I need to create a DataTable from another DataTable that I have but with only some columns (exactly same rows).
Is there an easy way to do this using LINQ?
I tried:
DataTable dataCopy = dt.AsEnumerable()
.Select(r => new { A = r.Field<string>("Column A"),
B = r.Field<string>("Column B") });
But it doesn't have a "CopyToDataTable" method.
I'm looking for the best performance way to do this because my "source" DataTable is huge!
You can simply copy the dataTable using dataTable.Copy() and remove the unwanted columns from the copied object.
var dt1 = dt.Copy();
dt.Columns.Remove("<columnsToRemove>")
Stopwatch time = new Stopwatch();
time.Start();
//COMPARE YOUR CODE (.Copy, Clone or Develop yourself)
DataTable dtTarget = dtSource.CopyDataTable(new List<string>() { "A", "B" });
foreach (DataColumn column in dtTarget.Columns)
{
Console.WriteLine("ColumnName : {0}", column.ColumnName);
foreach (DataRow row in dtTarget.Rows)
{
Console.WriteLine("Rows : {0}", row[column.ColumnName]);
}
}
time.Stop();
Console.WriteLine("{0}", time.Elapsed);
public static class DataTableHelper
{
public static DataTable CopyDataTable(
this DataTable dtSource,
List<string> columnsName)
{
DataTable dtTarget = new DataTable();
if (dtSource.Columns.Count > 0)
{
foreach (DataColumn columnSource in dtSource.Columns)
{
var columnTargetMapped = columnsName.FirstOrDefault(c => c == columnSource.ColumnName);
if(columnTargetMapped == null)
{
continue;
}
dtTarget.Columns.Add(columnTargetMapped);
foreach (DataRow drSource in dtSource.Rows)
{
var valueColumn = drSource[columnSource];
DataRow drTarget = dtTarget.NewRow();
drTarget[columnTargetMapped] = valueColumn;
dtTarget.Rows.Add(drTarget);
}
}
}
return dtTarget;
}
public static DataTable GetDataTablePart(this DataTable dt, params string[] ColumnNames)
{
var dtPart = new DataTable("TablePart");
var Names = new List<DataColumn>();
foreach (DataColumn Column in dt.Columns)
{
if(ColumnNames.Contains(Column.ColumnName))
{
Names.Add(Column);
}
}
dtPart.Columns.AddRange(Names.ToArray());
foreach(DataRow row in dt.Rows)
{
var NewRow = new object[Names.Count()];
var i = 0;
foreach (var Name in Names)
{
NewRow[i] = row[Name];
i = i + 1;
}
dtPart.LoadDataRow(NewRow, false);
}
return dtPart;
}
linq version....
public static DataTable GetDataTablePart(this DataTable dt, params string[] ColumnNames)
{
var RowCount = 0;
var dtPart = new DataTable("TablePart");
dtPart.Columns.AddRange((from column in dt.Columns.Cast<DataColumn>()
where ColumnNames.Contains(column.ColumnName)
select column).ToArray());
return (from row in dt.AsEnumerable()
let rowCount = RowCount = dt.Rows.Count
let RowValues = (from column in dtPart.Columns.Cast<DataColumn>()
select row[column]).ToArray()
let decCount = RowCount = RowCount - 1
where dtPart.LoadDataRow(RowValues,LoadOption.OverwriteChanges) != default && decCount > 0
select dtPart).FirstOrDefault();
}
Currently we are doing this by looping through each value of list and dictionary:
private DataTable ChangeToDictionary(List<Dictionary<string,int>> list)
{
DataTable datatTableReturn = new DataTable();
if (list.Count() > 0)
{
Dictionary<string, int> haeders = list.ElementAt(0);
foreach (var colHead in haeders)
{
datatTableReturn.Columns.Add(colHead.Key);
}
}
foreach (var row in list)
{
DataRow dataRow = datatTableReturn.NewRow();
foreach (var col in row)
{
dataRow[col.Key] = col.Value;
}
datatTableReturn.Rows.Add(dataRow);
}
return datatTableReturn;
}
But is there a better way? Looping through so many times doesn't feel good
The answers above don't address the issue of the dictionary having more than 1 row. This solution addresses the issue.
