Nannette Thacker ShiningStar.net : ASP.NET

Nested Repeater AddHandler ItemCommand Not Firing

nannette — Fri, 30 Oct 2009 21:23:00 GMT

For those of you who program mostly in code behind, like I do, I have a gotcha for a nested repeater addhandler. The nested repeater is defined in the code in front: < asp : Repeater ID ="repTestKeyControl" runat ="server"> Your nested repeater...(read more)

Programmatic Menus: Optimize Your Menus in Code-behind

nannette — Wed, 03 Jun 2009 22:10:00 GMT

In this article, I want to show how you can setup your menus in code-behind and avoid redundancy. I recently inherited a web application with the menu system setup in the code-in-front. Each menu shared identical values, other than the visibility. Notice...(read more)

Storing and Retrieving Objects from View State - The Serializable Attribute

nannette — Tue, 10 Mar 2009 12:22:00 GMT

View State allows you to retain page property values, such as string and numeric types, between postbacks. You may also store class objects in View State, but you must first add the Serializable attribute. If you do not add the Serializable attribute...(read more)

Filtering Parameters in a SQL 2008 Stored Procedure

nannette — Thu, 05 Mar 2009 16:09:00 GMT

Ash explains the concept of Filtering Parameters in a Stored Procedure in this blog post. This method is safer and more beneficial than dynamically creating and passing a sql query from the code layer and using sp_executesql, as it helps to avoid sql...(read more)

Kudos to Telerik Support!

nannette — Fri, 27 Feb 2009 17:33:00 GMT

I have been using Telerik controls for about a year now. First, on a client site project, and then I licensed it for my own development needs as a consultant. I have to say I am tickled with the Telerik support. 1) Telerik forums are great. Ask a question...(read more)

VB.NET to C# Conversion Hints, Tips and Gotchas

nannette — Wed, 11 Feb 2009 16:36:00 GMT

If you're a VB.NET developer learning C# or converting your VB code to C#, here are a few hints, tips and gotchas. But first, let me share a few important links with you: VB.NET and C# Comparison - This is one of the most accurate and complete charts...(read more)

SQL Server 2008 Web Edition and Express Edition Errors Resolved

nannette — Sun, 01 Feb 2009 20:03:00 GMT

Since I had purchased the SQL Server 2008 Web Edition for my database server, I decided to also install it on my development box. But when I tried to install the Management Tools, it errored with: "Previous release of Microsoft Visual Studio 2008." I...(read more)

ASP.NET Web Application Development Consulting

nannette — Tue, 27 Jan 2009 16:20:00 GMT

Perhaps there are times when you just need a short-term ASP.NET developer for a 3-6 month project and don't wish to invest in a full-time employee. I am available for 1099 or W-2 consulting. No contract is required. Check out the details and my current...(read more)

Image Text using GDI+: Creating an Image from Text or Adding Text to an Existing Image

nannette — Wed, 14 Jan 2009 14:33:00 GMT

There are some nice tutorials on how to display text as an image. Some examples of when you might wish to use something like this is perhaps if you wish to display your email address on a web page, but don't want it to be harvested by spammers; a CAPTCHA for authenticating a real person on log in, or adding a URL to existing images on your site to keep them from being "swiped" by others.

I'm going to demonstrate the last scenario, a simple method that will print text to the bottom left of an image. You could easily alter it to pass in the x and y coordinates of where you wish to add the text, if desired.

Please download the ImageEdit.zip which contains code for both this example and an example of Resizing ASP.NET Images Using GDI+ Dynamically.

Here is what our final image will look like:

In my code-in-front, I have this:

<asp:Image ID="Image1" runat="server" /> 
<asp:Button ID="Button1" runat="server" Text="Button" />

In the code-behind I make sure to import:

Imports System.Drawing
Imports System.Drawing.Imaging

You may add this to your Page_Load or a button click event or some method you call:

Dim fileNameFrom As String = Server.MapPath("~/Images/PiperAtComputer.jpg")
Dim fileNameTo As String = Server.MapPath("~/Images/test2.jpg")
TextOnImage("Programming Is Fun!", fileNameFrom, fileNameTo)
Image1.ImageUrl = "~/Images/test2.jpg"

From the above, you see that to call our TextOnImage method, pass in a path from your root directory.

