Question

大家好，我试图编写可以使用（string）tableName获取选择表信息的代码，但是当我尝试将值放到Dictionary时，我收到错误。 P.S：我已经生成了EF DB模型。

public Dictionary<string, List<object>> GetTableInformation(string tableName, FinkonaDatabaseType type)
    {
        Dictionary<string, List<object>> _returnableDictionary = new Dictionary<string, List<object>>();
        PropertyInfo prop = optimumEntities.GetType().GetProperty(tableName);
        Type tableType = prop.PropertyType.GenericTypeArguments[0];
        var items = optimumEntities.Database.SqlQuery(tableType, "SELECT * FROM " + tableName);

        foreach (var item in items)
        {
            foreach (PropertyInfo info in item.GetType().GetProperties())
            {
                if (!_returnableDictionary.ContainsKey(info.Name))
                {
                    _returnableDictionary.Add(info.Name, new List<object>());
                }
                _returnableDictionary[info.Name].Add(info.GetValue(info, null)); 
                // System.Reflection.TargetException, Object does not match target type.
            }
        }
        return _returnableDictionary;
    }

Answer 1

使用ADO.NET DataTables在这里会更容易，因为EF用于强类型数据。由于您不太担心返回的数据类型，因此DataTable将更易于导航。

以下是此示例：

public Dictionary<string, List<object>> GetTableInformation(string tableName, FinkonaDatabaseType type)
{
   var sqlText = "SELECT * from " + tableName;
   DataTable dt = new DataTable();

   // Use DataTables to extract the whole table in one hit
   using(SqlDataAdapter da = new SqlDataAdapter(sqlText, optimumEntities.Database.ConnectionString)
   {
      da.Fill(dt);   
   }

   var tableData = new Dictionary<string, List<object>>();

   // Go through all columns, retrieving their names and populating the rows
   foreach(DataColumn dc in dt.Columns)
   {
      string columnName = dc.Name;
      rowData = new List<object>();
      tableData.Add(columnName, rowData);

      foreach(DataRow dr in dt.Rows)
      {
         rowData.Add(dr[columnName]);   
      }
   }

   return tableData;
}

将原始sql作为字典返回

1 个答案: