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[英]Entity Framework 4.1: Unable to cast from DbQuery to ObjectQuery
[英]Entity Framework 6 and DBContext or DBQuery or DBSet or ObjectQuery with scalar variable
我正在嘗試將變量傳遞給我的 DBContext 擴展。 它適用於固定字符串但當我嘗試使用變量時出現錯誤“必須聲明標量變量@p_linq_0”
var pn = "6-10064-01";
// put query results into datatable
var query = db.SWD_0004.Where(p => p.Part_Number == pn) as DbQuery<SWD_0004>;
var numResults = query.Count();
DataTable dt = db.DataTable(query.ToString());
// gets column names and put into array
List<DataRow> list = dt.AsEnumerable().ToList();
string[] columnList = dt.Columns.Cast<DataColumn>()
.Select(x => x.ColumnName)
.ToArray();
var rowCount = dt.Rows.Count;
var columnCount = dt.Columns.Count;
for (var j = 0; j < rowCount; j++)
{
for (var i = 1; i < columnCount; i++) // skip ID column
{
var columnName = columnList[i];
var data = list[j][i].ToString();
lstName.Items.Add(columnName);
lstData.Items.Add(data);
}
}
public static class DbContextExtensions
{
public static DataTable DataTable(this DbContext context, string query)
{
DbProviderFactory dbFactory = DbProviderFactories.GetFactory(context.Database.Connection);
using (var cmd = dbFactory.CreateCommand())
{
cmd.Connection = context.Database.Connection;
cmd.CommandType = CommandType.Text;
cmd.CommandText = query;
using (DbDataAdapter adapter = dbFactory.CreateDataAdapter())
{
adapter.SelectCommand = cmd;
DataTable dt = new DataTable();
adapter.Fill(dt);
return dt;
}
}
}
}
我嘗試了一些轉換為 ObjectQuery、DBQuery 等的方法,但沒有結果。 我很困惑,需要一些方向。
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