static DataTable ToDataTable(List<Dictionary<string, int>> list)
{
DataTable result = new DataTable();
if (list.Count == 0)
return result;
var columnNames = list.SelectMany(dict=>dict.Keys).Distinct();
result.Columns.AddRange(columnNames.Select(c=>new DataColumn(c)).ToArray());
foreach (Dictionary<string,int> item in list)
{
var row = result.NewRow();
foreach (var key in item.Keys)
{
row[key] = item[key];
}
result.Rows.Add(row);
}
return result;
}
static void Main(string[] args)
{
List<Dictionary<string, int>> it = new List<Dictionary<string, int>>();
Dictionary<string, int> dict = new Dictionary<string, int>();
dict.Add("a", 1);
dict.Add("b", 2);
dict.Add("c", 3);
it.Add(dict);
dict = new Dictionary<string, int>();
dict.Add("bob", 34);
dict.Add("tom", 37);
it.Add(dict);
dict = new Dictionary<string, int>();
dict.Add("Yip Yip", 8);
dict.Add("Yap Yap", 9);
it.Add(dict);
DataTable table = ToDictionary(it);
foreach (DataColumn col in table.Columns)
Console.Write("{0}\t", col.ColumnName);
Console.WriteLine();
foreach (DataRow row in table.Rows)
{
foreach (DataColumn column in table.Columns)
Console.Write("{0}\t", row[column].ToString());
Console.WriteLine();
}
Console.ReadLine();
}
And the output looks like...
a b c bob tom Yip Yip Yap Yap
1 2 3
34 37
8 9
Speed, elegance and reusability don't go together. You always choose more important one, and try to balance other two.
Faster the code, uglier it is.
Prettier it is, less reusable it is.
Here's an example of "elegant" solution, but that goes with it not being very readable.
private static DataTable ToDictionary(List<Dictionary<string, int>> list)
{
DataTable result = new DataTable();
if (list.Count == 0)
return result;
result.Columns.AddRange(
list.First().Select(r => new DataColumn(r.Key)).ToArray()
);
list.ForEach(r => result.Rows.Add(r.Select(c => c.Value).Cast<object>().ToArray()));
return result;
}
Try this
List<Dictionary<string, object>> ListDic;
var stringListDic = JsonConvert.SerializeObject(ListDic);
var dataTable = JsonConvert.DeserializeObject<DataTable>(stringListDic);
Try this:
private DataTable GetDataTableFromDictionaries<T>(List<Dictionary<string, T>> list)
{
DataTable dataTable = new DataTable();
if (list == null || !list.Any()) return dataTable;
foreach (var column in list.First().Select(c => new DataColumn(c.Key, typeof(T))))
{
dataTable.Columns.Add(column);
}
foreach (var row in list.Select(
r =>
{
var dataRow = dataTable.NewRow();
r.ToList().ForEach(c => dataRow.SetField(c.Key, c.Value));
return dataRow;
}))
{
dataTable.Rows.Add(row);
}
return dataTable;
}
How about something like the code below?
Good, because it iterates each row exactly once. It should be pretty quick, I've included obvious exceptions to make the code safer.
private static DataTable DictionariesToDataTable<T>(
IEnumerable<IDictionary<string, T>> source)
{
if (source == null)
{
return null;
}
var result = new DataTable();
using (var e = source.GetEnumerator())
{
if (!e.MoveNext())
{
return result;
}
if (e.Current.Keys.Length == 0)
{
throw new InvalidOperationException();
}
var length = e.Current.Keys.Length;
result.Columns.AddRange(
e.Current.Keys.Select(k => new DataColumn(k, typeof(T))).ToArray());
do
{
if (e.Current.Values.Length != length)
{
throw new InvalidOperationException();
}
result.Rows.Add(e.Current.Values);
}
while (e.MoveNext());
return result;
}
}
try my solution, seems very clean to me:
private DataTable DictonarysToDataTable(List<Dictionary<string, int>> list)
{
DataTable table = new DataTable();
foreach (Dictionary<string,string> dict in list) //for every dictonary in the list ..
