validation step by step - asp.net

Question

I have an aspx page with three textbox controls, and i want to do validation for all.
i want to show the error message in a sequence,
for example if i left all three text boxes empty and click on submit button,
first it will show error message for first text box and then when i fill the first textbox and click again save then it shows the error message for the second textbox and so on.
that means i only want to show one error message at a time after clicking the submit button.
can you people suggest me the way.

Answer 1

You could do it though checking on submission of the form and posting back to a literal with error messages. Postback validation is better than just relying on javascript in any case.
So, depending on the level of checks you want to employ, you could do something like:
protected void btnSubmit_Click(object sender, eventArgs e)
{
if(String.IsNullOrEmpty(txtBox1.Text))
{
ltError.Text = "Sorry, error message for box1";
return;
}
}
Obviously you'd work in more checks and after passing stage1 you'd move on to stage 2. Not great from a user experience but would work.

Answer 2

you can return a function value like this
public string CheckValidation()
{
if (txtFirstName.Text.Trim().Equals(string.Empty))
return "Please enter firstname";
if (txtLastName.Text.Trim().Equals(string.Empty))
return "Please enter lastname";
}
and so on as per your validation fields.
Hope this helps you

Answer 3

Can you use the AJAX control toolkit? The VaidatorCallout controls behave this way and you get a nice little balloon indicating where the error is.
ASP.NET Validator Callout

Answer 4

I'd recommend an <asp:CustomValidator> control for each textbox. You can use something like the following for the custom validation routines:
var textBox1IsValid = function textBox1IsValid(sender, args) {
var tb = document.getElementById('TextBox1'),
resultOfValidation = false;
//do validation, modifying resultOfValidation as needed.
arg.IsValid = resultOfValidation;
return resultOfValidation;
},
textBox2IsValid = function textBox2IsValid(sender, args) {
var tb = document.getElementById('TextBox2'),
resultOfValidation = false;
//do validation, modifying resultOfValidation as needed.
//return either the validity of TextBox2
//or (if TextBox1 is not valid) return true so the
//validator for TextBox2 doesn't fire.
arg.IsValid = resultOfValidation || !textBox1IsValid(sender, args);
return resultOfValidation;
},
textBox3IsValid = function textBox3IsValid(sender, args) {
var tb = document.getElementById('TextBox3'),
resultOfValidation = false;
//do validation, modifying resultOfValidation as needed.
//return either the validity of TextBox3
//or (if either TextBox1 or TextBox2 is not valid) return
//true so the validator for TextBox3 doesn't fire.
arg.IsValid = resultOfValidation || !textBox1IsValid(sender, args) || !textBox2IsValid(sender, args);
return resultOfValidation;
};
The advantage of this approach is that TextBox2 and TextBox3 will return as valid if their contents are valid or if TextBox1 is not valid. This will fire only one validator at a time, until all fields are valid. It's also a little more flexible as your custom validation routine can check for:
required field
pattern matching
value comparison
or any other validation that you need, all wrapped up into one function.
The downside is that you'll also need to duplicate the validation logic server-side.