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How do I use reflection to dynamically call a type?

I have a DataGrid and I need to convert it to a DataTable. The problem is that I need To be able to get the type of my DataSource dynamically. The grid DataSource is of type 'Observable' which is a class I have in my project, but my task is to be able to dynamically create the DataTable without needing to specify the type only using the DataSource. How can I generate a method that I can use to place in <T> without getting the error " 'mytype' is a variable but is used like a type" .
Type mytype = Grid_Job.DataSource.GetType();
DataTable dt = CreateDataTable<mytype>((IEnumerable<mytype>)Grid_Job.DataSource);
public static DataTable CreateDataTable<T>(IEnumerable<T> list)
{
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 list)
{
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;
}
My Observable class is
public class Observable
{
public int JobNo { get; set; }
public string JobName { get; set; }
public string JobDescription { get; set; }
public string Job_Type { get; set; }
public string Job_Status { get; set; }
}

Effectively, you need to discard the generics and think in terms of the collection at runtime - discovering the element type itself. For example:
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Data;
using System.Reflection;
static class P
{
static object GetData()
=> new ObservableCollection<Observable>
{
new Observable { JobName = "abc", JobNo = 123 },
new Observable { JobName = "def", JobNo = 456 },
new Observable { JobName = "ghi", JobNo = 789 },
};
static void Main()
{
// note that we don't know *anything* about the data source here
object dataSource = GetData();
DataTable dt = CreateDataTable((IEnumerable)dataSource);
foreach (DataColumn col in dt.Columns)
{
Console.Write(col.ColumnName);
Console.Write("\t");
}
Console.WriteLine();
foreach (DataRow row in dt.Rows)
{
foreach (DataColumn col in dt.Columns)
{
Console.Write(row[col]);
Console.Write("\t");
}
Console.WriteLine();
}
}
public static DataTable CreateDataTable(IEnumerable list)
{
Type type = GetElementType(list.GetType());
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));
}
object[] values = new object[properties.Length];
foreach (object entity in list)
{
for (int i = 0; i < properties.Length; i++)
{
values[i] = properties[i].GetValue(entity);
}
dataTable.Rows.Add(values);
}
return dataTable;
}
static Type GetElementType(Type type)
{
foreach (Type interfaceType in type.GetInterfaces())
{
if (interfaceType.IsGenericType &&
interfaceType.GetGenericTypeDefinition()
== typeof(IList<>))
{
return type.GetGenericArguments()[0];
}
}
return null;
}
}
public class Observable
{
public int JobNo { get; set; }
public string JobName { get; set; }
public string JobDescription { get; set; }
public string Job_Type { get; set; }
public string Job_Status { get; set; }
}
Note that in some cases you should prefer the TypeDescriptor model over reflection, as this allows runtime definition of properties; this is a niche area and probably doesn't apply to you, but it relevant to know about. As an example, this is how DataTable itself chooses to expose the properties it has as discoverable at runtime to general purpose tools. There are also a few list indirection APIs that need to be considered in those cases.

C# complex class to SQLBulkInsert millions or rows

I'm having an issue, apparently is very simple but I haven't found anything related.
public class Fruit
{
public string name { get; set; }
public string color { get; set; }
public string shape { get; set; }
public Image image { get; set; }
}
public class Image
{
public string Id { get; set; }
public string URL { get; set; }
}
That's my "complex" class, and I want to convert this to DataTable to apply the SQLBulkCopy but when it retrieves the Image class it's not bringing the values but the data type "Image" which throws an exception.
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;
}
Any clue on how can I retrieve the ID for the Image property to do the SQLBulkCopy?
By the way, this is the method I'm using for the insert:
public static void SaveToDatabase(DataTable data)
{
using (var connection = new SqlConnection(dbConn))
{
SqlTransaction transaction = null;
connection.Open();
try
{
transaction = connection.BeginTransaction();
using (var sqlBulkCopy = new SqlBulkCopy(connection, SqlBulkCopyOptions.TableLock, transaction))
{
sqlBulkCopy.DestinationTableName = "Fruit";
sqlBulkCopy.ColumnMappings.Add("name", "name");
sqlBulkCopy.ColumnMappings.Add("color", "color");
sqlBulkCopy.ColumnMappings.Add("shape", "shape");
sqlBulkCopy.ColumnMappings.Add("image", "image");
sqlBulkCopy.WriteToServer(data);
}
transaction.Commit();
}
catch (Exception ex) // Here I got the datatype Exception because I don't know how to get the Image.ID value
{
transaction.Rollback();
}
}
}
Apparently my post it's a little bit confusing, so I'm going to add the issue here:
How to get the URL and ID values from the Image class in the following code? Currently, it's bringing the object Image which it's unknown and throws an exception
sqlBulkCopy.ColumnMappings.Add("image", "image");
How can I map them? I know I can do it row by row, but I have more than 2 million rows to process on each execution. That's why I'm trying to use the bulkcopy.
I need to add that this data comes from an API call in Json format