Protected Sub TextOnImage(ByVal textString As String, _
ByVal fileNameFrom As String, _
ByVal fileNameTo As String)

Dim Bmp As Drawing.Bitmap = Drawing.Bitmap.FromFile(fileNameFrom)

Using graphicsImage As Graphics = Graphics.FromImage(Bmp)
Dim typeFont As New Font("Arial", 8, FontStyle.Bold)' get height of current image
Dim height As Integer = Bmp.Height
' start string in 2 pixels from left and 15 pixels up from the bottom of the image
Dim leftMargin As Integer = 2
Dim bottomMargin As Integer = height - 15

graphicsImage.DrawString(textString, typeFont, Brushes.WhiteSmoke, leftMargin, bottomMargin)
Bmp.Save(fileNameTo, ImageFormat.Jpeg)

End Using
Bmp.Dispose()

End Sub

Other examples show how to create a new image from text.

Dynamic ASP.NET Text Image (C#) - This shows how to take text and display it as an image. Within this article, a reader posts a message how to do this with a transparent background (VB) which he altered after viewing this code (C#). Another readers shows how to display an image in an image control.

Programmatically add text to an image (C#)

May your dreams be in ASP.NET!

P.S. Some other imaging urls of interest:

Displaying Dynamically Generated Images (C#) - I downloaded this zip project and it works with 3.5 framework. The demo zooms and enlarges an image of a pineapple.

Graphics in VB.NET - Articles, Resources, Downloads, Blogs, Book Chapters, Tutorial, Source code

GDI+ & Graphics in C# - Articles, Resources, Downloads, Blogs, Book Chapters, Tutorial and Source code

Getting Started with GDI+ in C# Applications

GDI+ in VB.NET Tutorial for Beginners

Opening and viewing Images and Text files

Image Conversion Utility in C#

Resizing ASP.NET Images Using GDI+ Dynamically

nannette — Tue, 13 Jan 2009 14:38:00 GMT

In ASP.NET, you may easily resize images without using a third-party control. Whether reducing or enlarging, or creating a thumbnail image, ASP.NET is your oyster.

I'd like to review a solution by Alex Hildyard and demonstrate his custom ImageResize class in action. I'll provide a zip file for you to download with both my UI layer and Alex's ImageResize class project.

Go Picture Crazy: Resize Images Using GDI+ (C#) provides a tutorial and zip file and shows how to avoid using the GetThumbnailImage method to manipulate the size of an image and instead use the ImageResize class created by author, Alex Hildyard, who explains:

"The problem is, certain kinds of image formats (for example, JPEG) may already include embedded thumbnails, and under these circumstances GetThumbnailImage() just extracts the image's existing thumbnail and scales it to the proportions you specify, rather than generating a new bitmap by resampling the original image. In fact, many digital cameras will generate and embed a thumbnail automatically whenever you take a picture, so that you can quickly browse through any pictures you've taken on the camera itself."

In my example of using his class (VB.NET), we are going to create a proportionate resized image by pixels and save it to a file, and also create a proportionate resized image by percent and save it to an output stream to be used in the "src" tag of an image. Below is an example of our resuts:

To use the zip, within your original web project, simply go to File / Add Existing Project, and select the ImageResize.csproj. Using Alex's original zip, I right-clicked the project, selected Properties, and from the Application tab, changed the Target Framework to 3.5. Then in your web project, be sure to add this project to your references.

In my web form aspx page within my web application, I added this to the code-in-front:

<asp:Image ID="Image2" runat="server" /> 
50 pixels high, saved to a file. 
<asp:Label ID="Label2" runat="server" Text=""></asp:Label>
 
 
<asp:Image ID="Image3" runat="server" /> 
10 percent high, saved to an output stream. 
<asp:Label ID="Label3" runat="server" Text=""></asp:Label>

In the code-behind, I added this:

Imports ImageHelper
Imports System.Drawing.Imaging
Imports System.Drawing

Partial Class _Default
Inherits System.Web.UI.Page Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

If Not Page.IsPostBack Then
LoadImage()
End If

End Sub

Private Sub LoadImage() Dim filepathFrom As String = Server.MapPath("~/Images/DSCF0015.JPG")
Dim filepathTo As String = Server.MapPath("~/Images/test1.JPG")

