Handling nulls on checkbox fields in Apex

Question

I have a custom object with a couple of checkbox fields. Those fields have a Default Value of "Unchecked".

How should those fields behave when assigned a null value in Apex?

Simplified example code:

Boolean nullBoolean;
System.assertEquals(null, nullBoolean, 'Expected to be null');

RepType__c rt = new RepType__c();
// Assign the checkbox fields from the variable
rt.IsOrderManagerRepType__c = nullBoolean;
rt.IsAccountManagerRepType__c = nullBoolean;

// Expected to be null, but comes back as false (the default value?)
System.debug('Direct field value: ' + rt.IsAccountManagerRepType__c); 
//System.assertEquals(null, rt.IsAccountManagerRepType__c, 'This assertion will currently fail');

// Shows that the checkbox fields are null
System.debug(rt);
// Confirms checkbox fields are null, not false
System.debug(JSON.serializePretty(rt)); 

insert rt;

Basic Debug output:

Direct field value: false
RepType__c:{IsOrderManagerRepType__c=null, IsAccountManagerRepType__c=null}

JSON debug output:

{ "attributes" : { "type" : "RepType__c" }, "IsOrderManagerRepType__c" : null, "IsAccountManagerRepType__c" : null }

Exception from insert:

System.DmlException: Insert failed. First exception on row 0; first error: INVALID_TYPE_ON_FIELD_IN_RECORD, IsAccountManagerRepType: value not of required type: : [IsAccountManagerRepType__c]

Note how any direct code access to the checkbox field in Apex gives the value as being false. So if I check it in code it looks fine to insert. However, the debug of the entire object and attempts to use it in DML show the null value.

Answer 1

Answer from support for Case #14025277

R&D has confirmed that this is a documentation issue. The documentation will be updated to clarify this behavior (please see below).

"The expression accessing a Boolean type field on an sObject with simple dot notation is evaluated to true only if the field value is non-null and true. Otherwise it is evaluated to false."

As you may already know - To check the checkbox value when using null, please use sObj.get('fieldname').

Answer 2

I think all of this comes from a fact that Boolean in Apex can have 3 values while Checkbox in database can have only two. Some of the outputs are really questionable.

I would propose to use fact that JSON has correct value to check where we actually are:

 rt.IsOrderManagerRepType__c = nullBoolean;
 system.debug(rt.IsOrderManagerRepType__c!=null);          //true
 system.debug(rt.get('IsOrderManagerRepType__c')!=null);   //false