为什么这样的LINQ code总是抛出System.StackOverflowException？ [英] Why this Linq code always throws System.StackOverflowException?

问题描述

  //查询到本地的对象
 VAR deletionCommands =命令
     。凡（一个=＆GT;！a.Operation = Operation.Addition）
     。选择（A =＆gt;新建{。一个prestador.cod_ prestador，一个prestador.cod_desdobramento}）
     ;
 //一个LINQ到SQL查询
 VAR toDelete = DB。prestadors
     。凡（A =＆GT; deletionCommands.Contains（新{a.cod_ prestador，a.cod_desdobramento}））
     ;
 DB prestadors.DeleteAllOnSubmit（toDelete）。
 db.SubmitChanges（）;
 

这是解决问题的唯一事情是明确的循环：

 的foreach（在命令VAR命令）
 {
    如果（command.Operation！= Operation.Addition）
    {
        VAR toDelete = DB。prestadors
            。凡（一个=＆GT;
                a.cod_ prestador ==命令prestador.cod_ prestador和放大器;＆安培;
                a.cod_desdobramento ==命令。prestador.cod_desdobramento
            ）;
        DB prestadors.DeleteAllOnSubmit（toDelete）。
    }
 }
 db.SubmitChanges（）;
 

解决方案

这是一个真正的错误，并在LINQ 4.0已得到纠正

的http：// damieng。 COM /博客/ 2009/06/01 / LINQ到SQL的变化，在净40

  

查询稳定   包含现在检测自引用的IQueryable和不会导致堆栈溢出

修改在.NET 3.5中解决这个问题：当使用自动生成的值'= TRUE，则必须将延迟加载'为False - 否则，你得到的递归错误。

EDIT2 上述方案没有奏效。

 //A query to a local object
 var deletionCommands = commands
     .Where(a => a.Operation != Operation.Addition)
     .Select(a => new { a.Prestador.cod_prestador, a.Prestador.cod_desdobramento })
     ;
 //A Linq-To-SQL query
 var toDelete = db.Prestadors
     .Where(a => deletionCommands.Contains(new { a.cod_prestador, a.cod_desdobramento }))
     ;
 db.Prestadors.DeleteAllOnSubmit(toDelete);
 db.SubmitChanges();

The only thing that solved the problem was an explicit loop:

 foreach (var command in commands)
 {
    if(command.Operation != Operation.Addition)
    {
        var toDelete = db.Prestadors
            .Where(a =>
                a.cod_prestador == command.Prestador.cod_prestador &&
                a.cod_desdobramento == command.Prestador.cod_desdobramento
            );
        db.Prestadors.DeleteAllOnSubmit(toDelete);
    }
 }
 db.SubmitChanges();

解决方案

That was really a bug, and was corrected in LINQ 4.0

http://damieng.com/blog/2009/06/01/linq-to-sql-changes-in-net-40

Query stability Contains now detects self-referencing IQueryable and doesn't cause a stack overflow

EDIT In .NET 3.5 to resolve the problem: When using 'Auto Generated Value' = True, then you must set 'Delay Loaded' to False - otherwise you get the recursion error.

EDIT2 The solution above didn't work.

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