Check for error messages on vf pages

Question

Can we check if there are any error messages on a Visualforce Page?

My scenario is to redirect to a record after a record is inserted on button click. I have an oncomplete attribute on a commanbutton that redirects to specific record.

But if there are any error message in process of insertion, it shouldn't redirect and error message should be displayed on page.

My plan was to check for any error messages on Visualforce Page and call the redirect in oncomplete if error messages doesn't exist.

<apex:commandButton id="btnSubmit" value="Submit" action="{!submit}" oncomplete="redirect()"/>

Please let me know if this is possible or any other solutions that suits my situation.

Answer 1

You are looking for ApexPages.hasMessages (documentation):

if (ApexPages.hasMessages()) return null;
return intendedReference

If you want to use it in Javascript, you can expose a property like so:

public Boolean hasError { get { return ApexPages.hasMessages(); } }

Then in your script you can check it like:

if ({!NOT(hasError)}) // do your redirect 

Answer 2

The more common pattern, given that you are calling a server-side controller method anyway, is to make the decision in Apex:

public PageReference submit() {
    ...
    return return ApexPages.getMessages().size() == 0 ? Page.NextPageName : null;
}

where returning null leaves you on the current page. You then don't need the oncomplete logic in the Visualforce.

Answer 3

I ran into the same problem implementing a js method which prevented multiple submissions by deactivating the submit buttons. I wanted this method to deactivate the submit buttons if the data submitted had no VF errors, but not if it did. Like others, I tried testing apexPages.hasMessages() but found that it always returned true, even when a user had corrected their data.

I eventually ended up giving users one chance to correct their data, and moving on or erroring out after that.

I created a global js variable: let AlreadySubmitted = false;

Then I used it in a js method I called onClick:

    function preventMultipleSubmissions(){
        elem = document.getElementById('apexErrorMessagesSection');
        if (elem.innerText.length==0 || AlreadySubmitted==true) {
            document.getElementById('SubmitAndNextButton').disabled = true;
            document.getElementById('SubmitAndExitButton').disabled = true;
        } else {
            elem.scrollIntoView(true);
        }
            AlreadySubmitted=true;
    }