C# 用C中的LINQ填充数据表
我的应用程序中有一个方法,使用以下代码用数据填充DataTable:C# 用C中的LINQ填充数据表,c#,linq,datatable,C#,Linq,Datatable,我的应用程序中有一个方法,使用以下代码用数据填充DataTable: DataTable dt = this.attachmentsDataSet.Tables["Attachments"]; foreach (Outlook.Attachment attachment in this.mailItem.Attachments) { DataRow dr = dt.NewRow(); dr["Index"] = attachment.Index; dr["Display
DataTable dt = this.attachmentsDataSet.Tables["Attachments"];
foreach (Outlook.Attachment attachment in this.mailItem.Attachments)
{
DataRow dr = dt.NewRow();
dr["Index"] = attachment.Index;
dr["DisplayName"] = String.Format(
CultureInfo.InvariantCulture,
"{0} ({1})",
attachment.FileName,
FormatSize(attachment.Size));
dr["Name"] = attachment.FileName;
dr["Size"] = attachment.Size;
dt.Rows.Add(dr);
}
我想知道是否可以使用LINQ实现相同的功能,以便将代码缩短一点。有什么想法吗?首先确定是否可以查询this.mailItem.Attachments和
如果可能的话,您可以将查询结果从扩展方法createby…转换为datatable。这段代码并不短,也不是Linq,但我做了一个扩展方法,它接受IList并将其转换为datatable
public static DataTable ToDataTable<T>(this IList<T> theList)
{
DataTable theTable = CreateTable<T>();
Type theEntityType = typeof(T);
// Use reflection to get the properties of the generic type (T)
PropertyDescriptorCollection theProperties = TypeDescriptor.GetProperties(theEntityType);
// Loop through each generic item in the list
foreach (T theItem in theList)
{
DataRow theRow = theTable.NewRow();
// Loop through all the properties
foreach (PropertyDescriptor theProperty in theProperties)
{
// Retrieve the value and check to see if it is null
object thePropertyValue = theProperty.GetValue(theItem);
if (null == thePropertyValue)
{
// The value is null, so we need special treatment, because a DataTable does not like null, but is okay with DBNull.Value
theRow[theProperty.Name] = DBNull.Value;
}
else
{
// No problem, just slap the value in
theRow[theProperty.Name] = theProperty.GetValue(theItem);
}
}
theTable.Rows.Add(theRow);
}
return theTable;
}
是的,很简单
public void FillFromList(List<T> col)
{
Type elementType = typeof(T);
// Nested query of generic element list of property
// values (using a join to the DataTable columns)
var rows = from row in col
select new
{
Fields = from column in m_dataTable.Columns.Cast<DataColumn>()
join prop in elementType.GetProperties()
on column.Caption equals prop.Name
select prop.GetValue(row, null)
};
// Add each row to the DataTable
int recordCount = 0;
foreach ( var entry in rows )
{
m_dataTable.Rows.Add(entry.Fields.ToArray());
}
这假设T上的属性与DataTable列相同。您使用DataTable的目的是什么?是数据库插入吗?我没有使用数据库。它是用来填充listbox数据源的。