我有几个方法返回不同的泛型列表。
在。net中存在任何类静态方法或将任何列表转换为数据表?我唯一能想到的是使用反射来做到这一点。
如果我有这个:
List<Whatever> whatever = new List<Whatever>();
(这下代码当然不工作,但我想有这样的可能性:
DataTable dt = (DataTable) whatever;
我有几个方法返回不同的泛型列表。
在。net中存在任何类静态方法或将任何列表转换为数据表?我唯一能想到的是使用反射来做到这一点。
如果我有这个:
List<Whatever> whatever = new List<Whatever>();
(这下代码当然不工作,但我想有这样的可能性:
DataTable dt = (DataTable) whatever;
当前回答
如果你的类中有属性,这行代码是OK的!!
PropertyDescriptorCollection props =
TypeDescriptor.GetProperties(typeof(T));
但如果你有所有的公共字段,那么使用这个:
public static DataTable ToDataTable<T>( IList<T> data)
{
FieldInfo[] myFieldInfo;
Type myType = typeof(T);
// Get the type and fields of FieldInfoClass.
myFieldInfo = myType.GetFields(BindingFlags.NonPublic | BindingFlags.Instance
| BindingFlags.Public);
DataTable dt = new DataTable();
for (int i = 0; i < myFieldInfo.Length; i++)
{
FieldInfo property = myFieldInfo[i];
dt.Columns.Add(property.Name, property.FieldType);
}
object[] values = new object[myFieldInfo.Length];
foreach (T item in data)
{
for (int i = 0; i < values.Length; i++)
{
values[i] = myFieldInfo[i].GetValue(item);
}
dt.Rows.Add(values);
}
return dt;
}
原来的答案是从上面,我只是编辑使用字段而不是属性
然后这样使用它
DataTable dt = new DataTable();
dt = ToDataTable(myBriefs);
gridData.DataSource = dt;
gridData.DataBind();
其他回答
Marc Gravell的回答,但是用VB。网
Public Shared Function ToDataTable(Of T)(data As IList(Of T)) As DataTable
Dim props As PropertyDescriptorCollection = TypeDescriptor.GetProperties(GetType(T))
Dim table As New DataTable()
For i As Integer = 0 To props.Count - 1
Dim prop As PropertyDescriptor = props(i)
table.Columns.Add(prop.Name, prop.PropertyType)
Next
Dim values As Object() = New Object(props.Count - 1) {}
For Each item As T In data
For i As Integer = 0 To values.Length - 1
values(i) = props(i).GetValue(item)
Next
table.Rows.Add(values)
Next
Return table
End Function
public DataTable ConvertToDataTable<T>(IList<T> data)
{
PropertyDescriptorCollection properties =
TypeDescriptor.GetProperties(typeof(T));
DataTable table = new DataTable();
foreach (PropertyDescriptor prop in properties)
table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
foreach (T item in data)
{
DataRow row = table.NewRow();
foreach (PropertyDescriptor prop in properties)
{
row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
}
table.Rows.Add(row);
}
return table;
}
另一种方法是:
List<WhateEver> lst = getdata();
string json = Newtonsoft.Json.JsonConvert.SerializeObject(lst);
DataTable pDt = JsonConvert.DeserializeObject<DataTable>(json);
您可以尝试以下内容
public static DataTable GetDataTableFromObjects(object[] objects)
{
if (objects != null && objects.Length > 0)
{
Type t = objects[0].GetType();
DataTable dt = new DataTable(t.Name);
foreach (PropertyInfo pi in t.GetProperties())
{
dt.Columns.Add(new DataColumn(pi.Name));
}
foreach (var o in objects)
{
DataRow dr = dt.NewRow();
foreach (DataColumn dc in dt.Columns)
{
dr[dc.ColumnName] = o.GetType().GetProperty(dc.ColumnName).GetValue(o, null);
}
dt.Rows.Add(dr);
}
return dt;
}
return null;
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.ComponentModel;
public partial class Default3 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
DataTable dt = new DataTable();
dt = lstEmployee.ConvertToDataTable();
}
public static DataTable ConvertToDataTable<T>(IList<T> list) where T : class
{
try
{
DataTable table = CreateDataTable<T>();
Type objType = typeof(T);
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(objType);
foreach (T item in list)
{
DataRow row = table.NewRow();
foreach (PropertyDescriptor property in properties)
{
if (!CanUseType(property.PropertyType)) continue;
row[property.Name] = property.GetValue(item) ?? DBNull.Value;
}
table.Rows.Add(row);
}
return table;
}
catch (DataException ex)
{
return null;
}
catch (Exception ex)
{
return null;
}
}
private static DataTable CreateDataTable<T>() where T : class
{
Type objType = typeof(T);
DataTable table = new DataTable(objType.Name);
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(objType);
foreach (PropertyDescriptor property in properties)
{
Type propertyType = property.PropertyType;
if (!CanUseType(propertyType)) continue;
//nullables must use underlying types
if (propertyType.IsGenericType && propertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
propertyType = Nullable.GetUnderlyingType(propertyType);
//enums also need special treatment
if (propertyType.IsEnum)
propertyType = Enum.GetUnderlyingType(propertyType);
table.Columns.Add(property.Name, propertyType);
}
return table;
}
private static bool CanUseType(Type propertyType)
{
//only strings and value types
if (propertyType.IsArray) return false;
if (!propertyType.IsValueType && propertyType != typeof(string)) return false;
return true;
}
}