{
foreach (KeyValuePair<string,int> entry in dict) //for every entry in every dict
{
if (!myTable.Columns.Contains(entry.Key.ToString()))//if it doesn't exist yet
{
myTable.Columns.Add(entry.Key); //add all it's keys as columns to the table
}
}
table.Rows.Add(dict.Values.ToArray()); //add the the Values of every dict in the list as a new row
}
return table;
}
Edit:
Oh Snap, this works only for one Dictionary .. i didn't think it through.
But maybie you can modify it to work for a List of Dictionarys ..
Give this a try please
DataTable table = new DataTable();
foreach (IDictionary<string, object> row in DeviceTypeReport)
{
foreach (KeyValuePair<string, object> entry in row)
{
if (!table.Columns.Contains(entry.Key.ToString()))
{
table.Columns.Add(entry.Key);
}
}
table.Rows.Add(row.Values.ToArray());
}
private DataTable toDataTable(List<RetirementDiskModelDto> retirementDiskModelDtos)
{
DataTable result = new DataTable();
foreach (var col in retirementDiskModelDtos.FirstOrDefault().Items)
result.Columns.Add(col.Key);
foreach (var row in retirementDiskModelDtos)
{
DataRow newrow = result.NewRow();
foreach (var col in retirementDiskModelDtos.FirstOrDefault().Items)
newrow[col.Key] = col.Value;
result.Rows.Add(newrow);
}
return result;
}
i have a linq to dataTable query like this:
`var ShowResult = from r in Result.AsEnumerable()
where Convert.ToInt32(r.Field<double>("ASLVAM") / r.Field<double>("GEST")) > 60
orderby Convert.ToInt32(r.Field<double>("ASLVAM") / r.Field<double>("GEST")) descending
select new
{
pascode = r.Field<string>("PAS_CODE"),
melli = r.Field<string>("CODEMELI"),
name = r.Field<string>("NAM"),
family = r.Field<string>("FAMILY"),
bycode = r.Field<string>("BAYGANI"),
jancode = r.Field<string>("CODEJANBAZ"),
darsad = r.Field<int>("DARSAD"),
ostan = r.Field<string>("OSTAN_N"),
vacode = r.Field<string>("VA_CODE"),
moin = r.Field<string>("VA_MOIN"),
onvan = r.Field<string>("TAFZILI"),
aslvam = r.Field<double>("ASLVAM"),
gest = r.Field<double>("GEST"),
//tededGestKol = Convert.ToInt32(r.Field<double>("ASLVAM") / r.Field<double>("GEST")),
mandeVam = r.Field<double>("MANDE_VAM"),
dPardakht = r.Field<string>("DATE_P")
};`<code>
and i added reference System.Data.DataSetExtentions to use CopyToDataTable() method for showing my query result in a dataGrid view but this method didn,t add to my Inellisence,
I also use the MSDN Sample to use this method but this time i got this error :
"Specified Cast is not valid"
Please help me , what can i do to overcom this problem?
CopyToDataTable() only works when your query returns an IEnumerable<'DataRow>. In your query, you are returning an anonymous type. Anonymous types don't carry the extension method for CopyToDataTable(). You could just select the entire row like this, assuming Result is a DataTable. Then create your anonymous type.
public static void Start()
{
DataTable Result = new DataTable();
var ShowResult = from r in Result.AsEnumerable()
where Convert.ToInt32(r.Field<double>("ASLVAM") / r.Field<double>("GEST")) > 60
orderby Convert.ToInt32(r.Field<double>("ASLVAM") / r.Field<double>("GEST")) descending
select r;
DataTable newDataTbl = ShowResult.CopyToDataTable();
var anonType = newDataTbl.AsEnumerable()
.Select(r => new
{
pascode = r.Field<string>("PAS_CODE"),
melli = r.Field<string>("CODEMELI"),
name = r.Field<string>("NAM"),
family = r.Field<string>("FAMILY"),
bycode = r.Field<string>("BAYGANI"),
jancode = r.Field<string>("CODEJANBAZ"),
darsad = r.Field<int>("DARSAD"),
ostan = r.Field<string>("OSTAN_N"),
vacode = r.Field<string>("VA_CODE"),
moin = r.Field<string>("VA_MOIN"),
onvan = r.Field<string>("TAFZILI"),
aslvam = r.Field<double>("ASLVAM"),
gest = r.Field<double>("GEST"),
//tededGestKol = Convert.ToInt32(r.Field<double>("ASLVAM") / r.Field<double>("GEST")),
mandeVam = r.Field<double>("MANDE_VAM"),
dPardakht = r.Field<string>("DATE_P")
}
);
}
In lieu of the former method, you could use the following extension methods to create a Datatable from a List<'T>.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.ComponentModel;
using System.Reflection;
namespace Common
{
public static class DataTableExtensions
{
public static DataTable ConvertToDataTable<T>(this 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);
}
table.AcceptChanges();
return table;
}
public static DataRow ConvertToDataRow<T>(this T item, DataTable table)
{
PropertyDescriptorCollection properties =
TypeDescriptor.GetProperties(typeof(T));
DataRow row = table.NewRow();
foreach (PropertyDescriptor prop in properties)
row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
return row;
}
public static T ConvertToEntity<T>(this DataRow tableRow) where T : new()
{
// Create a new type of the entity I want
Type t = typeof(T);
T returnObject = new T();
foreach (DataColumn col in tableRow.Table.Columns)
{
string colName = col.ColumnName;
// Look for the object's property with the columns name, ignore case
PropertyInfo pInfo = t.GetProperty(colName.ToLower(),
BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance);
// did we find the property ?
