Filter data in datagridview according to combobox in c#

As we have previously studied that datagridview is used for display rows and columns of data in a grid format in windows form. Mostly data are previously defined which are to be shown in datagridview. Sometimes we have to change the data on basis of some conditions.

In previous post we have learnt to bind a datagridview with search option and in else case all the data from database will bind to datagridview in C# language. In this post we will learn to bind datagridview with the selected index changed event of combobox in C#.

The selection changed event of combobox occurs when the value of selected index property changes. We are going to change our data of datagridview according to that changed value.

Let’s create a student class, which will be used to bind our datagridview, having some properties like below:

public class Student

{

public string Name { get; set; }

public int Age { get; set; }

public string Address { get; set; }

public string Branch { get; set; }

}

Create a new list of student that will be the data source of datagridview and insert some records in that list having branch CS or IT as I have inserted in my example using C# language. Set this list as a data source of datagridview.

dataGridView1.DataSource = studentList;

Now when we run this project all the records will be shown in datagridview. We want to change the data of datagridview according to selection changed event. So write the below code in selection changed event of combobox

if (comboBox1.SelectedItem != null)

{

string branch = comboBox1.Text;

var students = studentList.Where(a => a.Branch.Equals(branch));

dataGridView1.DataSource = students.ToList();

}

Run this project now and change the selection value of combobox to CS and we will show the data of datagridview have been changed as following image:

Change the selection value to IT and the data will be changed as following image:

Go for example

Find a control in windows forms

When we drag-n-drop controls in our designer file then we can easily access those controls in our code file directly by its name. But when we dynamically add some controls either in constructor or in load event of form then we can't access them directly in our code.

Let's have an example

• Add a textbox and a button using drag-n-drop operation on our form i.e. Form1.
• Leave the name of controls i.e. textBox1 and button1 as they are.
• Now in constructor add a new textbox dynamically having name "txtBox" with some properties like:
  
  
  TextBox txtBox = new TextBox();
  txtBox.Name = "txtBox";
  txtBox.Text = "dynamically added control";
  txtBox.Width = 250;
  txtBox.Location = new Point(10, 10);
  
  this.Controls.Add(txtBox);

In above code the Name property will be used to find this control. All the remaining properties are familiar to you as in our designer file. At the last we have added this textbox to the form, here the keyword this is pointing Form1.

This form will look like the following screenshot: 

 

In click event of button when we will try to access above controls then we notice that "textBox1" will be accessed by its name and "txtBox" will not accessed here.

To access these dynamically added controls we have to use a pre-defined method Find(). This method searches the controls by their name and builds an array as in below code.

Control[] controls = this.Controls.Find("txtBox", false);

foreach (var item in controls)

{

     TextBox txtBox = item as TextBox;

     if (txtBox != null)

        MessageBox.Show("control accessed");

}

In above set of code "controls" will hold the array of all the controls having name "txtBox". One by one we will access items of array and check the type of item. If type of item is TextBox then we found our textbox having name "txtBox".

As we know about naming standards of programming that two controls of the same name cannot exists. Keep in mind the above line, and we are sure that, there will only one control named “txtBox” of type TextBox.

Now we will access the above textbox in one line of code i.e.

TextBox txtBox1 = this.Controls.Find("txtBox", false).First() as TextBox;
if (txtBox1 != null)
 MessageBox.Show("control accessed");

When we run our project and click on button then our form look like this.