如何调用动态指定不同表名的 Linq-to-Entities (EF4) 查询？

发布于 2024-12-11 02:38:09 字数 851 浏览 0 评论 0原文

我有一堆表，它们都有一个名为 ResourceID 的字段，该字段是从外部进程填充的。我想遍历每个表并根据主列表验证该 ID。代码很简单，但很重复：

var resList = (from r in dc.ResourceMasterEntities select r.ResourceId).ToList();
var res = (from rs in resList select (int?)rs).ToList();

    var stage = (from s in dc.TableOne select s.ResourceId).ToList();
    foreach (var invalidResourceID in stage.Except(res).ToList())
    {
        errList.Add("Bad ID found:" + invalidResourceID );
    }

    stage = (from s in dc.TableTwo select s.ResourceId).ToList();
    foreach (var invalidResourceID in stage.Except(res).ToList())
    {
        errList.Add("Bad ID found:" + invalidResourceID );
    }

    // more of the same with different tables

我想创建一个函数，可以在其中传递表的名称（TableOne、TableTwo 等），而不必编写所有这些重复的代码。这可以用 Linq 来完成吗？（最好不要使用 ExecuteQuery :-)）

原文

I have a bunch of tables that all have a field called ResourceID that are populated from an outside process. I want to go through each table and validate that ID against a master list. The code is simple but gets repetitive:

var resList = (from r in dc.ResourceMasterEntities select r.ResourceId).ToList();
var res = (from rs in resList select (int?)rs).ToList();

    var stage = (from s in dc.TableOne select s.ResourceId).ToList();
    foreach (var invalidResourceID in stage.Except(res).ToList())
    {
        errList.Add("Bad ID found:" + invalidResourceID );
    }

    stage = (from s in dc.TableTwo select s.ResourceId).ToList();
    foreach (var invalidResourceID in stage.Except(res).ToList())
    {
        errList.Add("Bad ID found:" + invalidResourceID );
    }

    // more of the same with different tables

I would like to create a function where I can pass in the name of the table (TableOne, TableTwo, etc) and not have to write all of this repetitive code. Can this be done with Linq? (and preferably not using ExecuteQuery :-))

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季末如歌 2024-12-18 02:38:09

您可以创建一个采用 IQueryable 作为参数的函数。

该函数如下所示：

  private void CheckTable(IQueryable<EntityType> table)
  {
      var stage = (from s in table select s.ResourceId).ToList();
      foreach (var invalidResourceID in stage.Except(res).ToList())
      {
          errList.Add("Bad ID found:" + invalidResourceID);
      }
  }

  // Execute the function like:
  CheckTable(dc.TableOne);

您可以选择是否创建 errList 和 res 类级别属性，或者将它们作为参数传递给函数

You can create a function that takes an IQueryable as a parameter.

The function would look like:

  private void CheckTable(IQueryable<EntityType> table)
  {
      var stage = (from s in table select s.ResourceId).ToList();
      foreach (var invalidResourceID in stage.Except(res).ToList())
      {
          errList.Add("Bad ID found:" + invalidResourceID);
      }
  }

  // Execute the function like:
  CheckTable(dc.TableOne);

You can choose if you make errList and res class level properties or if you pas them as parameters to the function

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空气里的味道 2024-12-18 02:38:09

经过一些修改，我能够让它工作 - 我必须使用内置的动态 linq 来选择我想要的属性。

private void CheckTable(System.Data.Objects.ObjectSet<EntityType> table)   
{
        var records = table.Select("BusinessEntityNbr").ToList();
        var values = (from r in records select (int?)r[0]).ToList();

        foreach (var invalidResourceID in values.Except(res).ToList())       
        {
           errList.Add("Bad ID found:" + invalidResourceID);       
        }
}

With some modification I was able to get this to work - I had to use the built in dynamic linq to select the property that I wanted.

private void CheckTable(System.Data.Objects.ObjectSet<EntityType> table)   
{
        var records = table.Select("BusinessEntityNbr").ToList();
        var values = (from r in records select (int?)r[0]).ToList();

        foreach (var invalidResourceID in values.Except(res).ToList())       
        {
           errList.Add("Bad ID found:" + invalidResourceID);       
        }
}

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