The scenario:
I was using the AJAX AutoCompleteExtender when I realized that inside the ServiceMethod of my AutoCompleteExtender, I needed to call a method that needed between it’s parameters an Enum.

To the ServiceMethod of an AutoCompleteExtender, you can pass parameters through the contextKey. Nonetheless I couldn’t pass an enum, so I decided to pass the name of the Database as an string, and then inside the ServiceMethod convert the string into an enum.

Anyways, this is how you convert a string into an enum:

private void Form1_Load(object sender, EventArgs e)
{
DataBase db = convertStringToEnum("Pubs");
MessageBox.Show(db.ToString());
}
private DataBase convertStringToEnum(string dbName)
{
return (DataBase)Enum.Parse(typeof(DataBase), dbName);
}
public enum DataBase
{
Northwind = 0,
Pubs = 1
}


If you have any questions, feel free to leave a comment.

In my previous post, I had a WPF ListView that displayed two items, and each item occupied one row and one column.

But what if I would like to add an item to a WPF ListView but this time that one row contains more than one column. In this way we can answer questions such as: “How to add a ListView item in two columns using c# code”. If this is the question you are looking to answer, you have found just what you were looking for. I will show you how to do the following in Visual Studio 2008:

Window1.xaml

<Window x:Class=”ListViewProj.Window1″
xmlns=”http://schemas.microsoft.com/winfx/2006/xaml/presentation”
xmlns:x=”http://schemas.microsoft.com/winfx/2006/xaml”
Title=”Window1″ Height=”220″ Width=”285″>
<Grid>
<ListView Margin=”11,16,35,17″ Name=”listView1″ />
</Grid>
</Window>

Window1.xaml.cs

public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
// The constructor accepts a first name, last name, major
Student student = new Student("Daniel","Isaacs","Computer Science");
ObservableCollection <studentObj> = new ObservableCollection();
// add a student
studentObj.Add(student);
// displays data items in columns for a ListView
GridView gView = new GridView();
// set the first gridview column
GridViewColumn firstCol = new GridViewColumn();
// set the data item to bind to for this column
firstCol.DisplayMemberBinding = new Binding(”FirstName”);
firstCol.Header = “First Name”;
// set the second gridview column
GridViewColumn secondCol = new GridViewColumn();
secondCol.DisplayMemberBinding = new Binding(”LastName”);
secondCol.Header = “Last Name”;
// set the third gridview column
GridViewColumn thirdCol = new GridViewColumn();
thirdCol.DisplayMemberBinding = new Binding(”Major”);
thirdCol.Header = “Major”;
// add gridview columns
gView.Columns.Add(firstCol);
gView.Columns.Add(secondCol);
gView.Columns.Add(thirdCol);
// set the collection that is going to be used to generate content
listView1.ItemsSource = studentObj;
// sets how data is organized and styled
listView1.View = gView;
}
}


In the XAML code I only added a ListView. In the code behind I created an instance of the Student class (a class I created for this example). Then I add the instance of the student class to the collection that is going to be used to generate content.

I also created an instance of the GridView class, because the gridview is how we are going to organized the data. After this I create three instances of the GridViewColumn class(you can created as many instances of the GridViewColumn as you need). Each GridViewColumn needs a binding (DisplayMemberBinding) which sets the data item to bind to for this column.

Don’t forget to add the GridViewColumn to the GridView. At the end assign to the listView ItemSource Property the collection with the content, and assign to the listview View Property the Gridview instance.

Here’s a copy of my files.

If you have any comments or questions just let me know.

To do this I decided to use the ASP.NET AJAX TOOLKIT. I am using Visual Web Developer 2008 Express to do this, I created a new website, and started working from here.