Dim o As New ImageResize()
o.File = filepathFrom
o.Height = 50
o.UsePercentages = False
o.GetThumbnail().Save(filepathTo, ImageFormat.Jpeg)
Image2.ImageUrl = "~/images/test1.jpg"
Label1.Text = GetImageValues(filepathFrom)
Label2.Text = GetImageValues(filepathTo)
Image3.ImageUrl = "ImageResizer.aspx?filepath=" & filepathFrom & "&height=10&usepercent=true"
Label3.Text = "Width: 283 Height: 212"

End Sub

Protected Function GetImageValues(ByVal fileName As String) As String

Dim Bmp As Drawing.Bitmap = Drawing.Bitmap.FromFile(fileName)
Dim labelString As String = String.Empty
Dim height As Integer = Bmp.Height
Dim width As Integer = Bmp.Width
Bmp.Dispose()
labelString = "Width: " & width.ToString & " Height: " & height.ToString
Return labelString End Function

End Class

In the LoadImages method, put your path to the existing file and path to the new file. If you set UsePercentages to True, 50 will equal 50% of the image height, and if False, 50 will be 50 pixels high.

Notice Image2 is loaded on the page within the codebehind. If you want to embed the resizer within your src url, as done with Image3, simply create another web form, in my example I named it "ImageResizer." Add nothing to the code-in-front, and in the code behind, add this:

Imports ImageHelper
Imports System.Drawing.Imaging

Partial Class ImageResizer
Inherits System.Web.UI.Page

Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
LoadImage()
End Sub

Private Sub LoadImage() Dim filepath As String = Request.QueryString("filepath")
Dim height As String = Request.QueryString("height")
Dim usePercent As String = Request.QueryString("usepercent")

If usePercent = String.Empty Then
usePercent = "false"
End If

If filepath <> String.Empty Then

Dim o As New ImageResize()
o.File = filepath
o.Height = CInt(height)
o.UsePercentages = CBool(usePercent)
o.GetThumbnail().Save(Response.OutputStream, ImageFormat.Jpeg)

End If
End Sub End Class

Notice how the dynamic values are added to the query string in the original Image3.ImageURL and retreived in the ImageResizer LoadImage() method:

Image3.ImageUrl = "ImageResizer.aspx?filepath=" & filepathFrom & "&height=10&usepercent=true"

You may download the complete zip file: ImageEdit.zip

The ImageEdit.zip file also contains the source code for Image Text using GDI+: Creating an Image from Text or Adding Text to an Existing Image.

May your dreams be in ASP.NET and your images resized for the web!

Nannette Thacker

Setting Maximum Failures: Windows 2008 and IIS7 Application Pool Stopped

nannette — Thu, 08 Jan 2009 20:50:00 GMT

In IIS7, when your application pool errors so many times, it will automatically stop the application pool, thus taking your web application off line.

Service Unavailable

HTTP Error 503. The service is unavailable.

In your system events log, you will also have an error:

'A process serving application pool 'Pool Name' terminated unexpectedly...'

To restart it, go to the application pool in IIS7 and select the stopped pool and restart it.

This can be a real nuisance when you're debugging code and getting a lot of errors. To change the number of allowed failures, go to the application pool for the website you are working on in IIS7. Select it in the application pool list. Select "Advanced Settings" from the Actions panel on the right. Scroll down to Maximum Failures and change the number to a larger number. Mine was 5 by default and below I changed it to 50.

Then when you're done debugging/developing, change it back to a lower number as desired.

This is great because you can create a pool for different applications and only increase this setting on the application that you're working on that is causing the failures. So be sure to assign your "buggy" application to its own pool, rather than having it share a pool with your "behaved" applications.

May your dreams be in ASP.NET!

Nannette Thacker

Treeview Datasource for Linq to Entities versus a SQL Command in Code-Behind versus Code-In-Front

nannette — Wed, 31 Dec 2008 14:57:00 GMT

In this example, I'll show the differences between populating a Treeview using Linq to Entities, versus a SQL Command in Code-Behind using a function, versus Code-In-Front using a SelectCommand.

In creating a Treeview control, I found some differences in assigning the datasource. I list 3 different methods. In my example treeview, I am getting the menu name, preceded by the numeric list order. (This treeview is used for admin purposes to list all menu items, including menu dividers, so they can be selected and populate a form for editing of the menu item, thus the Home item #3 shows a --- to represent an editable menu divider.)

