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A free "Export to Excel" C# class, using OpenXML

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17 Dec 2013CPOL4 min read 506.5K   19.3K   182   140
How to easily add an "export to Excel" feature to your app

Introduction

It's amazing that even now, in 2013, there are so many developers still asking for help on how to write C# and VB.NET code to export their data to Excel.

Even worse, a lot of them will stumble on articles suggesting that they should write their data to a comma-separated file, but to give the file a .xls extension.

So today, I'm going to walkthrough how to use my C# "Export to Excel" class which you can add to your C# WinForms / WPF / ASP.NET application, using one line of code.

Depending on whether your data is stored in a DataSet, DataTable, or List<>, you simply need to call one of these three functions, and tell them what (Excel) file name you want to write to.

C#
public static bool CreateExcelDocument<T>(List<T> list, string ExcelFilename
public static bool CreateExcelDocument(DataTable dt, string ExcelFilename
public static bool CreateExcelDocument(DataSet ds, string ExcelFilename)

Here's a simple example.

We create a DataSet, fill it with some data (just add your own CreateSampleData function), then call the CreateExcelFile.CreateExcelDocument function, passing it the DataSet and a filename:

C#
// Step 1: Create a DataSet, and put some sample data in it
DataSet ds = CreateSampleData();

// Step 2: Create the Excel .xlsx file
try
{
    CreateExcelFile.CreateExcelDocument(ds, "C:\\Sample.xlsx");
}
catch (Exception ex)
{ 
    MessageBox.Show("Couldn't create Excel file.\r\nException: " + ex.Message);
    return;
}   

And that's all you have to do. The CreateExcelDocument function will create a "real" Excel file for you.

For example, if you had a created a DataSet containing three DataTables called:

  • Drivers
  • Vehicles,
  • Vehicle Owners,

..then here's what your Excel file would look like. The class would create one worksheet per DataTable, and each worksheet would contain the data from that DataTable.

Sample spreadsheet

The full source code for this C# class is freely downloadable here (click on the "Browse code" link in the left-hand panel), or you can download this full demo, plus a VB.NET version of the class, from my blog, MikesKnowledgeBase.

Adding the library to your application

The C# code above shows how easy it is to call the CreateExcelFile class.

C#
DataSet ds = CreateSampleData();
CreateExcelFile.CreateExcelDocument(ds, "C:\\Sample.xlsx");

However, to use this library, you'll need to add two files from the free Microsoft OpenXML SDK:

  • DocumentFormat.OpenXml.dll: From the free Microsoft Open XML SDK library
  • WindowsBase.dll: From the Microsoft .NET Framework library

Add these two DLLs to your project's References section, and remember to set them to "Copy Local".

Copy Local

Then, just download the CreateExcelFile.cs file (via the "Browse code" link in CodeProject's left-hand panel), and add it to your application. 

And that's it.

Regardless of if your data is stored in a List<>, DataTable, or DataSet, you can export it to a "real" Office 2007 Excel .xlsx file using that one line of code.

And because it is created using the OpenXML library, you can run this code on machines which don't have Excel installed.

ASP.NET

For ASP.NET developers, I've added three extra functions.

C#
public static bool CreateExcelDocument<T>(List<T> list, string filename, System.Web.HttpResponse Response)
public static bool CreateExcelDocument(DataTable dt, string filename, System.Web.HttpResponse Response)
public static bool CreateExcelDocument(DataSet ds, string filename, System.Web.HttpResponse Response)

Rather than creating the Excel file in a temporary directory, then having to load in the file and output it to the webpage's HttpResponse, you can get the library to write directly to the HttpResponse.

However, by default, this functionality is disabled (to prevent build issues for the non ASP.NET developers). To enable these three functions, you need to make two changes.

First, uncomment the top line of the CreateExcelFile.cs code, so that it now reads:

C#
#define INCLUDE_WEB_FUNCTIONS   

Now, you need to add a Reference to the System.Web .NET library:

Adding a reference

Once you've done these two steps, the CreateExcelFile library is ready to go.

For example, in this example, my ASP.NET C# code has a list of Employee records, stored in a List<Employeee>. I add an "Export to Excel" button to my webpage, and when the user clicks on it, I just need one simple call to the CreateExcelFile class.

C#
// In this example, I have a defined a List of my Employee objects.<br />class Employee;
List<Employee> listOfEmployees = new List<Employee>();
...
 
// The following ASP.Net code gets run when I click on my "Export to Excel" button.
protected void btnExportToExcel_Click(object sender, EventArgs e)
{
    // It doesn't get much easier than this...
    CreateExcelFile.CreateExcelDocument(listOfEmployees, "Employees.xlsx", Response);
}

And that's it. A real Excel file, in one line of code.

