Question

This is my table structure 2 column rate chart and qty :

rate   chart   qty
1      -5       1
6     -10       2
11    -20       3

I have 3 fields on windows form

• 1 combobox
• 1 textbox
• 1 button

I fetch the ratechart column value through combobox, I have that code but my requirement is if user select 1-5 from combobox, then textbox he cannot enter more than 6 in textbox.

Same if user select 6-10 from combobox , then he cannot enter more than 12 in textbox

while he click on save button he get an error that qty is more..

thx in advance. please help me for this code

Answer 1

Assuming cmbRateChart.SelectedValue contains qty value with respect to RangeChart.

private void textBox_Validating(object sender, CancelEventArgs e)
{
    bool cancel = false;
    int number = -1;

    if (int.TryParse(this.textBox.Text, out number))
    {
        var validRange = Convert.ToInt32(cmbRateChart.SelectedValue) * 6;
        if (number <= validRange)
            cancel = false; //passed validation.
        else
            cancel = true; //failed validation, number is not in valid range

    }
    else
        cancel = true;//failed validation: text box is not a number
    e.Cancel = cancel;
}

Usage: Call this function to check the validation.

this.ValidateChildren(ValidationConstraints.Enabled);

Reference: Validation in Windows Forms