After modifying the code to test this I did find a solution:
if (prop.GetChildProperties().Count > 1)
row[prop.Name] = (Image)prop.GetValue(item);
else
row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
The solution was only to cast the GetValue to the Image class, this was applied in the ToDataTable method:
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)
if (prop.GetChildProperties().Count > 1)
row[prop.Name] = (Image)prop.GetValue(item);
else
row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
table.Rows.Add(row);
}
return table;
}
Thank you all for your time and help!

How to convert a list of model to multidimensional array c#

this the problem; I have a list and I would like to covert to a multidimencion array, this is the class:
public class Student{
public int Id {get; set;}
public string name {get; set;}
public string name {get; set;}
}
the list is, (I am using EF);
var listStudent = db.Students.ToList();
I would to converte this list to something like this
string[,] new Value= db.Students.ToList();

In the controller, you do something like:
Student student1 = new Student();
Student student2 = new Student();
string[,] temp = {
{ student1.FirstName, student1.LastName },
{ student2.FirstName, student2.LastName }
};
By the way, you should provide more details.

I resolved,
My idea was, how to convert a list of any object to a multidimensional array, something like this:
1.- First my class:
public class Myclass{
public string propr1 { get; set;}
public string propr2 { get; set;}
public string propr3 { get; set;}
}
2.- Make query using EF:
var listMyclass = db.Myclass.ToList();
3.- Use this method to convert this list to DataTable:
public DataTable ToDataTable<T>(List<T> items)
{
DataTable dataTable = new DataTable(typeof(T).Name);
//Get all the properties by using reflection
PropertyInfo[] Props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (PropertyInfo prop in Props)
{
//Setting column names as Property names
dataTable.Columns.Add(prop.Name);
}
foreach (T item in items)
{
var values = new object[Props.Length];
for (int i = 0; i < Props.Length; i++)
{
values[i] = Props[i].GetValue(item, null);
}
dataTable.Rows.Add(values);
}
return dataTable;
}
4.- get DataTable:
DataTable dt = ToDataTable<T>(listMyclass);
5.- And finally, pass all values from DataTable to multidimensional Array:
string[,] multidimensionalArray = new string[dt.Rows.Count, dt.Columns.Count];
for (int i = 0; i < dt.Rows.Count; i++)
{
for (int j = 0; j < dt.Columns.Count; j++)
{
multidimensionalArray[i, j] = dt.Rows[i][j].ToString();
}
}
Thank you all..!!

Filter complex objects in DataTable/DataView

I want to filter a DataTable or DaatView that contains complex objects.
Let's say I have this object Person
public class Person{
public int Id{get; set;}
public int Age{get; set;}
public strng Name{get; set;}
public Address BillAddress{get; set;}
}
public class Address{
public string
Town{get; set}
public string Street{get; set}
public int Number{get; set}
}
Now i fill a DataView with a list of Person objects:
public static DataView ToObjectDataView<T>(this IList<T> list, int countOfColumns)
{
if (list == null || countOfColumns < 1)
{
return null;
}
int columns = countOfColumns;
DataTable dataTable = new DataTable();
for (int currentCol = 0; currentCol != columns; currentCol++)
{
DataColumn column = new DataColumn(currentCol.ToString(), typeof(T));
dataTable.Columns.Add(column);
}
DataRow row = null;
int currentColumn = 0;
for (int index = 0; index < list.Count; index++)
{
if (list[index] == null)
{
continue;
}
if (Equals(null, row))
row = dataTable.NewRow();
row[currentColumn] = list[index];
currentColumn++;
if (currentColumn == columns)
{
dataTable.Rows.Add(row);
row = null;
currentColumn = 0;
}
}
//Verarbeitung der letzten Zeile
if (!Equals(null, row))
{
dataTable.Rows.Add(row);
}
return new DataView(dataTable);
}
So that i get a DataView with 10 columns of Person objects, evrey column has the name of its index:
IList<Person> personList = new List<Person>();
// Fill the list...
DataView dataSource = personList.ToObjectDataSource(10);
Now I would like to filter this DataView based on child values with an expression, for example, get all persons that live in the 'Fakestreet'.
I tried "0.BillAddress.Street = 'Fakestreet'"(and or expression with the rest columns) but that doesn't work..