To help you understand what we're populating, our finished admin treeview will look like this:

Here is my TreeView (I happen to be using the Telerik Treeview, but hopefully enough will be applicable to the .net treeview. Feel free to let me know any discrepancies for our readers!):

<telerik:RadTreeView ID="tvMenu" runat="server">
</telerik:RadTreeView>

1) Populating with a Datasource and SelectCommand in the code-in-front:

<asp:SqlDataSource ID="SqlDataSource1"
runat="server"
ConnectionString="<%$ ConnectionStrings:MyConnectionString %>"
SelectCommand="SELECT * FROM [myMenu]">
</asp:SqlDataSource>

Codebehind:

With tvMenu .DataSourceID = "sqldatasource1" ' if defined a datasource in the code-in-front
.DataFieldID = "menuId"
.DataFieldParentID = "parentMenuId"
.DataTextField = "menuName"
.DataValueField = "menuId"
.CausesValidation = False
.Height = 300
.DataBind()
.ExpandAllNodes()

End With

Notice in the above example, we use a string with the datasource name from the code in front to define the datasourceID.

Our NodeDataBound looks like this:

Protected Sub tvMenu_NodeDataBound(ByVal sender As Object, ByVal e As Telerik.Web.UI.RadTreeNodeEventArgs) Handles tvMenu.NodeDataBound

Try

Dim item As RadTreeNode = e.Node

Dim dataRow As DataRowView = CType(e.Node.DataItem, DataRowView)
item.Text = dataRow("listorder").ToString & " " & _
item.Text

Catch ex As Exception
SendError(ex.Message)
End Try

End Sub

Our dataRow("listorder") should be wrapped in a function that checks for nulls. But in this example I'm simply converting it to string.

2) Populating a Datasource in our CodeBehind:

In this example, remove the datasource in the code-in-front. We'll define it programmatically in the codebehind:

Dim oMenuAdo As New MyMenuAdo()
Dim sqldatasource1 As New SqlDataSource
sqldatasource1.SelectCommand = oMenuAdo.GetAllMenusQueryString()
sqldatasource1.ConnectionString = GetMyConnectionString()

With tvMenu
.DataSource = sqldatasource1 ' if defined a datasource in the code-behind

... the rest remains the same as the first example, including the NodeDataBound...

Notice in the above, we use the name of the datasource, rather than the string name.

The GetMyConnectionString() function simply retrieves the connection string from the ConfigurationManager.AppSettings.

Our GetAllMenusQueryString() looks like this simply returns our query string:

Public Function GetAllMenusQueryString()
Dim sql As String = "SELECT * FROM [myMenu] order by listOrder"
Return sql
End Function

3) Populating with a Linq to Entities Datasource in our CodeBehind:

In our third example, we will define our datasource as an object:

Dim oMenuLinq As New MyMenuLinq()
With tvMenu
.DataSource = oMenuLinq.GetAllMenusDatasourceLinq() ' if defined a datasource as an object

... the rest of our tvMenu remains the same...

Our GetAllMenusDatasourceLinq looks like this:

Public Function GetAllMenusDatasourceLinq() As IEnumerable(Of myMenu) Dim query As IEnumerable(Of myMenu) = Nothing
Try

query = (From m In oEntities.myMenu _
Order By m.listOrder _
Select m)

Catch ex As Exception
End Try Return query
End Function

Our NodeDataBound must be updated to cast to the object's type instead of a DataRowView:

Dim item As RadTreeNode = e.Node

' with linq datasource, cast to my object's type
Dim dataRow As myMenu = DirectCast(e.Node.DataItem, myMenu )
item.Text = dataRow.listOrder.ToString & " " & item.Text

If I've made any mistakes, please feel free to educate me!

May your dreams be in ASP.NET!

