConsole\Program.cs 29 43 ExamDLINQConsole


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解决方案

我认为没有任何内置方法可以实现这一目标。推测问题是一个LINQ to SQL实体，你想在之后插入到表中？

一种解决方案是编写自己的ToEntitySet扩展方法：

public static EntitySet< T> ToEntitySet< T> （此IEnumerable< T>源）其中T：class
{
var es = new EntitySet< T> （）;
es.AddRange（source）;
return es;
}

然后你可以编写你的查询如下：

var questions = from e inElement（" Questions" ;）元素（"问题"） 结果

Hi,

How can I convert IEnumerable<T> to EntitySet<T>?

 var questions = from q in e.Element("Questions").Elements("Question")

                            select new Question
                            {
                                Text = q.Attribute("title").Value,
                                Point = Convert.ToDecimal(q.Attribute("point").Value),
                                Choices = from c in q.Elements("Choices").Elements("Choice")
                                          select new Choice
                                          {                                         
                                              Text = c.Attribute("title").Value,
                                              Correct = Convert.ToBoolean(c.Attribute("isCorrect").Value)
                                          }                                          
                            };

The lines in bold throw the error:

Error    1    Cannot implicitly convert type 'System.Collections.Generic.IEnumerable<DomainObjects.Choice>' to 'System.Data.Linq.EntitySet<DomainObjects.Choice>'. An explicit conversion exists (are you missing a cast?)    C:\Projects\ExamDLINQ\ExamDLINQSolution\ExamDLINQConsole\Program.cs    29    43    ExamDLINQConsole



                           

解决方案

I don't think there's any built-in way to achieve this. Presumably Question is a LINQ to SQL entity which you want to insert into the table afterward?

One solution would be to write your own ToEntitySet extension method:

    public static EntitySet<T> ToEntitySet<T> (this IEnumerable<T> source) where T : class
    {
        var es = new EntitySet<T> ();
        es.AddRange (source);
        return es;
    }

Then you could write your query as follows:

var questions = from q in e.Element("Questions").Elements("Question")

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