if (pInfo != null)
{
object val = tableRow[colName];
// is this a Nullable<> type
bool IsNullable = (Nullable.GetUnderlyingType(pInfo.PropertyType) != null);
if (IsNullable)
{
if (val is System.DBNull)
{
val = null;
}
else
{
// Convert the db type into the T we have in our Nullable<T> type
val = Convert.ChangeType(val, Nullable.GetUnderlyingType(pInfo.PropertyType));
}
}
else
{
// Convert the db type into the type of the property in our entity
SetDefaultValue(ref val, pInfo.PropertyType);
if (pInfo.PropertyType.IsEnum && !pInfo.PropertyType.IsGenericType)
{
val = Enum.ToObject(pInfo.PropertyType, val);
}
else
val = Convert.ChangeType(val, pInfo.PropertyType);
}
// Set the value of the property with the value from the db
if (pInfo.CanWrite)
pInfo.SetValue(returnObject, val, null);
}
}
// return the entity object with values
return returnObject;
}
private static void SetDefaultValue(ref object val, Type propertyType)
{
if (val is DBNull)
{
val = GetDefault(propertyType);
}
}
public static object GetDefault(Type type)
{
if (type.IsValueType)
{
return Activator.CreateInstance(type);
}
return null;
}
public static List<T> ConvertToList<T>(this DataTable table) where T : new()
{
Type t = typeof(T);
// Create a list of the entities we want to return
List<T> returnObject = new List<T>();
// Iterate through the DataTable's rows
foreach (DataRow dr in table.Rows)
{
// Convert each row into an entity object and add to the list
T newRow = dr.ConvertToEntity<T>();
returnObject.Add(newRow);
}
// Return the finished list
return returnObject;
}
}
}
I have few methods that returns different Generic Lists.
Exists in .net any class static method or whatever to convert any list into a datatable? The only thing that i can imagine is use Reflection to do this.
IF i have this:
List<Whatever> whatever = new List<Whatever>();
(This next code doesn't work of course, but i would like to have the possibility of:
DataTable dt = (DataTable) whatever;
Here's a nice 2013 update using FastMember from NuGet:
IEnumerable<SomeType> data = ...
DataTable table = new DataTable();
using(var reader = ObjectReader.Create(data)) {
table.Load(reader);
}
This uses FastMember's meta-programming API for maximum performance. If you want to restrict it to particular members (or enforce the order), then you can do that too:
IEnumerable<SomeType> data = ...
DataTable table = new DataTable();
using(var reader = ObjectReader.Create(data, "Id", "Name", "Description")) {
table.Load(reader);
}
Editor's Dis/claimer: FastMember is a Marc Gravell project. It's gold and full-on flies!
Yes, this is pretty much the exact opposite of this one; reflection would suffice - or if you need quicker, HyperDescriptor in 2.0, or maybe Expression in 3.5. Actually, HyperDescriptor should be more than adequate.
