[SalesForce] How to rethrow DmlExceptions as AuraHandledExceptions right

Exception handling in Lightning is a pain. Instead of Lightning showing regular exceptions one has to catch them in code and rethrow them as AuraHandledExceptions as shown below:

try {
    ....
    update records;
}
catch(DmlException ex) {
    throw new AuraHandledException(ex.getMessage());
}

Especially in cases of DmlExceptions that can contain multiple errors (one per record) the output is more than ugly:

My questions:

How can I just show the message of the original first error (the blurry part in my screenshot without all the techie stuff in front of it?
How can I train AuraHandledException to show a nice title not ApexActionError?
Is there any technical reason for requiring to rethrow exceptions for Lightning? And is there a roadmap to make this more convenient.

Best Answer

I just directly rethrow DMLException. They are actually handled properly by the framework. So, my error handling often looks like this:

    try {
        upsert value;
    } catch(DmlException e) {
        throw e;
    } catch(Exception e) {
        throw new AuraHandledException(e.getMessage());
    }

If there is a DMLException, it arrives in Lightning as a structured error object where you can split those errors up into multiple message if you want to.

It would be nice if AuraHandledException had more methods so that we could add structure to custom errors, but I can't find any ability to do that.

Related Solutions

[SalesForce] How to capture those records that was unable to get inserted

You need to use Database.insert() method and get results by using Database.SaveResult.

Also, have a look at the DML parameter optAllOrNone documented here. if you want to roll back the operation in case 1 record fails.

Example code:

List <Contact> contacts = new List <Contact> ();

Contact contact1 = new Contact();
contact1.FirstName = 'TestFirstname';
contact1.LastName = 'TestSurname';
contacts.add(contact1);

Contact contact2 = new Contact();
contact2.FirstName = 'TestFirstname';
contacts.add(contact2);

// Assuming contact2 will fail not having last name populated
List <Database.SaveResult> saveResults = Database.insert(contacts, false);

// Go through each result
for (Database.SaveResult saveResult : saveResults)
{
    if (saveResult.isSuccess() == true)
    {
        // Successfully inserted contact
        // do something 
    }
    else
    {
        // Failed
        for(Database.Error error : saveResult.getErrors())
        {
            System.debug('Something went wrong with the record ID ' + saveResult.getId() + ' : ' + error.getStatusCode() + ' - ' + error.getMessage());
        }
    }
}

[SalesForce] How to write test class for try catch DMLExceptions

It may not be possible to test all error handling scenarios. This is why the code coverage requirement is 75% and not 100%. You must be able to anticipate errors that are not possible from your own code but might be possible after an administrator adds a validation rule, etc.

I've always said that, based on my observations, writing test methods follows the Pareto principle. In other words, 20% of the code you could write for test methods should cover 80% of your code, and the remaining 80% of the code you would write for test methods would be needed to cover the remaining 20%.

Covering 100% is often impossible, and most organizations recognize this. Even covering 90% requires probably close to at least 2 times more than required to cover 80%. This is because your main execution line should be around 80%, while unexpected exceptions should generally be in the remaining 20%.

That said, you should focus on setting a goal of 85% or 90%. If your code is less than 10 lines long, then that class or trigger will probably be less than 80% with proper error handling-- don't worry about it, because it's likely that you'd either have to write test code in your class or trigger (e.g. if(Test.isRunningTest() && TestUtil.causeFailure) { throw new Exception('Test Exception'); }), which is a bad practice, or you'd have to not write any error handling code, which is also impractical in production code.

Best Answer

Related Solutions

[SalesForce] How to capture those records that was unable to get inserted

[SalesForce] How to write test class for try catch DMLExceptions

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