Replacing a single quote with two single quotes in a two-way bound textbox

Question

I have a WPF application that has a text box with a two-way binding. The XAML code looks like this:

<TextBox materialDesign:HintAssist.Hint="Name*" materialDesign:HintAssist.HintOpacity="10" materialDesign:HintAssist.Background="White" materialDesign:ValidationAssist.Background="White" materialDesign:HintAssist.Foreground="#FF002655" Style="{StaticResource MaterialDesignOutlinedTextFieldTextBox}" x:Name="txtboxFirstName" Width="260" TextChanged="txtboxFirstName_TextChanged">
<Binding Path="FirstName" UpdateSourceTrigger="PropertyChanged" Mode="TwoWay" Source="{StaticResource MyConfigs}">
    <Binding.ValidationRules>
        <local:TextBoxValidation ValidatesOnTargetUpdated="True"/>
    </Binding.ValidationRules>
</Binding>
</TextBox>

And the code behind looks like this:

private void txtboxFirstName_TextChanged(object sender, TextChangedEventArgs e)
{
    MyConfigs.FirstName = txtboxFirstName.Text;
    ((MainWindow)System.Windows.Application.Current.MainWindow).ValidIntroductionConfigs();
}

I am trying to do the following here:

1. If the user enters a single quote ' here, it should be replaced with '' in the MyConfigs.FirstName because otherwise it causes issues in SQL queries.
2. When the app is loaded up it takes up the value from the MyConfigs.FirstName configuration. And if that contains '', it should display them as '.

For example: I enter O'Brian here. Now, O'Brian should be saved as O''Brian in MyConfigs.FirstName however, when I load it up, it should display O'Brian which is the real name.

When I did this, it just kept on replacing ' with '' and made it something like O''''''Brian. It kept on going so I just kept on getting more single quotes.

private void txtboxFirstName_TextChanged(object sender, TextChangedEventArgs e)
{
    if (txtboxFirstName.Text.Contains("'"))
    {
        MyConfigs.FirstName = txtboxFirstName.Text.Replace("'", "''");
    }
    if (MyConfigs.FirstName.Contains("''"))
    {
        txtboxFirstName.Text = MyConfigs.FirstName.Replace("'", "''");
    }
    MyConfigs.FirstName = txtboxFirstName.Text;
    ((MainWindow)System.Windows.Application.Current.MainWindow).ValidIntroductionConfigs();
}

Answer 1

Seems like you did not correctly set the Replace arguments for the second replacement. You should switch it to this:

txtboxFirstName.Text = MyConfigs.FirstName.Replace("''", "'");

Otherwise every ' in MyConfigs.FirstName will be replaced by ''. That's why you get O''''Brian output.