Some Useful Extension Methods On IList<T> zt
Some Useful Extension Methods On IList<T>
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INSTANTLY dtSearch TERABYTES OF POPULAR DATA TYPES; hundreds of reviews, etc.!
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Often I need to convert a List of a certain type to a CSV string, or to a DataTable. Here I provide four extension methods: 1) public static DataTable ToDataTable<T>(this IList<T> data) (List<T> to DataTable. 2) public static string ToCsv<T>(this IList<T> data) ( List<T> to CSV string. 3) public static string ToCsv(this DataTable dt) ( DataTable to CSV string. 4) public static void WriteDelimitedFile<T>(this IEnumerable<T> list, string logfile, string delimiter)
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Extension methods are great for utility purposes as there is no need to reference
the class in which they are defined, nor to instantiate any objects.
if you have a DataTable "dt" you can simply call dt.ToCsv() to get a CSV
delimited string. Likewise if you have a List<Person> "people"
you can call people.ToCsv(). I have also included a public static void WriteDelimitedFile<T>(this IEnumerable<T> list, string logfile, string delimiter) extension method.
Here is the code for the extension methods:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.IO;
using System.Linq;
using System.Text;
namespace ListExtensions
{
public static class ListExtensions
{
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;
}
public static string ToCsv<T>(this IList<T> data)
{
PropertyDescriptorCollection props =TypeDescriptor.GetProperties(typeof(T));
StringBuilder sb = new StringBuilder();
for (int i = 0; i < props.Count; i++)
{
PropertyDescriptor prop = props[i];
sb.Append( prop.Name);
if (i < props.Count - 1)
{
sb.Append(",");
}
}
sb.Append(Environment.NewLine);
var values = new object[props.Count];
foreach (T item in data)
{
for (int i = 0; i < values.Length; i++)
{
values[i] = props[i].GetValue(item);
sb.Append( values[i].ToString() );
if (i < values.Length - 1)
{
sb.Append(",");
}
}
sb.Append( Environment.NewLine);
}
return sb.ToString();
}
public static string ToCsv(this DataTable dt)
{
MemoryStream ms = new MemoryStream();
StreamWriter sw = new StreamWriter(ms);
int iColCount = dt.Columns.Count;
for (int i = 0; i < iColCount; i++)
{
sw.Write(dt.Columns[i]);
if (i < iColCount - 1)
{
sw.Write(",");
}
}
sw.Write(sw.NewLine);
foreach (DataRow dr in dt.Rows)
{
for (int i = 0; i < iColCount; i++)
{
if (!Convert.IsDBNull(dr[i]))
{
sw.Write(dr[i].ToString());
}
if (i < iColCount - 1)
{
sw.Write(",");
}
}
sw.Write(sw.NewLine);
}
sw.Close();
return System.Text.Encoding.UTF8.GetString(ms.ToArray());
}
public static void WriteDelimitedFile<T>(this IEnumerable<T> list, string logfile, string delimiter)
{
using (var sw = File.AppendText(logfile))
{
var props = typeof(T).GetProperties();
var headerNames = props.Select(x => x.Name);
sw.WriteLine(string.Join(delimiter, headerNames.ToArray()));
foreach (var item in list)
{
var item1 = item;
var values = props
.Select(x => x.GetValue(item1, null) ?? "")
.Select(x => x.ToString())
.Select(x => x.Contains(delimiter) || x.Contains("\n") ? "\"" + x + "\"" : x);
sw.WriteLine(string.Join(delimiter, values.ToArray()));
}
sw.Close();
}
}
}
}
And here is a short Console Application to exercise the above:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Linq;
using System.Text;
using ListExtensions;
namespace ConsoleApplication1
{
public class Test
{
public String Name { get; set; }
public String Address { get; set; }
public string City { get; set; }
public string State { get; set; }
public string Zipcode { get; set; }
}
class Program
{
static void Main(string[] args)
{
List<Test> tests = new List<Test>();
for (int i = 0; i < 3; i++)
{
Test t = new Test()
{
Name = "Peter Bromberg",
Address = "123 High St #10" + i,
City = "Pocahontas",
State = "FL",
Zipcode = "32323"
};
tests.Add(t);
}
DataTable dt = tests.ToDataTable();
string csv2 = dt.ToCsv();
string csv = tests.ToCsv();
Console.WriteLine(csv);
Console.WriteLine("===========================================================");
Console.WriteLine(csv2);
tests.WriteDelimitedFile(@"C:\temp\log.csv",",");
Console.WriteLine("Any key to quit.");
Console.ReadKey();
}
}
}
You can download the Visual Studio 2010 solution here.
