ASP.NET Prevent double-clicking of buttons

If you have a button that causes a record to be inserted into a table, you can sometimes run into duplicate records if the user happens to click the button twice (double-click).  This can be prevented by using javascript to disable the button as soon as the button is clicked the first time.  Use the following code:

<script>

    function disableButton() {
        document.getElementById("ID_OF_BUTTON").disabled = true;
    }

</script>

Then, use the OnClientClick property of the button to call this code:

<asp:Button ID="ID_OF_BUTTON" runat="server" Text="Click Me" OnClientClick="disableButton();" UseSubmitBehavior="false" />

NOTE: I have not used this on a form that has client validation, so I'm not sure how of if this would work in that situation.

Serialize .NET object to JSON

Let's say you have following classes:

Public Class Output
    Public Property Query As QueryDetails
End Class

Public Class QueryDetails
    Public Property Count As Integer
    Public Property Created As DateTime
    Public Property Lang As String
End Class

And let's also say you have created an object and have assigned values as such:

Dim MyQueryDetails As New QueryDetails With {.Count = 1, .Created = Now, .Lang = "en"}
Dim MyData As New Output
MyData.Query = MyQueryDetails

To "serialize" the object as JSON use the following code.  You will need to add a reference to the JSON.net library located at https://www.newtonsoft.com/json.

Dim Results As String = Newtonsoft.Json.JsonConvert.SerializeObject(MyData)
Console.WriteLine(Results)
'{"Query":{"Count":1,"Created":"2018-09-13T10:26:13.2004198-05:00","Lang":"en"}}

Call a REST API from .NET

To call a REST API using the "GET" ("POST" is beyond the scope of this article) HTTP verb, use the following code:

Using Client As New System.Net.WebClient

    Dim Results As String =
        Client.DownloadString("API URL")

End Using

This will populate the Results variable with the output of the web service call.  Almost invariably, this will be in the JSON format.  Note that all input is contained in query parameters in the API URL.

Now we need to get the JSON into a .NET object that can be easily read.  This process is called deserialization.  You can do this using native .NET classes, but oddly, Microsoft seems to prefer that you use the JSON.net library.  This can be downloaded at https://www.newtonsoft.com/json.

Next you will need to create a series of classes that correspond to the structure of the JSON output.  For example, if your output JSON looks like this:

{"query":{
    "count":1,
    "created":"2018-09-07T15:51:40Z",
    "lang":"en-US"
    }
}

You should create two classes like this:

Public Class Output
    Public Property Query As QueryDetails
End Class

Public Class QueryDetails
    Public Property Count As Integer
    Public Property Created As DateTime
    Public Property Lang As String
End Class

Then, simply write the following code to deserialize the JSON output into the .NET Output object:

Dim MyOutput As New Output
Newtonsoft.Json.JsonConvert.PopulateObject(Results, MyOutput)

All types of JOINS explained

I found this on Stack Exchange.  Brilliant!

Try Catches are not necessary for logging exceptions

I support a large system where there are try catches everywhere to log the exception.  See my post Simple and secure exception handling for .NET web applications for a better way.  I found an instance where instead of just removing the (unnecessary) try catch, I simply removed the line that logged the error and then threw the exception expecting the Application_Error event to log.  Unfortunately, the stack trace that was logged only indicated the line number of the Throw statement and not where the error actually occurred!  The lesson is, if you use a try catch, then log it right there.  If not, just get rid of the try catch completely.

Remove TFS source control from a .NET solution

Sometimes, you want to remove all TFS source control bindings from a solution.  This is helpful if you are moving the solution to a different TFS project or you want to use a different source control product.

First remove the .vssscc file from the solution folder, and the .vspscc file in each individual project folder.

Then, open up the solution file in Notepad.  Remove the following section completely:

 GlobalSection(TeamFoundationVersionControl) = preSolution
  SccNumberOfProjects = 2
  SccEnterpriseProvider = {########-####-####-####-############}
  SccTeamFoundationServer = https://tfs.yourdomain.com/tfs/my_collection
  SccLocalPath0 = .
  SccProjectUniqueName1 = MyProject\\MyProject.vbproj
  SccProjectName1 = MySolution
  SccLocalPath1 = MySolution
 EndGlobalSection

Add an Alpha Channel to GIMP Images to support transparency

A common task when using GIMP, is to remove the background of an image and make it transparent.  Use the fuzzy select tool to select the background.  An image must have something called an "alpha channel" in order to support transparency.  If the image already has an alpha channel, pressing the delete button will make the background transparent.  If it doesn't, pressing delete will do nothing while your frustration mounts.  Simply, select Transparency in the Layer menu and choose Add Alpha Channel.