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
private DataTable CreateDataTable(IList<T> item)
{
Type type = typeof(T);
var properties = type.GetProperties();
DataTable dataTable = new DataTable();
foreach (PropertyInfo info in properties)
{
dataTable.Columns.Add(new DataColumn(info.Name, Nullable.GetUnderlyingType(info.PropertyType) ?? info.PropertyType));
}
foreach (T entity in item)
{
object[] values = new object[properties.Length];
for (int i = 0; i < properties.Length; i++)
{
values[i] = properties[i].GetValue(entity);
}
dataTable.Rows.Add(values);
}
return dataTable;
}
其他回答
private DataTable CreateDataTable(IList<T> item)
{
Type type = typeof(T);
var properties = type.GetProperties();
DataTable dataTable = new DataTable();
foreach (PropertyInfo info in properties)
{
dataTable.Columns.Add(new DataColumn(info.Name, Nullable.GetUnderlyingType(info.PropertyType) ?? info.PropertyType));
}
foreach (T entity in item)
{
object[] values = new object[properties.Length];
for (int i = 0; i < properties.Length; i++)
{
values[i] = properties[i].GetValue(entity);
}
dataTable.Rows.Add(values);
}
return dataTable;
}
It's also possible through XmlSerialization.
The idea is - serialize to `XML` and then `readXml` method of `DataSet`.
I use this code (from an answer in SO, forgot where)
public static string SerializeXml<T>(T value) where T : class
{
if (value == null)
{
return null;
}
XmlSerializer serializer = new XmlSerializer(typeof(T));
XmlWriterSettings settings = new XmlWriterSettings();
settings.Encoding = new UnicodeEncoding(false, false);
settings.Indent = false;
settings.OmitXmlDeclaration = false;
// no BOM in a .NET string
using (StringWriter textWriter = new StringWriter())
{
using (XmlWriter xmlWriter = XmlWriter.Create(textWriter, settings))
{
serializer.Serialize(xmlWriter, value);
}
return textWriter.ToString();
}
}
so then it's as simple as:
string xmlString = Utility.SerializeXml(trans.InnerList);
DataSet ds = new DataSet("New_DataSet");
using (XmlReader reader = XmlReader.Create(new StringReader(xmlString)))
{
ds.Locale = System.Threading.Thread.CurrentThread.CurrentCulture;
ds.ReadXml(reader);
}
Not sure how it stands against all the other answers to this post, but it's also a possibility.
如果你想使用反射并设置列的顺序/只包括一些列/排除一些列,试试这个:
private static DataTable ConvertToDataTable<T>(IList<T> data, string[] fieldsToInclude = null,
string[] fieldsToExclude = null)
{
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(typeof(T));
DataTable table = new DataTable();
foreach (PropertyDescriptor prop in properties)
{
if ((fieldsToInclude != null && !fieldsToInclude.Contains(prop.Name)) ||
(fieldsToExclude != null && fieldsToExclude.Contains(prop.Name)))
continue;
table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
}
foreach (T item in data)
{
var atLeastOnePropertyExists = false;
DataRow row = table.NewRow();
foreach (PropertyDescriptor prop in properties)
{
if ((fieldsToInclude != null && !fieldsToInclude.Contains(prop.Name)) ||
(fieldsToExclude != null && fieldsToExclude.Contains(prop.Name)))
continue;
row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
atLeastOnePropertyExists = true;
}
if(atLeastOnePropertyExists) table.Rows.Add(row);
}
if (fieldsToInclude != null)
SetColumnsOrder(table, fieldsToInclude);
return table;
}
private static void SetColumnsOrder(DataTable table, params String[] columnNames)
{
int columnIndex = 0;
foreach (var columnName in columnNames)
{
table.Columns[columnName].SetOrdinal(columnIndex);
columnIndex++;
}
}
这是一个简单的混合溶液。 它适用于Nullable类型。
public static DataTable ToDataTable<T>(this IList<T> list)
{
PropertyDescriptorCollection props = TypeDescriptor.GetProperties(typeof(T));
DataTable table = new DataTable();
for (int i = 0; i < props.Count; i++)
{
PropertyDescriptor prop = props[i];
table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
}
object[] values = new object[props.Count];
foreach (T item in list)
{
for (int i = 0; i < values.Length; i++)
values[i] = props[i].GetValue(item) ?? DBNull.Value;
table.Rows.Add(values);
}
return table;
}
试试这个
public static DataTable ListToDataTable<T>(IList<T> lst)
{
currentDT = CreateTable<T>();
Type entType = typeof(T);
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(entType);
foreach (T item in lst)
{
DataRow row = currentDT.NewRow();
foreach (PropertyDescriptor prop in properties)
{
if (prop.PropertyType == typeof(Nullable<decimal>) || prop.PropertyType == typeof(Nullable<int>) || prop.PropertyType == typeof(Nullable<Int64>))
{
if (prop.GetValue(item) == null)
row[prop.Name] = 0;
else
row[prop.Name] = prop.GetValue(item);
}
else
row[prop.Name] = prop.GetValue(item);
}
currentDT.Rows.Add(row);
}
return currentDT;
}
public static DataTable CreateTable<T>()
{
Type entType = typeof(T);
DataTable tbl = new DataTable(DTName);
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(entType);
foreach (PropertyDescriptor prop in properties)
{
if (prop.PropertyType == typeof(Nullable<decimal>))
tbl.Columns.Add(prop.Name, typeof(decimal));
else if (prop.PropertyType == typeof(Nullable<int>))
tbl.Columns.Add(prop.Name, typeof(int));
else if (prop.PropertyType == typeof(Nullable<Int64>))
tbl.Columns.Add(prop.Name, typeof(Int64));
else
tbl.Columns.Add(prop.Name, prop.PropertyType);
}
return tbl;
}