Going forward

You'll notice that this library is excellent for one job - writing plain, boring data to an Excel file. I haven't attempted to add any classes to add formatting, colors, pivot tables or anything else.

However, this class is an excellent way to get started (without paying for third-party software to create the Excel file for you), and if you want to take this further, you'll soon find that Googling will easily find you extra source code to add on top of this.

For example, if you wanted to add a background color to some of the cells in the Excel file, simply Google "open XML background color" and you'll have many articles showing you how to do this.

The reason I wrote this article is that I found that it was very hard to find a free, easy to use C# library which actually created the OpenXML Excel file in the first place.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Software Developer
Switzerland Switzerland
Full-stack Software Developer, working for an insurance company in Zurich, Switzerland.

More developer tips'n'trip at my website:
http://www.MikesKnowledgeBase.com

Comments and Discussions

 
QuestionThank you! Thank You! Pin
sonnytle11-Dec-15 4:54
sonnytle11-Dec-15 4:54 
PraiseHi Pin
Javed Akhtar22-Oct-15 23:02
Javed Akhtar22-Oct-15 23:02 
QuestionListToDataTable is converting Enum value to int. Pin
ajay kotnala17-Sep-15 21:09
ajay kotnala17-Sep-15 21:09 
GeneralJust Awesome was looking for open sources but nothing worked Pin
reddyreddy720-Aug-15 7:53
reddyreddy720-Aug-15 7:53 
GeneralRe: Just Awesome was looking for open sources but nothing worked Pin
Michael Gledhill21-Aug-15 2:57
Michael Gledhill21-Aug-15 2:57 
QuestionThis is not support very large file (30MB) in asp.net Pin
Member 328855220-Jun-15 16:09
Member 328855220-Jun-15 16:09 
AnswerRe: This is not support very large file (30MB) in asp.net Pin
Michael Gledhill6-Oct-15 1:15
Michael Gledhill6-Oct-15 1:15 
GeneralMy vote of 5 Pin
tklempay3-Jun-15 7:40
tklempay3-Jun-15 7:40 
QuestionFix Column Width as per highest string data into the cell Pin
Sopan Maiti2-Jun-15 3:42
Sopan Maiti2-Jun-15 3:42 
GeneralCodeProject issue Pin
Michael Gledhill1-Jun-15 21:17
Michael Gledhill1-Jun-15 21:17 
GeneralRe: CodeProject issue Pin
Member 115248382-Aug-15 9:50
Member 115248382-Aug-15 9:50 
GeneralRe: CodeProject issue Pin
reddyreddy720-Aug-15 8:02
reddyreddy720-Aug-15 8:02 
Questioninsert into Pin
Member 871442125-May-15 9:10
Member 871442125-May-15 9:10 
QuestionAwesome Pin
OmidGer6-May-15 4:26
OmidGer6-May-15 4:26 
AnswerRe: Awesome Pin
Michael Gledhill7-May-15 21:07
Michael Gledhill7-May-15 21:07 
QuestionHow to format a column as Date? Pin
Jaime Stuardo - Chile2-May-15 7:30
Jaime Stuardo - Chile2-May-15 7:30 
AnswerRe: How to format a column as Date? Pin
Michael Gledhill7-May-15 22:49
Michael Gledhill7-May-15 22:49 
QuestionLanguage dependent column names Pin
Mårten Sörliden8-Apr-15 2:40
professionalMårten Sörliden8-Apr-15 2:40 
QuestionAddHeader needs filename='" + filename + "'" to work in Google Chrome Pin
Mårten Sörliden7-Apr-15 5:13
professionalMårten Sörliden7-Apr-15 5:13 
QuestionWhat about this DLL? Pin
dietmar paul schoder28-Feb-15 3:43
professionaldietmar paul schoder28-Feb-15 3:43 
AnswerRe: What about this DLL? Pin
Michael Gledhill18-Mar-15 1:30
Michael Gledhill18-Mar-15 1:30 
GeneralRe: What about this DLL? Pin
dietmar schoder18-Mar-15 1:43
dietmar schoder18-Mar-15 1:43 
QuestionIn Webmatrix I can't get it to work Pin
MarcelloCarrabba10-Feb-15 5:24
professionalMarcelloCarrabba10-Feb-15 5:24 
Questionxls extension error Pin
Member 1106205626-Jan-15 4:51
Member 1106205626-Jan-15 4:51 
AnswerRe: xls extension error Pin
Mike Gledhill29-Jan-15 22:23
Mike Gledhill29-Jan-15 22:23 

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