[RESOLVED] Issues when writing to a File using StreamWriter

[paintman]

I have tried to find someone with the same issue but none are what I am looking for.

I am using a stream writer to type a string into a file (not a text file, just a "File" with no .txt or any extension) and the data writes to the file, but as soon as i open the file and view the data it erases it upon closing the file. I use the same method to write to an actual .txt file and there is no issue, so i am wondering if it is because it is a "nonlabeled" file. Though it has to be that way so another program in LabView can open the data.

It is pretty frustrating and i can not figure out what is causing it to do that. I posted my code below (idk if it is formatted correctly this is my first post)

    Private Sub Testing_Values_DataChanged(sender As Object, e As Drivers.Common.PlcComEventArgs) Handles Testing_Values.DataChanged
        Dim mydriver As New EthernetIPforCLXCom
        mydriver.IPAddress = "111.111.1.111"  'NOT SUBJECT TO CHANGE nor my real IP address

        Dim UNLOADCARRIER_V As String = mydriver.Read(UNLOADCARRIER)
        UNLOADCARRIER_N = Convert.ToInt32(UNLOADCARRIER_V)
        Dim UNLOADCOLOR As String = mydriver.Read(($"{"Carrier_Info["}{UNLOADCARRIER_V}{"].Paint_Color"}"))
        Dim UNLOADNUMBER As String = mydriver.Read(($"{"Carrier_Info["}{UNLOADCARRIER_V}{"].Part_Number"}"))
        Dim UNLOADNAME As String = mydriver.Read(($"{"Carrier_Info["}{UNLOADCARRIER_V}{"].Name"}"))
        'END
        If UNLOADCOLOR <> "0" Then
            If UNLOADNUMBER <> String.Empty Or UNLOADNUMBER <> "" Then
                If UNLAST_CAR <> UNLOADCARRIER_N Then
                    testdata = ($"{DateTime.Now.ToString("h:mm:ss.fff tt M/dd/yyyy")},{"P"}")
                    valuedata_unload = ($"{UNLOADNUMBER},{Date.Now.ToShortDateString},{shift}")
                    Using sw4 As New StreamWriter(testfile1, fileExists4)
                        sw4.WriteLine($"{testdata}")
                        sw4.Close()
                    End Using
                    UNLAST_CAR = UNLOADCARRIER_N
                End If
            End If
        End If
    End Sub

[dday9]

Why don't simply use IO.File.AppendAllText (documentation) and omit the extension? E.g.

Try
    Dim fileLocation = "some-file-no-ext"
    Dim data = "Change me to something meaningful."
    IO.File.AppendAllText(fileLocation, data & Environment.NewLine)
Catch ex As Exception
    ' do something with the exception
    Console.WriteLine(ex.Message)
End Try

[paintman]

I tried using the IO.File.AppendAllText but the same issue still occurred. I rewrote labview code to read a .txt file and the issue seems to be resolved. I am not sure if it was just a file incompatibility for the stream writer or if my labview code was somehow erasing the data.

[dday9]

My guess is the latter.

[dbasnett]

I tried to emulate what you say is happening. I think this captures what you said.

        Dim path As String = Environment.GetFolderPath(Environment.SpecialFolder.Desktop)
        path = IO.Path.Combine(path, "FOOfile")
        Dim alpha As String = "abcdefghijklmnopqrstuvwxyz"
        Using sw As New IO.StreamWriter(path, True)
            For Each c As Char In alpha
                sw.Write(c)
            Next
        End Using

When I opened 'FOOfile' (no extension) it contained,

abcdefghijklmnopqrstuvwxyz

After running again it the file contained,

abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz

[Shaggy Hiker]

If you can open that file in some other program, and the data is there, but when you open it with LabView, it is first there, then goes away upon closing, then it's the labview that is doing it. I don't know what labview is, or how it works, but there are several ways this could be happening. For one thing, the other part of the file (if there is another part) might contain some kind of file length information, so all that gets written is that length, thereby ignoring your extra stuff. More likely, though, it is reading everything in, then writing everything back out...but not quite everything, as it's forgetting about your extra stuff.

Either way, I think you've determined that the issue isn't due to writing to the file. That part appears to be working correctly, it's something about what happens next that is screwing up the file.

[paintman]

Hello all,

So I removed the labview section where it views the code and just let the vb code write to the file, and I am still having an issue with the text file retaining the data.

VB will append the file like its suppose to but it will randomly erase the entirety of the file and begin writing again. I tested to make sure that the code which checks the file path to ensure the file exists works, since if the file isnt there it will create a new one. I set the fileexist variable to true so it will always assume the file is valid. Yet I am still having issues, I tried using the IO.File.AppendAllText instead of stream write and the situation still happens... I am at a loss as to what is causing this.

I have multiple stream writers and this is the only one I am having problems with. Which is crazy because I copied and pasted the codes since I knew that it works, just not with this one. I think I have narrowed it down to being something within the VB code, I am just not sure what.