Nannette Thacker

ADO.NET Linq to Entities versus Linq to SQL

nannette — Wed, 17 Dec 2008 18:45:00 GMT

I recently did a project using LINQ to SQL. I decided to convert it to the ADO.NET Linq to Entities model instead. It was fairly easy to convert with a few gotchas. I will list the changes here:

Linq to SQL	ADO.NET Linq to Entities
Creating a Model: Add New Item: Linq to SQL Classes	Creating a Model: Add New Item: ADO.NET Entity Data Model
query = _ (From m In dc.Menu _ Where m.menuId = menuId _ Select m).SingleOrDefault() SingleOrDefault is not supported in the current Entities releases (talk has it that it will be added in future releases). So use FirstOrDefault() in your Linq to SQL if you want your code to be forward compatible with Entities.	query = _ (From m In dc.Menu _ Where m.menuId = menuId _ Select m).FirstOrDefault()
Linq to SQL Deletion and Submitting Changes: Dim dc As New MyEntities() Dim menuDetail = _ (From md In dc.Menu _ Where md.menuId = menuId _ Select md).FirstOrDefault If Not menuDetail Is Nothing Then dc.Menus.DeleteOnSubmit(menuDetail) dc.SubmitChanges() End If	Linq to Entities Deletion and Submitting/Saving Changes: Dim dc As New MyEntities Dim menuDetail = _ (From md In dc.Menu _ Where md.menuId = menuId _ Select md).FirstOrDefault If Not menuDetail Is Nothing Then dc.DeleteObject(menuDetail) dc.SaveChanges() End If
dc.Menu.InsertOnSubmit(myRecord)	dc.AddToMenu(myRecord)

Also, the Linq to SQL messes with the "s" on the end of table names and Linq to Entities does not.

If I've made some mistakes, feel free to educate me. :)

Thanks to the Experts at Experts-Exchange for their help!

May your dreams be in ASP.NET!

Nannette Thacker

ADO.NET Entities Tutorials

nannette — Mon, 08 Dec 2008 14:30:00 GMT

I have been working with the ADO.NET Entities Data Model for ORM and I am very impressed. I'd been working with Data Sets and Table Adapters, so was excited about diving into the new release of ADO.NET Entities Data Model.

I found some excellent tutorials published in October 2008 (so they're fairly recent) to help get you started and want to share them with you.

Anand Thakur shares three C# tutorials:

Getting started with ADO.NET Entity Framework in .NET 3.5

Getting started with ADO.NET Entity Framework in .NET 3.5 - Part II

Getting started with ADO.NET Entity Framework in .NET 3.5 - Part III

I was able to follow along and whip together a quick VB version using my own tables. (You can do that assuming you know both C# and VB.) But in other words, it's a well thought out, documented set of tutorials.

Now what I particularly like about Anand's tutorials is that he caters to the very beginner. For instance, he takes you step by step through creating a 3-tier web application and projects, first by creating a windows class library and adding the ADO.NET Entities Data Model.

Then he shows you how to create the service layer project and how to add references. And finally the web site itself and adding references. If you've never created a three-tier project, this tutorial is an excellent walk-through.

Another tutorial by Wriju Ghosh covers tables with relationships:

ADO.NET Entity: Insert Update and Delete with Relationship

Also see: ADO.NET Entity: Insert Update and Delete

Wriju has also written numerous other blog posts on ADO.NET.

Now let me backup for those who are new to programming ASP.NET. If you're new to ADO.NET, maybe you should review some tutorials on ADO.NET as well. I recommend Joe Mayo's C# tutorial:

Lesson 01: Introduction to ADO.NET

There are additional lesson links at the bottom of this lesson. His objectives are to help you:

Learn what ADO.NET is.

Understand what a data provider is.

Understand what a connection object is.

Understand what a command object is.

Understand what a DataReader object is.

Understand what a DataSet object is.

Understand what a DataAdapter object is.

May your dreams be in ASP.NET!

Nannette Thacker

P.S. I just found this great 7-part tutorial by mendhak, which also includes information on Insert, Update, and Delete with Stored Procedures.

ADO.NET Entity Framework Tutorial and Basics

Enjoy!

Property: Visual Studio Tip

nannette — Fri, 05 Dec 2008 15:38:00 GMT

In Visual Studio, when you create a new Property, you're likely aware that as you type, intellisense will allow you to type the property name and type and upon hitting enter, it prepopulates the Property as below:

But are you aware that if you type the word "Property" followed by the TAB key, that VS will provide you with this slick little Property template:

Once the template is loaded, you may now edit the green highlighted areas and tab to the next green area, etc. Once you change the private variable name at the top, it will also change the values within the Property. Once you tab to the "String" type and change it, it will update the other "String" types as well:

Anyway, pretty slick. If you didn't know already, give it a shot.

May your dreams be in ASP.NET!

Nannette