Invalid Foreign Key Relationship when referring to custom object text field

Question

Hopefully this is a simple one, but I'm pretty stumped. Basically, I'm editing a text field of a custom object. However, it seems I get a Invalid Foreign Key Relationship error when I try and check whether the field is null:

Here's the code that throws the exception:

for(Account a: listOfAccounts{
    for(object__c o: listOfObjects){
        if(!o.Name.isBlank()){
             o.Name.replace(a.textField__c, '');
        }
    }
}

Not sure why, since this works:

for(Account a: listOfAccounts{
    for(object__c o: listOfObjects){     
        o.Name.replace(a.textField__c, '');
    }
}

However, this code throws a null pointer exception if o.Name is null

Answer 1

isBlank is a static method of the String class. You want:

if(!String.isBlank(o.Name)){
         o.Name.replace(a.textField__c, '');
}

Answer 2

It's the way you have the 'Is Not Blank' set up

!o.Name.isBlank()

Should be

NOT(ISBLANK(o.Name))

Answer 3

Looks like the answer is !String.isEmpty(o.Name) (as it states in the documentation :/)