Write and read data from XML file through VB.Net at launch

Question

I started doing some applications in VB.Net in the past year and a half and despite all my research for an answer, nothing has worked fine enough for me, so here I am, asking my question.

I have an application which allows the user to save the following data in an XML file:

Custom name for the saved data above (inputted in a text box called txtName)
Email (inputted in a text box called txtEmail)
Password (inputted in a text box called txtPassword)

The XML file (with the name: appData.xml - see below for directory of executable file along with directory of xml file) looks like this template shown below. The xml file stores a total of 10 passwords and each password is being attributed an ID number. I have thought that I would need to attribute an ID number (from 01 to 10) to refer it in the code of my application. If there is an easier way to identify where to store the saved data, feel free to modify my xml file.

<?xml version="1.0" encoding="UTF-8"?>
<savedData>
    <savedPassword id="01">
        <name>Stored Name</name>
        <email>[email protected]<email>
        <password>storedPassword</password>
    </savedPassword>
    <savedPassword id="02">
        <name>Stored Name</name>
        <email>[email protected]<email>
        <password>storedPassword</password>
    </savedPassword>
    <-- Other data modules for ids 03 to 09 --!>
    <savedPassword id="10">
        <name />
        <email />
        <password />
    </savedPassword>
</savedData>

The XML is located in the following folder: C:\VelocityDK Codes\Password Manager and the application's executable is located in the following folder: [USERPROFILE]\Documents\VelocityDK Codes ("[USERPROFILE]" being the partial path to my documents folder on my Hard Drive). As I am quite new to XML handling in VB.Net (windows forms), I have no idea if the name of the form is needed to retrieve the data from the xml - but if it is, here it is: frmMain.

Sadly, I do not have enough experience in storing data from external data files and pulling that data from a file located in a completely different directory than the application file withing the load of the executable files, so I do not actually have any code to provide... Therefore, what I want to do is the following: I need to retrieve the data from my XML file at each launch automatically.

Is your problem you don't know to load an XML file? Or is it how to add code which is run at the program's start? Or is it that you don't know how to access a file in the file system in a different folder than the current directory? Please clarify. — Doc Brown
– Doc Brown, Commented Nov 22, 2019 at 21:36
You show some some, ahem, variations from the locations Microsoft say should be used for programs and data. Have a look at Environment.SpecialFolder Enum to see where things should be stored. Your own directory (i.e. you pick a sensible name) in ApplicationData or CommonApplicationData would be the ideal place to store the XML file. — Andrew Morton
– Andrew Morton, Commented Nov 22, 2019 at 21:41
@DocBrown I would need to know how I can read the data from the XML file from a different directory/folder. — Velocity DK
– Velocity DK, Commented Nov 22, 2019 at 21:42
@AndrewMorton Ok, I will take care of it a bit later on. Thanks for the advice. — Velocity DK
– Velocity DK, Commented Nov 22, 2019 at 21:43

djv · Accepted Answer · 2019-11-22 22:54:55Z

Use XML Serialization. IMO this is superior to using XDocuments in most cases. You will have an object with children which represent your xml file contents. You can iterate of the children, and everything is strongly-typed.

Start by creating VB.NET classes to represent your data

Option Strict On

Imports System.IO
Imports System.Xml.Serialization

<XmlRoot("savedData")>
Public Class SavedData
    <XmlElement("savedPassword")>
    Public Property SavedPasswords As List(Of SavedPassword)
End Class

Public Class SavedPassword
    <XmlAttribute("id")>
    Public Property ID As Byte
    <XmlElement("name")>
    Public Property Name As String
    <XmlElement("email")>
    Public Property Email As String
    <XmlElement("password")>
    Public Property Password As String
End Class

Once you have that, reading the file into your classes is pretty simple. Use the following code

Dim filename = "filename.xml"
Dim data As SavedData
Dim serializer As New XmlSerializer(GetType(SavedData))
Using sr = New StreamReader(filename)
    data = CType(serializer.Deserialize(sr), SavedData)
End Using
For Each sp In data.SavedPasswords
    Console.WriteLine($"id: '{sp.ID}', name: '{sp.Name}', email: '{sp.Email}', password: '{sp.Password}'")
Next

The only thing you need to do is to set the correct filename instead of Dim filename = "filename.xml". If the path is fixed, you can simply hard-code it

Dim filename = "C:\VelocityDK Codes\Password Manager\filename.xml"

If the path can vary such as being based on the Environment.SpecialFolder Enum you can incorporate it into the assignment:

The executing assembly needn't be in the same folder as the xml file.

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