For example:
// remove "this" if not on C# 3.0 / .NET 3.5
public static DataTable ToDataTable<T>(this IList<T> data)
{
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, prop.PropertyType);
}
object[] values = new object[props.Count];
foreach (T item in data)
{
for (int i = 0; i < values.Length; i++)
{
values[i] = props[i].GetValue(item);
}
table.Rows.Add(values);
}
return table;
}
Now with one line you can make this many many times faster than reflection (by enabling HyperDescriptor for the object-type T).
Edit re performance query; here's a test rig with results:
Vanilla 27179
Hyper 6997
I suspect that the bottleneck has shifted from member-access to DataTable performance... I doubt you'll improve much on that...
Code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
public class MyData
{
public int A { get; set; }
public string B { get; set; }
public DateTime C { get; set; }
public decimal D { get; set; }
public string E { get; set; }
public int F { get; set; }
}
static class Program
{
static void RunTest(List<MyData> data, string caption)
{
GC.Collect(GC.MaxGeneration, GCCollectionMode.Forced);
GC.WaitForPendingFinalizers();
GC.WaitForFullGCComplete();
Stopwatch watch = Stopwatch.StartNew();
for (int i = 0; i < 500; i++)
{
data.ToDataTable();
}
watch.Stop();
Console.WriteLine(caption + "\t" + watch.ElapsedMilliseconds);
}
static void Main()
{
List<MyData> foos = new List<MyData>();
for (int i = 0 ; i < 5000 ; i++ ){
foos.Add(new MyData
{ // just gibberish...
A = i,
B = i.ToString(),
C = DateTime.Now.AddSeconds(i),
D = i,
E = "hello",
F = i * 2
});
}
RunTest(foos, "Vanilla");
Hyper.ComponentModel.HyperTypeDescriptionProvider.Add(
typeof(MyData));
RunTest(foos, "Hyper");
Console.ReadLine(); // return to exit
}
}
I had to modify Marc Gravell's sample code to handle nullable types and null values. I have included a working version below. Thanks Marc.
public static DataTable ToDataTable<T>(this 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;
}
This is a simple mix of the solutions.
It work with Nullable types.
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;
}
A small change to Marc's answer to make it work with value types like List<string> to data table:
public static DataTable ListToDataTable<T>(IList<T> data)
{
DataTable table = new DataTable();
//special handling for value types and string
if (typeof(T).IsValueType || typeof(T).Equals(typeof(string)))
{
DataColumn dc = new DataColumn("Value", typeof(T));
table.Columns.Add(dc);
foreach (T item in data)
{
DataRow dr = table.NewRow();
dr[0] = item;
table.Rows.Add(dr);
}
}
else
{
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(typeof(T));
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)
{
try
{
row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
}
catch (Exception ex)
{
row[prop.Name] = DBNull.Value;
}
}
table.Rows.Add(row);
}
}
return table;
}
Another approach is the above:
List<WhateEver> lst = getdata();
string json = Newtonsoft.Json.JsonConvert.SerializeObject(lst);
DataTable pDt = JsonConvert.DeserializeObject<DataTable>(json);
This link on MSDN is worth a visit: How to: Implement CopyToDataTable<T> Where the Generic Type T Is Not a DataRow
This adds an extension method that lets you do this:
// Create a sequence.
Item[] items = new Item[]
{ new Book{Id = 1, Price = 13.50, Genre = "Comedy", Author = "Gustavo Achong"},
new Book{Id = 2, Price = 8.50, Genre = "Drama", Author = "Jessie Zeng"},
new Movie{Id = 1, Price = 22.99, Genre = "Comedy", Director = "Marissa Barnes"},
new Movie{Id = 1, Price = 13.40, Genre = "Action", Director = "Emmanuel Fernandez"}};
// Query for items with price greater than 9.99.
var query = from i in items
where i.Price > 9.99
orderby i.Price
select i;
// Load the query results into new DataTable.
DataTable table = query.CopyToDataTable();
List<YourModel> data = new List<YourModel>();
DataTable dataTable = Newtonsoft.Json.JsonConvert.DeserializeObject<DataTable>(Newtonsoft.Json.JsonConvert.SerializeObject(data));
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;
}
try this
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;
}
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.