[paintman]

This was the way I used the AppendAllText

    Private Sub Testing_Values_DataChanged(sender As Object, e As Drivers.Common.PlcComEventArgs) Handles Testing_Values.DataChanged
        Dim mydriver As New EthernetIPforCLXCom
        mydriver.IPAddress = "111.111.1.111"  'NOT SUBJECT TO CHANGE
        'Carrier value at load station
        fileExists4 = True

        Dim UNLOADCARRIER_V As String = mydriver.Read(UNLOADCARRIER)
        UNLOADCARRIER_N = Convert.ToInt32(UNLOADCARRIER_V)
        Dim UNLOADCOLOR As String = mydriver.Read(($"{"Carrier_Info["}{UNLOADCARRIER_V}{"].Paint_Color"}"))
        Dim UNLOADNUMBER As String = mydriver.Read(($"{"Carrier_Info["}{UNLOADCARRIER_V}{"].Part_Number"}"))
        Dim UNLOADNAME As String = mydriver.Read(($"{"Carrier_Info["}{UNLOADCARRIER_V}{"].Name"}"))
        'END
        If UNLOADCOLOR <> "0" Then
            If UNLOADNUMBER <> String.Empty Or UNLOADNUMBER <> "" Then
                If UNLAST_CAR <> UNLOADCARRIER_N Then
                    testdata = ($"{DateTime.Now.ToString("h:mm:ss.fff tt M/dd/yyyy")},{"P"}")
                    valuedata_unload = ($"{UNLOADNUMBER},{Date.Now.ToShortDateString},{shift}")
                    Try
                        IO.File.AppendAllText(testfile1, testdata & Environment.NewLine)
                    Catch ex As Exception
                        Console.WriteLine($"{"Data failed to save:"}{ex}")
                    End Try
                    UNLAST_CAR = UNLOADCARRIER_N
                End If
            End If
        End If
    End Sub
End Class

[OptionBase1]

We can only speculate, since you are only providing part of your code. You obviously have other relevant code you haven't posted, since, for example, you don't show any code where your variable of testfile1 is being populated.

You say you have multiple stream writers, and I'm assuming you mean that you have them in use inside of this program. The most likely scenario is that some other code that you haven't posted is responsible for either deleting the file completely or creating a new empty file in its place. And one possible cause of that is because, as you said, you "copied and pasted" this code that worked, and maybe you should have changed some variable names in the "pasted" code, but you didn't, and so now you are accidentally reusing a global variable (like testfile1) somewhere else, when you should have created some new global variable (or used function parameters, etc).

Good luck.

[paintman]

We can only speculate, since you are only providing part of your code. You obviously have other relevant code you haven't posted, since, for example, you don't show any code where your variable of testfile1 is being populated.

You say you have multiple stream writers, and I'm assuming you mean that you have them in use inside of this program. The most likely scenario is that some other code that you haven't posted is responsible for either deleting the file completely or creating a new empty file in its place. And one possible cause of that is because, as you said, you "copied and pasted" this code that worked, and maybe you should have changed some variable names in the "pasted" code, but you didn't, and so now you are accidentally reusing a global variable (like testfile1) somewhere else, when you should have created some new global variable (or used function parameters, etc).

Good luck.

The code is quite long, I don't mind posting it in its entirety, I have double checked all the variables and they are all where they are suppose to be. I renamed them to make it easier to tell which file corresponds to each file.

[OptionBase1]

We need to see all the code that does any sort of file interaction.

[paintman]

I have attached the full length of the code, it was written using Visual Studios 2022

[OptionBase1]

I posit that your code is causing the problem.

You have this as a Form level variable:

Public testfile1 As String 'this is a variable since the file will change each year

Then you have this a few lines later:

Public testfileExists As Boolean = File.Exists(testfile1)

I would imagine that testfileExists will always evaluate to False when the program is first loaded, because testfile1 hasn't been assigned a value yet when that second line is executed.

So, you need to shuffle stuff around. It might just be as easy as changing that second line to:

Public testfileExists As Boolean

And then in MainForm_Load, do this:

        testfile1 = ($"{testfile_folder}\{Date.Now.ToString("yyyy")}_P001.txt")
        testfileExists = File.Exists(testfile1)  ' Add this line

[paintman]

I posit that your code is causing the problem.

You have this as a Form level variable:

Public testfile1 As String 'this is a variable since the file will change each year

Then you have this a few lines later:

Public testfileExists As Boolean = File.Exists(testfile1)

I would imagine that testfileExists will always evaluate to False when the program is first loaded, because testfile1 hasn't been assigned a value yet when that second line is executed.

So, you need to shuffle stuff around. It might just be as easy as changing that second line to:

Public testfileExists As Boolean

And then in MainForm_Load, do this:

        testfile1 = ($"{testfile_folder}\{Date.Now.ToString("yyyy")}_P001.txt")
        testfileExists = File.Exists(testfile1)  ' Add this line

Its strange though since this issue only happens with the valuefile_load and the testfile1 but I will certainly give this a try! Thank you for the advice

[paintman]

This was my issue!! Thank you so much, this was driving me crazy. I appreciate everyone's help.