This is a partial solution, because I didn't find a direct way.
Use the DataTable AsEnumerable extension and filter with dynamic linq (System.Linq.Dynamic (also available for .Net 3.5))
// Filter directly the List
public static List<T> FilterByLinqExpression<T>(this IList<T> list, string linqFilterExpression)
{
var result = list.AsQueryable().Where(linqFilterExpression);
return result.ToList<T>();
}
So you can call it like this for all persons that live in a street that has 'Avenue' in it's name:
IList<Person> personList = new List<Person>();
// Fill the list...
var filteredValues = personList.FilterByLinqExpression("((BillAddress.Street).Contains(\"Avenue\"))");
DataView dataSource = filteredValues .ToObjectDataSource(10);
I use this to filter for example complex objects that are used to be displayed in a DevExpress ASPxGridView. By the way, they have an automatic converter from their filter expressions to different filter expression, in my case the 'CriteriaToWhereClauseHelper.GetDynamicLinqWhere()' that converts the given filter expression to a dynamic linq expression.

How do you convert a DataTable into a generic list?

Currently, I'm using:
DataTable dt = CreateDataTableInSomeWay();
List<DataRow> list = new List<DataRow>();
foreach (DataRow dr in dt.Rows)
{
list.Add(dr);
}
Is there a better/magic way?

If you're using .NET 3.5, you can use DataTableExtensions.AsEnumerable (an extension method) and then if you really need a List<DataRow> instead of just IEnumerable<DataRow> you can call Enumerable.ToList:
IEnumerable<DataRow> sequence = dt.AsEnumerable();
or
using System.Linq;
...
List<DataRow> list = dt.AsEnumerable().ToList();

List<Employee> emp = new List<Employee>();
//Maintaining DataTable on ViewState
//For Demo only
DataTable dt = ViewState["CurrentEmp"] as DataTable;
//read data from DataTable
//using lamdaexpression
emp = (from DataRow row in dt.Rows
select new Employee
{
_FirstName = row["FirstName"].ToString(),
_LastName = row["Last_Name"].ToString()
}).ToList();

With C# 3.0 and System.Data.DataSetExtensions.dll,
List<DataRow> rows = table.Rows.Cast<DataRow>().ToList();

You could use
List<DataRow> list = new List<DataRow>(dt.Select());
dt.Select() will return all rows in your table, as an array of datarows, and the List constructor accepts that array of objects as an argument to initially fill your list with.

If you just want a list of values from the "ID" int field returned, you could use...
List<int> ids = (from row in dt.AsEnumerable() select Convert.ToInt32(row["ID"])).ToList();

You can create a extension function as :
public static List<T> ToListof<T>(this DataTable dt)
{
const BindingFlags flags = BindingFlags.Public | BindingFlags.Instance;
var columnNames = dt.Columns.Cast<DataColumn>()
.Select(c => c.ColumnName)
.ToList();
var objectProperties = typeof(T).GetProperties(flags);
var targetList = dt.AsEnumerable().Select(dataRow =>
{
var instanceOfT = Activator.CreateInstance<T>();
foreach (var properties in objectProperties.Where(properties => columnNames.Contains(properties.Name) && dataRow[properties.Name] != DBNull.Value))
{
properties.SetValue(instanceOfT, dataRow[properties.Name], null);
}
return instanceOfT;
}).ToList();
return targetList;
}
var output = yourDataInstance.ToListof<targetModelType>();