Marc Gravell's answer but in VB.NET
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
To Convert Generic list into DataTable
using Newtonsoft.Json;
public DataTable GenericToDataTable(IList<T> list)
{
var json = JsonConvert.SerializeObject(list);
DataTable dt = (DataTable)JsonConvert.DeserializeObject(json, (typeof(DataTable)));
return dt;
}
I've written a small library myself to accomplish this task. It uses reflection only for the first time an object type is to be translated to a datatable. It emits a method that will do all the work translating an object type.
Its blazing fast. You can find it here:
ToDataTable() in MoreLinq on GitHub
original: ModelShredder on GoogleCode, was merged into MoreLinq, which moved from GoogleCode to GitHub
A 2019 answer if you're using .NET Core - use the Nuget ToDataTable library. Advantages:
Better performance than FastMember
Also creates structured SqlParameters for use as SQL Server Table-Valued Parameters
Disclaimer - I'm the author of ToDataTable
Performance - I span up some Benchmark .Net tests and included them in the ToDataTable repo. The results were as follows:
Creating a 100,000 Row Datatable:
MacOS Windows
Reflection 818.5 ms 818.3 ms
FastMember from 1105.5 ms 976.4 ms
Mark's answer
Improved FastMember 524.6 ms 456.4 ms
ToDataTable 449.0 ms 376.5 ms
The FastMember method suggested in Marc's answer seemed to perform worse than Mary's answer which used reflection, but I rolled another method using a FastMember TypeAccessor and it performed much better. Nevertheless the ToDataTable package outperformed the lot.
I also had to come up with an alternate solution, as none of the options listed here worked in my case. I was using an IEnumerable which returned an IEnumerable and the properties couldn't be enumerated. This did the trick:
// remove "this" if not on C# 3.0 / .NET 3.5
public static DataTable ConvertToDataTable<T>(this IEnumerable<T> data)
{
List<IDataRecord> list = data.Cast<IDataRecord>().ToList();
PropertyDescriptorCollection props = null;
DataTable table = new DataTable();
if (list != null && list.Count > 0)
{
props = TypeDescriptor.GetProperties(list[0]);
for (int i = 0; i < props.Count; i++)
{
PropertyDescriptor prop = props[i];
table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
}
}
if (props != null)
{
object[] values = new object[props.Count];
foreach (T item in data)
{
for (int i = 0; i < values.Length; i++)
{
values[i] = props[i].GetValue(item) ?? DBNull.Value;
}
table.Rows.Add(values);
}
}
return table;
}
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;
}
}
I realize that this has been closed for a while; however, I had a solution to this specific problem but needed a slight twist: the columns and data table needed to be predefined / already instantiated. Then I needed to simply insert the types into the data table.
So here's an example of what I did:
public static class Test
{
public static void Main()
{
var dataTable = new System.Data.DataTable(Guid.NewGuid().ToString());
var columnCode = new DataColumn("Code");
var columnLength = new DataColumn("Length");
var columnProduct = new DataColumn("Product");
dataTable.Columns.AddRange(new DataColumn[]
{
columnCode,
columnLength,
columnProduct
});
var item = new List<SomeClass>();
item.Select(data => new
{
data.Id,
data.Name,
data.SomeValue
}).AddToDataTable(dataTable);
}
}
static class Extensions
{
public static void AddToDataTable<T>(this IEnumerable<T> enumerable, System.Data.DataTable table)
{
if (enumerable.FirstOrDefault() == null)
{
table.Rows.Add(new[] {string.Empty});
return;
}
var properties = enumerable.FirstOrDefault().GetType().GetProperties();
foreach (var item in enumerable)
{
var row = table.NewRow();
foreach (var property in properties)
{
row[property.Name] = item.GetType().InvokeMember(property.Name, BindingFlags.GetProperty, null, item, null);
}
table.Rows.Add(row);
}
}
}
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;
}
If you are using VB.NET then this class does the job.
