Posts tagged ‘VB’

HTTP post in VBA

I have some very nice C# .NET web services that I created and use from some web sites, .NET desktop applications, and iOS apps. But of course, this is not a wide enough range of technologies that I have to deal with, so I needed to figure out how I could call my web service from within an Access database using Visual Basic for Applications (VBA).

The web service just takes in a couple of form variables, chugs through the database looking for the matching records, and returns a string with the pertinent data. Here is the VBA code that I put together to accomplish this task:

Sub Method1()
    Set objHTTP = CreateObject("WinHttp.WinHttpRequest.5.1")
    URL = ""
    objHTTP.Open "POST", URL, False
    objHTTP.setRequestHeader "Content-type", "application/x-www-form-urlencoded"
    objHTTP.send "formVariable1=value1&formVariable2=value2"
    If objHTTP.Status = 200 Then
        MsgBox objHTTP.responseText
        MsgBox "Failed at getting response from web service:" & objHTTP.Status
    End If
End Sub

The response text is being sent to a message box, but you could just as easily return that string, or better yet, use an XML parser to dig into the data for just what you need. Perhaps I will save that code for another post later.

BTW, Happy Birthday to Julie Newmar, by far the best Catwoman from any Batman live action or animated TV show or movie.

Easy way to format the time difference between two dates

In converting my VB6 code over to VB.NET, I was looking for an easy way to take the different between two DateTime items and display in hours and minutes.  The TimeSpan gives a nice structure to dive into the difference and see exactly the interval, but I was hoping to find a way to output this in the same way that you can use the ToShortTimeString method of DateTime.

As it turns out, I found a posting by Jay Barlow that mentions converting the time different to a date time, and then using a custom format string to do the work so that I wouldn’t have to.  Here is my new VB.NET code, where rec is a class that includes the start and end date and duration is a string that holds the information to be displayed:

If rec.endDate IsNot Nothing Then
    Dim ts As TimeSpan = CDate(rec.endDate).Subtract(rec.startDate)
    Dim dt As DateTime = DateTime.MinValue.Add(ts)
    duration = "Event duration: " + dt.ToString("H:mm")
End If

Oh, and one more thing. Am I the only one in the world that thinks that iPad is the worst product name in history? Sure, it is so close to iPod so as to create brand recognition and draw comparisons, but I would just wonder what kind of names were shot down, and if any of them did not begin with the letter i.

By the way, Happy (Belated) Australia Day.

VB.NET radio button groups act differently than VB6 radio button groups

The few dozen remaining WinForms developers left on this planet may have noticed that, for some reason, a group box with radio buttons in it as designed in the Visual Studio 2008 environment will have the first radio button of the first group box automatically selected when the form comes up, even though all of the radio buttons have their Checked property set to false in the design environment.  It never used to do this in VB6, as when you ran the application, the group of radio buttons would have no members selected.

The problem manifests itself when you are trying to perform additional tasks in the CheckedChanged event of the radio buttons when the user selects one of the radio buttons, since the first radio button is being automatically selected.

I asked this question on Stack Overflow, and got a couple of replies. The one that I finally used to solve the problem was to set the Checked property of the radio buttons to false in the form’s Shown event, which I had never used before. By doing this, the first radio button was no longer automatically showing up checked.

One other thing that I had to do in addition was to cast the sender into a RadioButton and look at the Checked property of the clicked radio button in the CheckedChanged event, as that event is fired for radio buttons both being turned on and also turned off.

Oh, and happy National English Toffee Day!

VB.NET ListBox does not scroll all the way to the bottom when setting SelectedIndex

I have a standard Windows list box that I am using in my Visual Basic .NET application. I am adding records into this list box by binding it to a data source that reads records from a local database and uses a display member in the class to chew on the record and spit out the text. Then, I logically want to see if there are records in this newly minted list box, and if so, set the selection to the last record in the list, which should scroll to the bottom of the list in the event that there are more records to display than lines in the list box. The code:

lstRecords.DataSource = DataLayer.GetRecords(theID)
If lstRecords.Items.Count > 0 Then
    lstRecords.SelectedIndex = lstRecords.Items.Count - 1
End If

Unfortunately, this code does not work 100% as expected. If there are more records than rows available in the list box, the final row does get selected, as the blue selection bar lands on that row. Once you scroll the list down one row to see it. For some reason, the scrolling down of the list box comes up one row short when done this way, no matter how many rows beyond the limit of the list box are added.

I tried everything I could think of, mostly manipulating the properties of the list box to see if some combination worked. I called the Update and Refresh methods, set the TopIndex and IntegralHeight properties, and lots of other things that did not have any effect.

I finally decided to try to set the SelectedIndex property in a timer event. The timer is initially disabled with an interval of 5 ms, and instead of setting the SelectedIndex property as shown in the line above, it enables the timer. And here is the code that executes when the timer fires:

tmrScrollToEnd.Enabled = False
lstRecords.SelectedIndex = lstRecords.Items.Count - 1

And of course, for some reason that escapes me, this now works. Perhaps it is because the setting of the SelectedIndex is moved outside of the Form Load code, which is where the code above was being executed. If anyone has any ideas, I would love to hear them, but I am glad that it is now working.