To accomplish this you will need to:

1- Add the AjaxControlToolkit.dll to your project(Add reference -> Browse tab ). When you download the tookit you can search for this dll, and you should be able to find it.
(I found mine in this path: Visual Studio 2005\Templates\ProjectTemplates\Visual C#\AjaxControlExtenderProjectCS\AjaxControlToolkit.dll)
2- Add a webform to your project
3- Add a web service to your project
4- Add a style sheet to your project

The Webform:
I will proceed to explain several parts of the webform

Before the HTML you need to register the Ajax Control Toolkit custom control.
<%@ Register
Assembly=”AjaxControlToolkit”
Namespace=”AjaxControlToolkit”
TagPrefix=”ajaxToolkit” %>

Don’t forget to add the style sheet we are using.
<link href=”StyleSheet.css” rel=”stylesheet” type=”text/css” />

Inside the form I have the following:
First, I start adding a toolkit script manager:
<ajaxtoolkit:toolkitscriptmanager runat=”server” id=”ScriptManager1″/>
If you don’t do this you might get an error that says “The control with ID ‘AutoComplete1′ requires a ScriptManager on the page. The ScriptManager must appear before any controls that need it.”. The reason you need it (as I understand it) is that the toolkit script manager merges multiple javascript scripts into one file, which is downloaded at runtime.

Then, you need a textbox, which is where your search is going to be typed.
<asp:textbox runat=”server” id=”txtInput” width=”300″/>

Of course, you need to add in the form the ASP.NET AJAX AutoComplete Extender. According to the asp.net webpage this extender:”can be attached to any TextBox control, and will associate that control with a popup panel to display words that begin with the prefix typed into the textbox.”. This is how the extender looks in my form:
<ajaxToolkit:AutoCompleteExtender
runat=”server”
ID=”AutoComplete1″
TargetControlID =”txtInput”
ServiceMethod=”GetCustomersContactTitle”
ServicePath=”WebService.asmx”
MinimumPrefixLength=”2″
CompletionInterval=”1000″
EnableCaching=”true”
CompletionSetCount=”20″
CompletionListCssClass=”flyout-background”
CompletionListItemCssClass=”flyout-item”
CompletionListHighlightedItemCssClass=”flyout-item-hover”>
</ajaxToolkit:AutoCompleteExtender>

This is what the webform needs, nonetheless, this is very basic, because my purpose is to show how this works, and that you can also understand what everything means.

Now, I am going to write about the two most important parts of the webservice :

First, make sure this line is commented when you add your Webservice. This line needs to be uncommented, since you need to call the webservice from your webform.
// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
[System.Web.Script.Services.ScriptService]

Last but not least, you need a method that returns the data to be displayed. My method basically gets the ContactTitle Column in the Customers table which is located in the Northwind database. I used this database since it is available to everyone. The AJAX AutoComplete Extender requires that the method that you use to display data, matches the following signature: a method that returns an array of strings, and has two parameters, which is the prefix the user just entered, and the amount of records to be displayed.


[WebMethod]
public string[] GetCustomersContactTitle(string prefixText, int count)
{
List<string> items = new List<string>(count);
DataSet ds = new DataSet();string connectionString = "Data Source=(local);Initial Catalog=Northwind;Integrated Security=SSPI;";
using(SqlConnection connection = new SqlConnection(connectionString))
{
string sql = "SELECT ContactTitle FROM Customers WHERE ContactTitle LIKE '" + prefixText + "%'";
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand = new SqlCommand(sql,connection);
adapter.Fill(ds);
}
foreach (DataRow dr in ds.Tables[0].Rows)
{
items.Add(dr["ContactTitle"].ToString());
}
return items.ToArray();
}


Finally, the stylesheet, to have a better understanding on the CSS Classes I would recommend that you play with them, so you have a better understanding on what they do. Nonetheless, I provided a description of what they do.

This class is going to be applied to the completion list flyout.
.flyout-background {
border: 1px solid #009;
list-style-type: none;
margin: 0px;
background-color: #FFFFFF;
text-align: left;
}

This class is going to be applied to an item in the AutoComplete list flyout.
.flyout-item {
color: #FF0000;
}

This class is going to be applied to a highlighted item in the AutoComplete list flyout.
.flyout-item-hover {
background-color: #66FFFF;
}

This is the final result:

Here’s a copy of my files

If you have any comments just let me know.

