将LINQ结果集转换为数据表时出现问题 [英] Problem in converting LINQ result set to datatable

问题描述

你好朋友
我必须将linq结果集转换为datatable
为此，我正在使用代码

Hello friends
i have to convert my linq result set to datatable
for this i am using the code

char HeadType = _session.HeadType;
     var res = db.DispHed(_session.CompId;
     DataView dv = _global.ToDataTable(db, res).DefaultView;

和类文件中的ToDataTable方法是

and ToDataTable methos in class file is

public DataTable ToDataTable(System.Data.Linq.DataContext ctx, object query) 
    {
        DataTable dt = new DataTable();
        if (query != null)
        {
            IDbCommand cmd = ctx.GetCommand(query as IQueryable);
            SqlDataAdapter adapter = new SqlDataAdapter();
            adapter.SelectCommand = (SqlCommand)cmd;
            try
            {
                cmd.Connection.Open();
                adapter.FillSchema(dt, SchemaType.Source);
                adapter.Fill(dt);
            }
            finally
            {
                cmd.Connection.Close();
            }
        }
        return dt; 
    } 

但在到达线
IDbCommand cmd = ctx.GetCommand(可查询为IQueryable);
它给出了错误

but on reaching line
IDbCommand cmd = ctx.GetCommand(query as IQueryable);
it is giving error

<pre lang="msil">Value cannot be null.<br />
Parameter name: query</pre>

在此先感谢

thanks in advance

推荐答案

问题与调用ToDataTable的方法有关:作为"query"传递的对象不为null，但未实现IQueryable接口.
结果，强制转换query as IQueryable返回null，并且ctx.GetCommand抱怨.

The problem is to do with whatever is calling ToDataTable: the object passed as "query" is not null, but it does not implement the IQueryable interface.
As a result, the cast query as IQueryable returns null, and ctx.GetCommand complains.

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