Fields not rendered still save

Question

I'm using custom_object on the Visualforce Page and showing the fields based on the user selection on the picklist, even though I hide the fields the value is still saving to the object, how do I not save the fields in the object which is not rendered/hide?

To give you an example here is how I'm not rendering the field based on the condition:

<apex:inputField value="{!Employee__c.WeekDay__c}" rendered="{!isTransSelected==true}"  />  

I'm using the following Save action:

public PageReference Save()
{
    try
    {
        system.debug('updating: ' + employeeObj);
        update employeeObj;
    }
    catch (exception e){           
        ApexPages.addMessages(e);
    }
    return null;           
}

Or should I explicitly defined what fields needs to be updated?

Answer 1

If you want to update specific fields, one option is to create a new copy of the SObject that only contains that data.

Employee__c record = new Employee__c();
for (SObjectField field : /*yourCollection*/)
{
    if (/*shouldSaveField*/)
    record.put(field, controllerRecord.get(field));
}
// try/catch