How to Export DataTable into Excel - c#-4.0

Question

I have list of objects and i converted those into data table now i am unable to export those into excel
Below is the sample code
class Program
{
static void Main(string[] args)
{
Student s1 = new Student("Student-A",100);
Student s2 = new Student("Student-B", 90);
Student s3 = new Student("Student-C", 80);
List<Student> studentList = new List<Student>() { s1,s2,s3};
ListToDataTable converter = new ListToDataTable();
DataTable dt = converter.ToDataTable(studentList);
Console.WriteLine();
}
}
Below is the student class which has two properties
class Student
{
public string Name { get; set; }
public int? Score { get; set; }
public Student(string name,int? score)
{
this.Name = name;
this.Score = score;
}
}
Below is the class used for converting list of objects to data table
public class ListToDataTable
{
public DataTable ToDataTable<T>(List<T> items)
{
DataTable dataTable = new DataTable(typeof(T).Name);
PropertyInfo[] Props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (PropertyInfo prop in Props)
{
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;
}
}

Answer 1

Try to create a simple CSV file from your DataTable.

Answer 2

You can use the following DataTable extension, after you have converted your list to a DataTable.
public static string ToCSV(this DataTable table)
{
var result = new StringBuilder();
for (int i = 0; i < table.Columns.Count; i++)
{
result.Append(table.Columns[i].ColumnName);
result.Append(i == table.Columns.Count - 1 ? "\n" : ",");
}
foreach (DataRow row in table.Rows)
{
for (int i = 0; i < table.Columns.Count; i++)
{
result.Append(row[i].ToString());
result.Append(i == table.Columns.Count - 1 ? "\n" : ",");
}
}
return result.ToString();
}
Example of usage :
// replace with your data table here
DataTable dt = new DataTable();
var bytes = Encoding.GetEncoding("iso-8859-1").GetBytes(dt.ToCSV());
MemoryStream stream = new MemoryStream(bytes);
StreamReader reader = new StreamReader(stream);
Response.Clear();
Response.Buffer = true;
Response.AddHeader("content-disposition", string.Format("attachment;filename={0}.csv", "filename"));
Response.ContentType = "application/text";
Response.ContentEncoding = Encoding.Unicode;
Response.Output.Write(reader.ReadToEnd());
Response.Flush();
Response.End();

Answer 3

Since you have this tagged as interop, I went that route (no need to create a csv file, just export directly to excel).
This solution is not the prettiest, but it works. I've also changed it some as you can export your studentList directly to excel (no need to convert it to a dataTable first).
First thing, in your solution, you need to add a reference to "Microsoft.Office.Interop.Excel". To do this, right click on "References" in Solution Explorer, then "Add Reference", then click on the ".NET" tab, then scroll down to find it.
Once that is done, update your code as follows:
using System;
using System.Collections.Generic;
using Excel = Microsoft.Office.Interop.Excel;
static void Main()
{
var s1 = new Student("Student-A", 100);
var s2 = new Student("Student-B", 90);
var s3 = new Student("Student-C", 80);
var studentList = new List<Student> { s1, s2, s3 };
// Create an excel sheet
var xlApp = new Excel.Application { Visible = true }; // Create instance of Excel and make it visible.
xlApp.Workbooks.Add(Excel.XlSheetType.xlWorksheet); // Create a workbook (WB)
var xlWS = (Excel.Worksheet)xlApp.ActiveSheet; // Reference the active worksheet (WS)
xlWS.Name = "Exported Student"; // Name the worksheet
// Add Header fields to Excel [row, column]
var r = 1;
xlWS.Cells[r, 1] = "Name";
xlWS.Cells[r, 2] = "Score";
// Copy data from StudentList to Excel
foreach (Student student in studentList)
{
r++;
xlWS.Cells[r, 1] = student.Name;
xlWS.Cells[r, 2] = student.Score;
}
}
This will automatically export your studentList to an excel sheet. There wasn't a need for the ListToDataTable class.