The device, \Device\Harddisk0, has a bad block.

I was able to fix this doing the following:

• Do a right click on your C: drive.
• Select properties
• Click on the Tools tab, in the Error-Checking section click the “Check Now” button.

• Select all the Check disc options and press start.

After I did all this I got the following message: “The disk check could not be performed because the disk check utility needs exclusive access to some Windows files on the disk. These files can be accessed only by restarting Windows. Do you want to schedule this disk check to occur the next time you restart the computer?” press “Yes” and the next time you restart your computer a CHKDSK (Checkdisk) is going to be performed. This fixed my problem.

If you have another way of fixing this problem, please let me know.

I am using ASP.NET to do this:

Default.aspx

<form id=”form1″ runat=”server”>
<asp:listbox id=”ListBox1″ runat=”server”></asp:listbox>
</form>

I just declare a listbox inside the form.

Default.aspx.cs

public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
foreach (string subDirectory in
System.IO.Directory.GetDirectories(
AppDomain.CurrentDomain.BaseDirectory))
{
// split the folders into an array of strings
string[] directory = subDirectory.Split(new char[] { '\\' });
// how many folders do we have?
int numOfDirectories = directory.Length;
// the last folder is the folder we are looking for
ListBox1.Items.Add(directory[numOfDirectories - 1]);
}
}
}


System.IO.Directory.GetDirectories as MSDN states: “Gets the names of subdirectories in the specified directory”. However, you get an absolute path of the directory.

If you would like to add the name of the folder to a listbox you will need to split the string that contains the different directories and store the directories in an array of strings:

string[] directory = subDirectory.Split(new char[] { ‘\\’ });

After this step, you get the amount of directories the absolute path has, and then look for the last directory in the array:

int numOfDirectories = directory.Length;
ListBox1.Items.Add(directory[numOfDirectories - 1]);

The directory I am using to read the files is AppDomain.CurrentDomain.BaseDirectory which is the base directory that the assembly resolver uses to search for assemblies.

The result of this snippet is:

I am using ASP.NET to do this:

Default.aspx

<form id=”form1″ runat=”server”>
<asp:listbox id=”ListBox1″ runat=”server”></asp:listbox>
</form>

I just declare a listbox inside the form.

Default.aspx.cs

public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
// the comma delimited list
string names = "Lesseps,Daniel,Isaacs,Diaz";
// split the string and make it an array of strings
string[] listOfNames = names.Split(new char[] { ',' });
// sort the array of strings
Array.Sort(listOfNames);
foreach (string name in listOfNames)
{
ListBox1.Items.Add(name);
}
}
}

The result:

In C#, it is extremely easy to sort an array of strings, just use:

Array.Sort(listOfNames);

where listOfNames is an array of strings.

“This product requires ASP.Net web service extensions to be enabled in Internet Information Services (IIS)”.

I went into my Administrative Tools-> Internet Information Services (IIS) Manager, and I didn’t find my Web Service Extension for ASP.NET 2.0. Consequently, I had to install asp.net (2.0.50727) WebService Extensions.

In order to do this, I used a command prompt and went to:

C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727.

In that directory I typed:

aspnet_regiis -i

After this you should see in your command prompt something that says like this: “Start installing ASP.NET (2.0.50727)”. After the extensions are installed you should see something like this: “Finished installing ASP.NET (2.0.50727)”. At this point, this error should be solved, and your ASP.NET 2.0 WebService Extensions should be installed.

LINQ according to the research I did in MSDN is a “set of extensions to the .NET Framework that encompass language-integrated query, set, and transform operations.” In MSDN they define LINQ in simple terms, and state that “LINQ is a series of language extensions that supports data querying in a type-safe way”. The last interesting fact I found in MSDN about LINQ is that “the data to be queried can take the form of XML, databases, objects, and so on”.

There’s a lot of theory about LINQ in MSDN and in the internet, but my purpose is to give you a quick start in how to start coding LINQ applications.