I have added some modification to the code from this answer (https://stackoverflow.com/a/24588210/4489664) because for nullable Types it will return exception
public static List<T> DataTableToList<T>(this DataTable table) where T: new()
{
List<T> list = new List<T>();
var typeProperties = typeof(T).GetProperties().Select(propertyInfo => new
{
PropertyInfo = propertyInfo,
Type = Nullable.GetUnderlyingType(propertyInfo.PropertyType) ?? propertyInfo.PropertyType
}).ToList();
foreach (var row in table.Rows.Cast<DataRow>())
{
T obj = new T();
foreach (var typeProperty in typeProperties)
{
object value = row[typeProperty.PropertyInfo.Name];
object safeValue = value == null || DBNull.Value.Equals(value)
? null
: Convert.ChangeType(value, typeProperty.Type);
typeProperty.PropertyInfo.SetValue(obj, safeValue, null);
}
list.Add(obj);
}
return list;
}

using System.Data;
var myEnumerable = myDataTable.AsEnumerable();
List<MyClass> myClassList =
(from item in myEnumerable
select new MyClass{
MyClassProperty1 = item.Field<string>("DataTableColumnName1"),
MyClassProperty2 = item.Field<string>("DataTableColumnName2")
}).ToList();

Again, using 3.5 you may do it like:
dt.Select().ToList()
BRGDS

// this is better suited for expensive object creation/initialization
IEnumerable<Employee> ParseEmployeeTable(DataTable dtEmployees)
{
var employees = new ConcurrentBag<Employee>();
Parallel.ForEach(dtEmployees.AsEnumerable(), (dr) =>
{
employees.Add(new Employee()
{
_FirstName = dr["FirstName"].ToString(),
_LastName = dr["Last_Name"].ToString()
});
});
return employees;
}

A more 'magic' way, and doesn't need .NET 3.5.
If, for example, DBDatatable was returning a single column of Guids (uniqueidentifier in SQL) then you could use:
Dim gList As New List(Of Guid)
gList.AddRange(DirectCast(DBDataTable.Select(), IEnumerable(Of Guid)))

DataTable dt; // datatable should contains datacolumns with Id,Name
List<Employee> employeeList=new List<Employee>(); // Employee should contain EmployeeId, EmployeeName as properties
foreach (DataRow dr in dt.Rows)
{
employeeList.Add(new Employee{EmployeeId=dr.Id,EmplooyeeName=dr.Name});
}

The Easiest way of Converting the DataTable into the Generic list of class
using Newtonsoft.Json;
var json = JsonConvert.SerializeObject(dataTable);
var model = JsonConvert.DeserializeObject<List<ClassName>>(json);

DataTable.Select() doesnt give the Rows in the order they were present in the datatable.
If order is important I feel iterating over the datarow collection and forming a List is the right way to go or you could also use overload of DataTable.Select(string filterexpression, string sort).
But this overload may not handle all the ordering (like order by case ...) that SQL provides.

/* This is a generic method that will convert any type of DataTable to a List
*
*
* Example : List< Student > studentDetails = new List< Student >();
* studentDetails = ConvertDataTable< Student >(dt);
*
* Warning : In this case the DataTable column's name and class property name
* should be the same otherwise this function will not work properly
*/
The following are the two functions in which if we pass a
DataTable
and a user defined class.
It will then return the List of that class with the DataTable data.
public static List<T> ConvertDataTable<T>(DataTable dt)
{
List<T> data = new List<T>();
foreach (DataRow row in dt.Rows)
{
T item = GetItem<T>(row);
data.Add(item);
}
return data;
}
private static T GetItem<T>(DataRow dr)
{
Type temp = typeof(T);
T obj = Activator.CreateInstance<T>();
foreach (DataColumn column in dr.Table.Columns)
{
foreach (PropertyInfo pro in temp.GetProperties())
{
//in case you have a enum/GUID datatype in your model
//We will check field's dataType, and convert the value in it.
if (pro.Name == column.ColumnName){
try
{
var convertedValue = GetValueByDataType(pro.PropertyType, dr[column.ColumnName]);
pro.SetValue(obj, convertedValue, null);
}
catch (Exception e)
{
//ex handle code
throw;
}
//pro.SetValue(obj, dr[column.ColumnName], null);
}
else
continue;
}
}
return obj;
}
This method will check the datatype of field, and convert dataTable value in to that datatype.
private static object GetValueByDataType(Type propertyType, object o)
{
if (o.ToString() == "null")
{
return null;
}
if (propertyType == (typeof(Guid)) || propertyType == typeof(Guid?))
{
return Guid.Parse(o.ToString());
}
else if (propertyType == typeof(int) || propertyType.IsEnum)
{
return Convert.ToInt32(o);
}
else if (propertyType == typeof(decimal) )
{
return Convert.ToDecimal(o);
}
else if (propertyType == typeof(long))
{
return Convert.ToInt64(o);
}
else if (propertyType == typeof(bool) || propertyType == typeof(bool?))
{
return Convert.ToBoolean(o);
}
else if (propertyType == typeof(DateTime) || propertyType == typeof(DateTime?))
{
return Convert.ToDateTime(o);
}
return o.ToString();
}
To call the preceding method, use the following syntax:
List< Student > studentDetails = new List< Student >();
studentDetails = ConvertDataTable< Student >(dt);
Change the Student class name and dt value based on your requirements. In this case the DataTable column's name and class property name should be the same otherwise this function will not work properly.

