How to look for a specific amount of digits within texbox textChanged event in C#?

Question

In my Windows Form Application, I want to implement a feature where the user has to fill in the serial number of a product that is when matched with any product in the database, the product must appear in a grid. I want to do so using textbox textChanged event.

I am confused in figuring out that either I must prevent firing the textChanged event before the textbox value matches any value in the database. Is there any way to make the textbox expect a specific amount of text or number (my serial numbers are going to be fixed length - like 10001, 10002, 10003) before running the remaining code for showing product in the grid?

Answer 1

You can use TextLength property of the TextBox to get length of text. For example:

private void textBox1_TextChanged(object sender, EventArgs e)
{
    if (textBox1.TextLength < 5)
        return;

    //Send query to database
}

Note: As it's also mentioned by Jimi in the comments, it's good idea to set MaxLength of TextBox to prevent entering more text.