Save error: Initial term of field expression must be a concrete SObject: String

Question

I've authored this trigger but around line 8, where the if(string.valueof) statement begins, I seem to be stuck in that I get the message "Initial term of field expression must be a concrete object."

I am authoring a trigger that creates a task each time an email is sent and assigns a WhoId based on the email address of the recipient. Are there any steps I should take?

Hope it helps,

trigger EmailToTask on EmailMessage (after insert) {
    list<Task> lstTask= new list<Task>();
    map<String,Id> mapEmail = new map<String,Id>();
    map<String,Id> mapWorkEmail = new map<String,Id>();
    map<String,Id> mapHomeEmail = new map<String,Id>(); 
    for(Contact con: [SELECT Id,Email,npe01__WorkEmail__c,npe01__HomeEmail__c FROM Contact]){
        if(string.valueOf(con.Email).isNotBlank)
            mapEmail.put(con.Email,con.Id);
        if(string.valueOf(con.npe01__WorkEmail__c).isNotBlank)
            mapWorkEmail.put(con.npe01__WorkEmail__c,con.Id);
        if(string.valueOf(con.npe01__HomeEmail__c).isNotBlank)
            mapHomeEmail.put(con.npe01__HomeEmail__c,con.Id);
    }

    for (EmailMessage e : Trigger.new) {
       if (e.RelatedToId != NULL 
       && (mapEmail <> NULL && !mapEmail.isEmpty()
           || mapWorkEmail <> NULL && !mapWorkEmail.isEmpty()
           || mapHomeEmail <> NULL && !mapHomeEmail.isEmpty())
           ) {
           Task t =  new Task();
           t.ActivityDate  = date.today();
           t.Description   = e.TextBody;
           t.Move_Type__c  = 'Personal Note/Email from Donor';
           t.Priority      = 'Normal';
           t.Status        = 'Completed';
           t.Subject       = e.Subject;
           t.WhatId        = e.RelatedToId;
           if(mapEmail.containsKey(e.ToAddress)){
                t.WhoId =mapEmail.get(e.ToAddress);
           }
           else if(mapWorkEmail.containsKey(e.ToAddress )){
                t.WhoId =mapWorkEmail.get(e.ToAddress);
           }
           else if(mapHomeEmail.containsKey(e.ToAddress )){
                t.WhoId =mapHomeEmail.get(e.ToAddress);
           }
           lstTask.add(t);
        }
    }
    if(lstTask <> NULL && !lstTask.isEmpty()){
        insert lstTask;
    }
}

Answer 1

It is easy enough to reproduce this error message with a similar anonymous script:

Incorrect

Contact record = [SELECT Email FROM Contact LIMIT 1];
Boolean b = String.valueOf(record.Email).isNotBlank;

You can't check for blank strings like that; isNotBlank is a method which you must call, and it is static as well.

Correct

Contact record = [SELECT Email FROM Contact LIMIT 1];
Boolean b = String.isNotBlank(record.Email);