Create a CSV File from a .NET Generic List

Hi,

I've changed your code a little bit, 'cause it had some problems when using List.
Good luck,

Matthijs

///
/// Creates the CSV from a generic list.
/// ;
/// ;
/// The list.;
/// Name of CSV (w/ path) w/ file ext.;
public static void CreateCSVFromGenericList(this List list, string csvNameWithExt)
{
//todo: check for values that start with 0
if (list == null || list.Count == 0) return;

//get type from 0th member
var firstResult = (from a in list select a).FirstOrDefault();
Type t = firstResult.GetType();

string newLine = Environment.NewLine;

using (var sw = new StreamWriter(csvNameWithExt))
{
//Get first result of the type to figure out its props
if (firstResult != null)
{

//gets all properties
PropertyInfo[] props = firstResult.GetType().GetProperties();

//foreach of the properties in class above, write out properties
//this is the header row
foreach (PropertyInfo pi in props)
{
sw.Write(pi.Name.ToUpper() + ",");
}
sw.Write(newLine);

//this acts as datarow
foreach (T item in list)
{
//this acts as datacolumn
foreach (PropertyInfo pi in props)
{
//this is the row+col intersection (the value)
string whatToWrite =
Convert.ToString(item.GetType()
.GetProperty(pi.Name)
.GetValue(item, null))
.Replace(',', ' ') + ',';

sw.Write(whatToWrite);

}
sw.Write(newLine);
}
}
}
}

Thanks Kevin, I like your implementation. I made a small change to check for "\n" (newlines) as well. Below is the modified version:

///
/// Method to write a delimited file, given a generic enumerable.
///
/// The type T
/// an enumerable of type T
/// The destination file info
/// The delimiter ("," for example)
public static void WriteDelimitedFile(IEnumerable list, FileInfo saveFile, string delimiter)
{
if (list == null) return;
using (StreamWriter sw = saveFile.CreateText())
{
PropertyInfo[] props = typeof(T).GetProperties();
var headerNames = props.Select(x => x.Name);
sw.WriteLine(string.Join(delimiter, headerNames.ToArray()));
foreach (T item in list)
{
T item1 = item; // to prevent access to modified closure
var values = props
.Select(x => x.GetValue(item1, null) ?? "") // the null coalescing operator, replace null with ""
.Select(x => x.ToString())
.Select(x => x.Contains(delimiter) || x.Contains("\n") ? "\"" + x + "\"" : x); // if a value contains the delimiter, surround with quotes
sw.WriteLine(string.Join(delimiter, values.ToArray()));
}
sw.Close();
}
}

Here is an extension method I made based on your code.

-------------------------------

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Globalization;
using System.IO;
using System.Reflection;

public static class Extension
{
public static string BuildCsvString(this List myList)
{
if (myList != null && myList.Count > 0)
{
//Csv string
StringWriter mySw = new StringWriter();

//Add headers by looping properties of type
PropertyInfo[] properties = myList[0].GetType().GetProperties();
foreach (PropertyInfo curProp in properties)
{
mySw.Write('"' + curProp.Name.ToUpper() + '"' + ",");
}
mySw.Write('\n');

//Loop items in list (rows)
object curValue;
foreach (T curItem in myList)
{
//Loop properties (columns)
foreach (PropertyInfo curProp in properties)
{
//Get value, check, and write
curValue = curItem.GetType().GetProperty(curProp.Name).GetValue(curItem, null);
if(curValue != null)
{
mySw.Write('"' + curValue.ToString() + '"' + ",");
}
else
{
mySw.Write('"' + "" + '"' + ",");
}

}
mySw.Write('\n');
}

//Clean up and return
mySw.Close();
return mySw.ToString();
}
else
{
return "";
}
}
}

Hello,

Thanks for this code, I have modified it slightly and made it into an extender for any enumerable object:

public static string ToCSV(this IEnumerable collection)
{
if (collection == null || collection.Count() == 0) return string.Empty;

//get type from 0th member

string newLine = Environment.NewLine;

var sw = new StringBuilder();

//gets all properties
PropertyInfo[] props = typeof(T).GetProperties();

//foreach of the properties in class above, write out properties
//this is the header row
foreach (PropertyInfo pi in props)
{
sw.Append(pi.Name.ToUpper() + ",");
}
sw.Append(newLine);

//this acts as datarow
foreach (var item in collection)
{
//this acts as datacolumn
foreach (PropertyInfo pi in props)
{
//this is the row+col intersection (the value)
string whatToWrite =
Convert.ToString(item.GetType()
.GetProperty(pi.Name)
.GetValue(item, null))
.Replace(',', ' ') + ',';

sw.Append(whatToWrite);

}
sw.Append(newLine);
}
return sw.ToString();

}

So you can just call your collection.ToCSV() and it will return a CSV string that you can then output to file.

thanks, came in useful. needed a quickie way to save a list and this did it.

I know this is a c sharp site but...

Public Shared Sub WriteDelimitedFile(ByVal list As IEnumerable, ByVal saveFile As FileInfo, ByVal delimiter As String)
If list Is Nothing Then Return

OutputFile.Close()
End Using
End Sub

very good point [and nice article]. thanks!

I don't recommend this approach because it modifies values that contain embedded commas. You can leave such values intact by simply wrapping them with quotes.

I've published a couple of classes to read and write CSV files on Black Belt Coder. Perhaps some of your readers would be interested in seeing my version.

Thanks for this method, I started with this and made some changes to use LINQ syntax to avoid the for loops. Here is my implementation (sorry for no formatting)

///
/// Method to write a delimited file, given a generic enumerable.
///
/// The type T
/// an enumerable of type T
/// The destination file info
/// The delimiter ("," for example)
public static void WriteDelimitedFile(IEnumerable list, FileInfo saveFile,string delimiter)
{
if (list == null) return;
using (StreamWriter sw = saveFile.CreateText())
{
PropertyInfo[] props = typeof(T).GetProperties();
var headerNames = props.Select(x => x.Name);
sw.WriteLine(string.Join(delimiter, headerNames.ToArray()));
foreach (T item in list)
{
T item1 = item; // to prevent access to modified closure
var values = props
.Select(x => x.GetValue(item1, null) ?? "") // the null coalescing operator, replace null with ""
.Select(x => x.ToString())
.Select(x => x.Contains(delimiter) ? "\"" + x + "\"" : x); // if a value contains the delimiter, surround with quotes
sw.WriteLine(string.Join(delimiter, values.ToArray()));
}
sw.Close();
}
}

This is really nice to have in my bag of tricks now! Thanks for sharing! It's the kind of thing you never know when you'll need it, but saves the day when it does.

thanks!

Replace: 'Type t = list[0].GetType();' with typeof(T);