Custom Validation example

[rotten.tech]

Hi Gurus

I am new to SmartGWT and so far I am really enjoying it. I am trying to write a custom validator but couldnt get it working.

Background of my application:
I have a form to collect user information. This form is linked to a Data Source for persisting data. I am using Grails as back-end and using RestDataSource to write and retrieve data in my application.

What I want:
In this form, there is a "ID" field which should be unique. This uniqueness should be checked as soon as the form text field looses focus. For this in Grails I have created a URL which will check "success" or "failure" after checking for the "ID" in the DB.

My approach till now:
Coming from a JSF background, I was planning on creating a Custom Validator and attach it to the field so that it gets validated onblur.
However when I started, I could not get the exact things I would need to get it working.

Can someone please point me in the correct direction as to how this can be done? Any help appreciated! and thanks in advance.

[Primm]

Some sample code from you would be helpful, but here is a sample on how to do this:

final TextItem item = new TextItem("id", "ID");
CustomValidator validator = new CustomValidator() {
    @Override
    protected boolean condition(Object value) {
        // Put your validation check here
        return callToService(value);
    }
};

item.setValidators(validator);

item.addBlurHandler(new BlurHandler() {
    @Override
    public void onBlur(BlurEvent event) {
        item.validate();
    }
});

Hope this was helpful.

[rotten.tech]

Thanks for the example.
However I am kinda stuck on how to call a REST api for the validation. For example my URL is "/person/check" which takes in a user ID and returns a 0 or 1 depending on the check.

Is there a way to do it directly from the code? Do I need to use a datasource? Since I already have a datasource for the form, is it possible to link a field to 2 datasources?

Thanks a lot in advance.

[ferranmc]

I think you can't make a call to your server (which is asynchronous) inside the "boolean condition(Object value)" method since it is synchronous.
I don't know how to do this anynchronous validation.

[rotten.tech]

Oh! I see. So any way of achieving it?

[michalg]

This may help.
MichalG

[ferranmc]

I would do something like this:

// SIMPLIFIED CODE

item.addBlurHandler(new BlurHandler() {
    @Override
    public void onBlur(BlurEvent event) {
        service.checkValue(item.getValue(), new Callback() {
            public void onSuccess(valueCheck check) {
                if( ! check.isOk() ) {
                    markItemAsWrong(item);
                }
            }
        };
    }
});

I don't know how to mark an item as wrong (that's what validate() does internally).

Anyway, this solution is a bit complicated because when the user clicks submit on the form you must also call service.checkValue() and wait for the callback before you really submit the form.

I would like to know a better solution.

[ferranmc]

This may help.
MichalG

Thanks! It seems that 3.0 has added async validation.

[rotten.tech]

Thanks all for your support.
Tried a few things and now I think I'll go with the server validation as of now. So on submit i am checking on the grails side if the user id is unique and if not then returning a json mentioned here: http://www.smartclient.com/smartgwt/showcase/#form_validation_server_json

I am digging into it further. Will update this ticket if I find a better solution.