How to return matching value in textbox? - vb.net

Question

I have a combo box that is populated by a csv. In my csv, I have 3 columns, the first column is id #s.

Answer 1

Maybe you can try ValueMember.
This is an example :
public partial class Form1 : Form
{
List<Student> listStudents = new List<Student>();
public Form1()
{
InitializeComponent();
listStudents.Add(new Student(101, "name1", "male"));
listStudents.Add(new Student(102, "name2", "female"));
listStudents.Add(new Student(103, "name3", "female"));
listStudents.Add(new Student(104, "name4", "male"));
var maleStudentList = listStudents.Where(student => student.gender == "male").ToList();
comboBox1.DisplayMember = "name";
comboBox1.ValueMember = "id";
comboBox1.DataSource = maleStudentList;
}
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
label1.Text = ((Student)comboBox1.SelectedItem).id.ToString();
}
}
class Student
{
public int id { get; set; }
public string name { get; set; }
public string gender { get; set; }
public Student(int id, String name, String gender)
{
this.id = id;
this.name = name;
this.gender = gender;
}
}
Source : https://social.msdn.microsoft.com/Forums/windowsmobile/en-US/1a978579-1938-44cd-aab3-d1964548a814/why-dont-comboboxs-item-have-a-tag-property?forum=csharpgeneral

Answer 2

What I would do is create a class to represent a row in the CSV file and have your properties represent the columns. The reason for this is because you could then convert the CSV file to a list of your class and then bind the ComboBox to the list.
When you bind your ComboBox you will set the DisplayMember to the Description and the ValueMember to the Id.
I'm not sure how you're reading the CSV file nor do I know the name of your second column, so I'm making some assumptions in my example, but it should plenty to go off of. Please keep in mind, that there are likely better ways of parsing CSV files, this is just an quick example to demonstrate how the binding would work.
This is how you'd define your class:
Public Class CsvRow
Public Property Id As Integer
Public Property Column2 As String
Public Property Description As String
End Class
This is how you'd read the CSV and bind the objects.
Dim lines() As String = IO.File.ReadAllLines("my-file.csv")
Dim rows As New List(Of CvsRow)()
For Each line In lines
Dim cells() As String = line.Split(","c)
Dim row As New CvsRow()
If (cells.Length = 3 AndAlso Integer.TryParse(cells(0).Trim(), row.Id) Then
row.Column2 = cells(1)
row.Description = cells(2)
rows.Add(row)
End If
Next
Dim binder As New BindingSource()
binder.DataSource = rows
ComboBoxDescription.DataSource = binder.DataSource
ComboBoxDescription.DisplayMember = "Description"
ComboBoxDescription.ValueMember = "Id"
Now in the ComboBox's SelectedValueChanged you can get the SelectedItem and convert it back to a CsvRow to get the properties:
Private Sub ComboBoxDescription_SelectedValueChanged(sender As Object, e As EventArgs) Handles ComboBoxDescription.SelectedValueChanged
If (ComboBoxDescription.SelectedItem IsNot Nothing) Then
Dim row As CvsRow = DirectCast(ComboBoxDescription.SelectedItem, CvsRow)
'row.Id and row.Description are now available
End If
End Sub

Answer 3

I made a class called Product with 3 properties. I guessed that the middle column would be the name of the product. When you add an object to a combo box, the combo will call .ToString on the object to get what to display. I provided an override of the .ToString method to tell the combo to display the name property of the Product object. Finally, I replaced the default constructor with a parameterized one to make creating the Product with all its properties easier.
In the FillCombo method (probably called from the Form.Load) I read your data file. You can change that to however you are reading the file. The important part is where you call the New method of the product adding each of the properties from your file. The entire Property object will all its properties are added to the combo box.
The SelectedIndexChanged event shows you how to retrieve the properties and display them wherever you want. To the combo box, it is an Object. You must cast it back to a Product to be able to access its properties.
Public Class Product
Public Property ID As Integer
Public Property Name As String
Public Property Description As String
Public Overrides Function ToString() As String
Return Name
End Function
Public Sub New(iID As Integer, sName As String, sDesc As String)
ID = iID
Name = sName
Description = sDesc
End Sub
End Class
Private Sub FillCombo()
Dim lines = File.ReadAllLines("data.csv")
For Each line In lines
Dim props = line.Split(","c)
Dim p As New Product(CInt(props(0)), props(1), props(2))
ComboBox1.Items.Add(p)
Next
End Sub
Private Sub ComboBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged
Dim p = DirectCast(ComboBox1.SelectedItem, Product)
TextBox1.Text = p.ID.ToString
TextBox2.Text = p.Description
End Sub