The first step is to download the “Language Interated Query, May 2006 Community Technology Preview”. The link to this preview is here.

The importance of installing this extension is that if you go to Visual Studio 05, and press File->New->Project , you will see in your Visual C# tree a node that says “LINQ Preview” which will give you the option to create a LINQ Console Application, LINQ Windows Application, LINQ Library, and LINQ WinFX Application.

For this introduction I’m going to choose a LINQ Windows Application. When a LINQ Windows Application is created you will be able to see DLL’s needed for LINQ applications such as: System.Data.DLinq, System.Data.Extensions, System.Query, System.Xml.XLinq.

Now that you have your LINQ Windows Application created, the task will be the following:
Display an array of strings ordered alphabetically in a listbox.

This is how you can do this:

private void Form1_Load(object sender, EventArgs e)
{
string[] names = { "Daniel", "Lesseps", "Isaacs", "Diaz" };
var namesToDisplay = from name in names
orderby name
select name;
foreach(var name in namesToDisplay)
listBox1.Items.Add(name);
}

When our form loads the first line declares an array of strings that contains 4 words.

The next line is a sample LINQ query, and I will explain this line as I understand it (which means that if you have any input on my explanation it will be appreciated) . As you can see LINQ queries start with “var” which indicates it’s a local variable. The LINQ query contains clauses like: FROM, WHERE, SELECT,ORDERBY, GROUP BY, and others. This example starts with “from name in names”. The part “in names” is very important since it’s specifying the list that is going to be queried. After this I’m ordering the names alphabetically using “orderby name”. The last line of the query is the “select name(you can think of name as the name of my column)”. SQL queries start with the SELECT clause; however, LINQ queries end with the SELECT clause.

var namesToDisplay = from name in names
orderby name
select name;

After this we iterate the results of the query using a foreach, and each statement returns a name.

As you can see, SQL queries can now be integrated in C#.
Very interesting! This is a basic example,I will write more complex examples later on.

For some reason when I press a button and the button puts an error text in my cell (because of an error validation) when I go back to the cell, it selects all the text in the datagridviewcell and if you press a number you are going to be able to watch two behaviors:

1- The Datagridviewcell adds itself:
This was happening in my real world application.
For example, if I have a number like 1111.000 (let’s say this sends a validation error), if you go back to the cell and press “1″ you will see something like
1111.001
If you press “5″ you will see something like
1111.002
If you keep pressing numbers you will see that you will be adding your current number.

2- The Datagridviewcell will only let you put one number at a time.
This is what happens in the code below. If you press 1111.000 and you go back to the cell and press “1″ you will see something like
1.000

If you press “2″ instead of being 12.000 or 1.002 you will see
2.000

It will only let you put one number at a time.

Here’s the code for this scenario


using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Text.RegularExpressions;
namespace DataGridViewBugBlog
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
InitializeGridColumns();
FormatDataGridColumn(dataGridView1, "Price", typeof(double), null);
}
private void InitializeGridColumns()
{
DataSet ds = new DataSet();
DataTable dt = new DataTable();
ds.Tables.AddRange(new System.Data.DataTable[] {dt});
// Adding columns to the DataTable
dt.Columns.Add("Quantity", typeof(double));
dt.Columns.Add("Price", typeof(double));
dataGridView1.DataSource = ds.Tables[0].DefaultView;
// Setting the width of both columns
foreach (DataGridViewColumn col in dataGridView1.Columns)
col.Width = 95;
}
private void button1_Click(object sender, EventArgs e)
{
showConfirmation();
}
///

This only an excerpt of my code. The interesting part about this, is that what causes this error is the CurrentCellDirtyStateChanged event. I had this event because inside of it i had a CommitEdit method that raises the CellValueChanged event in which I was changing the values of some DataGridViewCheckBoxCell.

The solution:
Make sure in the CurrentCellDirtyStateChanged the CommitEdit is only made when you are in a DataGridViewCheckBoxCell. For the code above just comment the CommitEdit method and it will work like it should.