Imports System.Reflection
''' <summary>
''' Convert any List(Of T) to a DataTable with correct column types and converts Nullable Type values to DBNull
''' </summary>
Public Class ConvertListToDataset
Public Function ListToDataset(Of T)(ByVal list As IList(Of T)) As DataTable
Dim dt As New DataTable()
'/* Create the DataTable columns */
For Each pi As PropertyInfo In GetType(T).GetProperties()
If pi.PropertyType.IsValueType Then
Debug.Print(pi.Name)
End If
If IsNothing(Nullable.GetUnderlyingType(pi.PropertyType)) Then
dt.Columns.Add(pi.Name, pi.PropertyType)
Else
dt.Columns.Add(pi.Name, Nullable.GetUnderlyingType(pi.PropertyType))
End If
Next
'/* Populate the DataTable with the values in the Items in List */
For Each item As T In list
Dim dr As DataRow = dt.NewRow()
For Each pi As PropertyInfo In GetType(T).GetProperties()
dr(pi.Name) = IIf(IsNothing(pi.GetValue(item)), DBNull.Value, pi.GetValue(item))
Next
dt.Rows.Add(dr)
Next
Return dt
End Function
End Class
if you have properties in your class this line of code is OK !!
PropertyDescriptorCollection props =
TypeDescriptor.GetProperties(typeof(T));
but if you have all public fields then use this:
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;
}
the original answer is from above , I just edited to use fields instead of properties
and to use it do this
DataTable dt = new DataTable();
dt = ToDataTable(myBriefs);
gridData.DataSource = dt;
gridData.DataBind();
To convert a generic list to data table, you could use the DataTableGenerator
This library lets you convert your list into a data table with multi-feature like
Translate data table header
specify some column to show
You can try something like below
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;
}
This is the simple Console Application to convert List to Datatable.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.ComponentModel;
namespace ConvertListToDataTable
{
public static class Program
{
public static void Main(string[] args)
{
List<MyObject> list = new List<MyObject>();
for (int i = 0; i < 5; i++)
{
list.Add(new MyObject { Sno = i, Name = i.ToString() + "-KarthiK", Dat = DateTime.Now.AddSeconds(i) });
}
DataTable dt = ConvertListToDataTable(list);
foreach (DataRow row in dt.Rows)
{
Console.WriteLine();
for (int x = 0; x < dt.Columns.Count; x++)
{
Console.Write(row[x].ToString() + " ");
}
}
Console.ReadLine();
}
public class MyObject
{
public int Sno { get; set; }
public string Name { get; set; }
public DateTime Dat { get; set; }
}
public static DataTable ConvertListToDataTable<T>(this List<T> iList)
{
DataTable dataTable = new DataTable();
PropertyDescriptorCollection props = TypeDescriptor.GetProperties(typeof(T));
for (int i = 0; i < props.Count; i++)
{
PropertyDescriptor propertyDescriptor = props[i];
Type type = propertyDescriptor.PropertyType;
if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
type = Nullable.GetUnderlyingType(type);
dataTable.Columns.Add(propertyDescriptor.Name, type);
}
object[] values = new object[props.Count];
foreach (T iListItem in iList)
{
for (int i = 0; i < values.Length; i++)
{
values[i] = props[i].GetValue(iListItem);
}
dataTable.Rows.Add(values);
}
return dataTable;
}
}
}
Dim counties As New List(Of County)
Dim dtCounties As DataTable
dtCounties = _combinedRefRepository.Get_Counties()
If dtCounties.Rows.Count <> 0 Then
For Each row As DataRow In dtCounties.Rows
Dim county As New County
county.CountyId = row.Item(0).ToString()
county.CountyName = row.Item(1).ToString().ToUpper()
counties.Add(county)
Next
dtCounties.Dispose()
End If
I think it's more convenient and easy to use.
List<Whatever> _lobj= new List<Whatever>();
var json = JsonConvert.SerializeObject(_lobj);
DataTable dt = (DataTable)JsonConvert.DeserializeObject(json, (typeof(DataTable)));
If you want to use reflection and set columns order/ include only some columns/ Exclude some columns try this:
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++;
}
}
List<object> Basket;
string json = JsonConvert.SerializeObject(Basket, Formatting.Indented);
DataTable dtUsingMethod = Business.GetJSONToDataTableUsingNewtonSoftDll(json);
public static DataTable GetJSONToDataTableUsingNewtonSoftDll(string JSONData)
{
DataTable dt = (DataTable)JsonConvert.DeserializeObject(JSONData, (typeof(DataTable)));
return dt;
}
Here is another one to the list. Cinchoo ETL - an open source library to convert enumerable to datatable.
List<Whatever> whatever = new List<Whatever>();
var dt = whatever.AsDataTable();
Disclaimer: I'm author of this library.