lPerson = dt.AsEnumerable().Select(s => new Person()
{
Name = s.Field<string>("Name"),
SurName = s.Field<string>("SurName"),
Age = s.Field<int>("Age"),
InsertDate = s.Field<DateTime>("InsertDate")
}).ToList();
Link to working DotNetFiddle Example
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Data.DataSetExtensions;
public static void Main()
{
DataTable dt = new DataTable();
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("SurName", typeof(string));
dt.Columns.Add("Age", typeof(int));
dt.Columns.Add("InsertDate", typeof(DateTime));
var row1= dt.NewRow();
row1["Name"] = "Adam";
row1["SurName"] = "Adam";
row1["Age"] = 20;
row1["InsertDate"] = new DateTime(2020, 1, 1);
dt.Rows.Add(row1);
var row2 = dt.NewRow();
row2["Name"] = "John";
row2["SurName"] = "Smith";
row2["Age"] = 25;
row2["InsertDate"] = new DateTime(2020, 3, 12);
dt.Rows.Add(row2);
var row3 = dt.NewRow();
row3["Name"] = "Jack";
row3["SurName"] = "Strong";
row3["Age"] = 32;
row3["InsertDate"] = new DateTime(2020, 5, 20);
dt.Rows.Add(row3);
List<Person> lPerson = new List<Person>();
lPerson = dt.AsEnumerable().Select(s => new Person()
{
Name = s.Field<string>("Name"),
SurName = s.Field<string>("SurName"),
Age = s.Field<int>("Age"),
InsertDate = s.Field<DateTime>("InsertDate")
}).ToList();
foreach(Person pers in lPerson)
{
Console.WriteLine("{0} {1} {2} {3}", pers.Name, pers.SurName, pers.Age, pers.InsertDate);
}
}
public class Person
{
public string Name { get; set; }
public string SurName { get; set; }
public int Age { get; set; }
public DateTime InsertDate { get; set; }
}
}

Use System.Data namespace then you will get .AsEnumerable().

This worked for me:
Need at least .Net Framework 3.5,
Code below displays DataRow turned to Generic.IEnumerable, comboBox1 has been used for a better illustration.
using System.Linq;
DataTable dt = new DataTable();
dt = myClass.myMethod();
List<object> list = (from row in dt.AsEnumerable() select (row["name"])).ToList();
comboBox1.DataSource = list;

Output
public class ModelUser
{
#region Model
private string _username;
private string _userpassword;
private string _useremail;
private int _userid;
/// <summary>
///
/// </summary>
public int userid
{
set { _userid = value; }
get { return _userid; }
}
/// <summary>
///
/// </summary>
public string username
{
set { _username = value; }
get { return _username; }
}
/// <summary>
///
/// </summary>
public string useremail
{
set { _useremail = value; }
get { return _useremail; }
}
/// <summary>
///
/// </summary>
public string userpassword
{
set { _userpassword = value; }
get { return _userpassword; }
}
#endregion Model
}
public List<ModelUser> DataTableToList(DataTable dt)
{
List<ModelUser> modelList = new List<ModelUser>();
int rowsCount = dt.Rows.Count;
if (rowsCount > 0)
{
ModelUser model;
for (int n = 0; n < rowsCount; n++)
{
model = new ModelUser();
model.userid = (int)dt.Rows[n]["userid"];
model.username = dt.Rows[n]["username"].ToString();
model.useremail = dt.Rows[n]["useremail"].ToString();
model.userpassword = dt.Rows[n]["userpassword"].ToString();
modelList.Add(model);
}
}
return modelList;
}
static DataTable GetTable()
{
// Here we create a DataTable with four columns.
DataTable table = new DataTable();
table.Columns.Add("userid", typeof(int));
table.Columns.Add("username", typeof(string));
table.Columns.Add("useremail", typeof(string));
table.Columns.Add("userpassword", typeof(string));
// Here we add five DataRows.
table.Rows.Add(25, "Jame", "Jame#hotmail.com", DateTime.Now.ToString());
table.Rows.Add(50, "luci", "luci#hotmail.com", DateTime.Now.ToString());
table.Rows.Add(10, "Andrey", "Andrey#hotmail.com", DateTime.Now.ToString());
table.Rows.Add(21, "Michael", "Michael#hotmail.com", DateTime.Now.ToString());
table.Rows.Add(100, "Steven", "Steven#hotmail.com", DateTime.Now.ToString());
return table;
}
protected void Page_Load(object sender, EventArgs e)
{
List<ModelUser> userList = new List<ModelUser>();
DataTable dt = GetTable();
userList = DataTableToList(dt);
gv.DataSource = userList;
gv.DataBind();
}[enter image description here][1]
</asp:GridView>
</div>

