将select new转换为DataTable
本文关键字:DataTable 转换 new select | 更新日期: 2023-09-27 18:29:24
我使用的是.NET 3.5,需要将下面的select新结果转换为DataTable。有什么内置的东西吗?或者有人知道可以做到这一点的方法吗?
var contentList = (from item in this.GetData().Cast<IContent>()
select new
{
Title = item.GetMetaData("Title"),
Street = item.GetMetaData("Street"),
City = item.GetMetaData("City"),
Country = item.GetMetaData("Country")
});
简单而直接的方法是使用反射:
var records = (from item in this.GetData().Cast<IContent>()
select new
{
Title = "1",
Street = "2",
City = "3",
Country = "4"
});
var firstRecord = records.First();
if (firstRecord == null)
return;
var infos = firstRecord.GetType().GetProperties();
DataTable table = new DataTable();
foreach (var info in infos) {
DataColumn column = new DataColumn(info.Name, info.PropertyType);
table.Columns.Add(column);
}
foreach (var record in records) {
DataRow row = table.NewRow();
for (int i = 0; i < table.Columns.Count; i++)
row[i] = infos[i].GetValue(record);
table.Rows.Add(row);
}
代码可能不起作用,但应该给你一个大致的想法。首先,您从匿名类型获取propertyInfo,并使用此元数据创建数据表架构(填充列)。然后使用这些信息从每个对象中获取值。
这里有一个没有对属性进行反射的通用解决方案。具有如下的扩展方法
public static DataTable ConvertToDataTable<TSource>(this IEnumerable<TSource>
records, params Expression<Func<TSource, object>>[] columns)
{
var firstRecord = records.First();
if (firstRecord == null)
return null;
DataTable table = new DataTable();
List<Func<TSource, object>> functions = new List<Func<TSource, object>>();
foreach (var col in columns)
{
DataColumn column = new DataColumn();
column.Caption = (col.Body as MemberExpression).Member.Name;
var function = col.Compile();
column.DataType = function(firstRecord).GetType();
functions.Add(function);
table.Columns.Add(column);
}
foreach (var record in records)
{
DataRow row = table.NewRow();
int i = 0;
foreach (var function in functions)
{
row[i++] = function((record));
}
table.Rows.Add(row);
}
return table;
}
并使用相同的方法调用,其中参数将按所需顺序作为列名。
var table = records.ConvertToDataTable(
item => item.Title,
item => item.Street,
item => item.City
);
您可以通过以下函数将列表结果转换为数据表
public static DataTable ToDataTable<T>(IEnumerable<T> values)
{
DataTable table = new DataTable();
foreach (T value in values)
{
if (table.Columns.Count == 0)
{
foreach (var p in value.GetType().GetProperties())
{
table.Columns.Add(p.Name);
}
}
DataRow dr = table.NewRow();
foreach (var p in value.GetType().GetProperties())
{
dr[p.Name] = p.GetValue(value, null) + "";
}
table.Rows.Add(dr);
}
return table;
}
有一个CopyToDataTable
扩展方法可以为您做到这一点。它位于System.Data.DataSetExtensions.dll 中
// Create your datatable.
DataTable dt = new DataTable();
dt.Columns.Add("Title", typeof(string));
dt.Columns.Add("Street", typeof(double));
// get a list of object arrays corresponding
// to the objects listed in the columns
// in the datatable above.
var result = from item in in this.GetData().Cast<IContent>()
select dt.LoadDataRow(
new object[] { Title = item.GetMetaData("Title"),
Street = item.GetMetaData("Street"),
},
false);
// the end result will be a set of DataRow objects that have been
// loaded into the DataTable.
代码示例的原始文章:将LINQ生成的匿名类型转换为DataTable类型
编辑:通用伪码:
void LinqToDatatable(string[] columns, Type[] datatypes, linqSource)
{
for loop
{
dt.columns.add(columns[i], datatypes[i]);
}
//Still thinking how to make this generic..
var result = from item in in this.GetData().Cast<IContent>()
select dt.LoadDataRow(
new object[] { string[0] = item.GetMetaData[string[0]],
string[1] = item.GetMetaData[srring[1]
},
false);
}
public static DataTable ListToDataTable<T>(this IList<T> data)
{
DataTable dt = new DataTable();
PropertyDescriptorCollection props = TypeDescriptor.GetProperties(typeof(T));
for (int i = 0; i < props.Count; i++)
{
PropertyDescriptor prop = props[i];
dt.Columns.Add(prop.Name, prop.PropertyType);
}
object[] values = new object[props.Count];
foreach (T t in data)
{
for (int i = 0; i < values.Length; i++)
{
values[i] = props[i].GetValue(t);
}
dt.Rows.Add(values);
}
return dt;
}
完成新的选择后,您可以进入.ToList().ListToDataTable()
。这使用ComponentModel反射,并且(理论上)比System.reflection快。