We can use a Generic Method for converting DataTable to List instead of manually converting a DataTable to List.
Note: DataTable's ColumnName and Type's PropertyName should be same.
Call the below Method:
long result = Utilities.ConvertTo<Student>(dt ,out listStudent);
// Generic Method
public class Utilities
{
public static long ConvertTo<T>(DataTable table, out List<T> entity)
{
long returnCode = -1;
entity = null;
if (table == null)
{
return -1;
}
try
{
entity = ConvertTo<T>(table.Rows);
returnCode = 0;
}
catch (Exception ex)
{
returnCode = 1000;
}
return returnCode;
}
static List<T> ConvertTo<T>(DataRowCollection rows)
{
List<T> list = null;
if (rows != null)
{
list = new List<T>();
foreach (DataRow row in rows)
{
T item = CreateItem<T>(row);
list.Add(item);
}
}
return list;
}
static T CreateItem<T>(DataRow row)
{
string str = string.Empty;
string strObj = string.Empty;
T obj = default(T);
if (row != null)
{
obj = Activator.CreateInstance<T>();
strObj = obj.ToString();
NameValueCollection objDictionary = new NameValueCollection();
foreach (DataColumn column in row.Table.Columns)
{
PropertyInfo prop = obj.GetType().GetProperty(column.ColumnName);
if (prop != null)
{
str = column.ColumnName;
try
{
objDictionary.Add(str, row[str].ToString());
object value = row[column.ColumnName];
Type vType = obj.GetType();
if (value == DBNull.Value)
{
if (vType == typeof(int) || vType == typeof(Int16)
|| vType == typeof(Int32)
|| vType == typeof(Int64)
|| vType == typeof(decimal)
|| vType == typeof(float)
|| vType == typeof(double))
{
value = 0;
}
else if (vType == typeof(bool))
{
value = false;
}
else if (vType == typeof(DateTime))
{
value = DateTime.MaxValue;
}
else
{
value = null;
}
prop.SetValue(obj, value, null);
}
else
{
prop.SetValue(obj, value, null);
}
}
catch(Exception ex)
{
}
}
}
PropertyInfo ActionProp = obj.GetType().GetProperty("ActionTemplateValue");
if (ActionProp != null)
{
object ActionValue = objDictionary;
ActionProp.SetValue(obj, ActionValue, null);
}
}
return obj;
}
}

You can use a generic method like that for datatable to generic list
public static List<T> DataTableToList<T>(this DataTable table) where T : class, new()
{
try
{
List<T> list = new List<T>();
foreach (var row in table.AsEnumerable())
{
T obj = new T();
foreach (var prop in obj.GetType().GetProperties())
{
try
{
PropertyInfo propertyInfo = obj.GetType().GetProperty(prop.Name);
if (propertyInfo.PropertyType.IsEnum)
{
propertyInfo.SetValue(obj, Enum.Parse(propertyInfo.PropertyType, row[prop.Name].ToString()));
}
else
{
propertyInfo.SetValue(obj, Convert.ChangeType(row[prop.Name], propertyInfo.PropertyType), null);
}
}
catch
{
continue;
}
}
list.Add(obj);
}
return list;
}
catch
{
return null;
}
}

Converting DataTable to Generic Dictionary
public static Dictionary<object,IList<dynamic>> DataTable2Dictionary(DataTable dt)
{
Dictionary<object, IList<dynamic>> dict = new Dictionary<dynamic, IList<dynamic>>();
foreach(DataColumn column in dt.Columns)
{
IList<dynamic> ts = dt.AsEnumerable()
.Select(r => r.Field<dynamic>(column.ToString()))
.ToList();
dict.Add(column, ts);
}
return dict;
}

Use Extension :
public static class Extensions
{
#region Convert Datatable To List
public static IList<T> ToList<T>(this DataTable table) where T : new()
{
IList<PropertyInfo> properties = typeof(T).GetProperties().ToList();
IList<T> result = new List<T>();
foreach (var row in table.Rows)
{
var item = CreateItemFromRow<T>((DataRow)row, properties);
result.Add(item);
}
return result;
}
private static T CreateItemFromRow<T>(DataRow row, IList<PropertyInfo> properties) where T : new()
{
T item = new T();
foreach (var property in properties)
{
property.SetValue(item, row[property.Name], null);
}
return item;
}
#endregion
}

To assign the DataTable rows to the generic List of class
List<Candidate> temp = new List<Candidate>();//List that holds the Candidate Class,
//Note:The Candidate class contains RollNo,Name and Department
//tb is DataTable
temp = (from DataRow dr in tb.Rows
select new Candidate()
{
RollNO = Convert.ToInt32(dr["RollNO"]),
Name = dr["Name"].ToString(),
Department = dr["Department"].ToString(),
}).ToList();

you can use following two Generic functions
private static List<T> ConvertDataTable<T>(DataTable dt)
{
List<T> data = new List<T>();
foreach (DataRow row in dt.Rows)
{
T item = GetItem<T>(row);
data.Add(item);
}
return data;
}
private static T GetItem<T>(DataRow dr)
{
Type temp = typeof(T);
T obj = Activator.CreateInstance<T>();
foreach (DataColumn column in dr.Table.Columns)
{
foreach (PropertyInfo pro in temp.GetProperties())
{
if (pro.Name == column.ColumnName)
pro.SetValue(obj, dr[column.ColumnName].ToString(), null);
else
continue;
}
}
return obj;
}
and use it as following
List<StudentScanExamsDTO> studentDetails = ConvertDataTable<StudentScanExamsDTO>(dt);

If anyone want's to create custom function to convert datatable to list
class Program
{
static void Main(string[] args)
{
DataTable table = GetDataTable();
var sw = new Stopwatch();
sw.Start();
LinqMethod(table);
sw.Stop();
Console.WriteLine("Elapsed time for Linq Method={0}", sw.ElapsedMilliseconds);
sw.Reset();
sw.Start();
ForEachMethod(table);
sw.Stop();
Console.WriteLine("Elapsed time for Foreach method={0}", sw.ElapsedMilliseconds);
Console.ReadKey();
}
private static DataTable GetDataTable()
{
var table = new DataTable();
table.Columns.Add("ID", typeof(double));
table.Columns.Add("CategoryName", typeof(string));
table.Columns.Add("Active", typeof(double));
var rand = new Random();
for (int i = 0; i < 100000; i++)
{
table.Rows.Add(i, "name" + i, rand.Next(0, 2));
}
return table;
}
private static void LinqMethod(DataTable table)
{
var list = table.AsEnumerable()
.Skip(1)
.Select(dr =>
new Category
{
Id = Convert.ToInt32(dr.Field<double>("ID")),
CategoryName = dr.Field<string>("CategoryName"),
IsActive =
dr.Field<double>("Active") == 1 ? true : false
}).ToList();
}
private static void ForEachMethod(DataTable table)
{
var categoryList = new List<Category>(table.Rows.Count);
foreach (DataRow row in table.Rows)
{
var values = row.ItemArray;
var category = new Category()
{
Id = Convert.ToInt32(values[0]),
CategoryName = Convert.ToString(values[1]),
IsActive = (double)values[2] == 1 ? true : false
};
categoryList.Add(category);
}
}
private class Category
{
public int Id { get; set; }
public string CategoryName { get; set; }
public bool IsActive { get; set; }
}
}
If we execute above code, Foreach method finishes in 56ms while linq one takes 101ms ( for 1000 records).
So Foreach method is better to use.
Source:Ways to Convert Datatable to List in C# (with performance test example)

try this using Newtonsoft Json:
var json = JsonConvert.SerializeObject(dataTable);
var YourConvertedDataType = JsonConvert.DeserializeObject<YourDataType>(json);

To get List of values instead of ItemArray, do this:
List<string> s = dt.AsEnumerable().Select(x => x[0].ToString()).ToList();
The above assumes that you want list of string values from column 0.