Apex Video Tutorial: Combine SOQL & Apex

Preface: This video is part 3 of the Official #Apex4Admins series presented by Salesforce and I!

Combine your knowledge from part 1 and 2 to write an epic deduping trigger!

1. Lists and dot notation!
2. Combining SOQL and Apex using bind varibles!
3. How to write good test classes!
4. Write a deduping trigger!

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Lists

List<Food__c> dollarMenu = [SELECT Id, Name FROM Food__c 
                             WHERE Price__c = 1];
Food__c firstItem  = dollarMenu[0]; // McChicken
Food__c secondItem = dollarMenu[1]; // Sausage Biscuit
Food__c thirdItem  = dollarMenu[2]; // McDouble
Food__c fourthItem = dollarMenu[3]; // Hash Browns

List<String> buddies = new List<String>();
buddies.add('Ronald McDonald');
buddies.add('Hamburglar');
buddies.add('Mayor McCheese');
buddies.add('Officer Big Mac');

Dot Notation

// Use Case #1: Access fields
String sandwichName = dollarMenu[0].Name;

// Use Case #2: Traverse relationships
String me = dollarMenu[0].Eaten_By__r.Name;

// Use Case #3: Access methods!
dollarMenu.remove(2); // Farewell McDouble
// Every data type has methods!
Food__c newItem = new Food__c();
newItem.Name = 'bbq Ranch Burger'.capitalize();
dollarMenu.add(newItem);

Bind Variables

// Use variables inside your SOQL queries!
String bestMcDonaldsItem = 'Chocolate Dipped Ice Cream Cone';
List<Food__c> bestItems = [SELECT Id, Name FROM Food__c
                            WHERE Name = :bestMcDonaldsItem];
 
// You can use Lists as Bind Variables too
List<String> dietFoodNames = new List>();
dietFoodNames.add('Apple Slices');
dietFoodNames.add('Side Salad');
dietFoodNames.add('Fruit & Yogurt Parfait');
List<Food__c> bannedFoods = [SELECT Id, Calories__c FROM Food__c
                              WHERE Name IN :dietFoodNames];

Test Class Principle #1: Create Records from Scratch

Contact dupeContact  = new Contact();
dupeContact.LastName = 'Spiderman';
dupeContact.Email    = 'spiderman@gmail.com';
insert dupeContact;            

Lead dupeLead = new Lead();
dupeLead.FirstName = 'Peter';
dupeLead.LastName  = 'Parker';
dupeLead.Company   = 'Daily Bugle';
dupeLead.Email     = 'spiderman@gmail.com';
insert dupeLead;

Test Class Principle #2: Use System.assertEquals()

// Example: This obviously comes out to true
System.assertEquals(true, bestWebinarEver);
// Example: This will give you an error and fail your test class!
System.assertEquals('Tom Brady', bestActiveQuarterback);
// Query the post-trigger values and assert assumptions
dupeLead = [SELECT Id, Dupe_Contact__c FROM Lead
             WHERE Email = :dupeLead.Email LIMIT 1];
System.assertEquals(dupeContact.Id, dupeLead.Dupe_Contact__c);

Test Class Principle #3: Test Negative Scenarios Too!

// Create a lead that SHOULDN'T have a dupe
Lead uniqueLead = new Lead();
uniqueLead.LastName = 'Xavier';
uniqueLead.Company  = 'X-Men';
uniqueLead.Email    = 'theprofessor@xmen.com';
insert uniqueLead;

// Assert that a dupe isn't identified on the lead        
uniqueLead = [SELECT Id, Dupe_Contact__c FROM Lead 
               WHERE Email = :uniqueLead.Email LIMIT 1];
System.assertEquals(null, uniqueLead.Dupe_Contact__c);

Test Class Principle #4: Test in Bulk!

// Add 200 new Contacts to a list
List<Contact> dupeContacts = new List<Contact>();
for (Integer i = 0; i < 200; i++) {
    Contact c   = new Contact();
    c.FirstName = 'David';
    c.LastName  = String.valueOf(i);
    c.Email     = 'contact' + c.LastName + '@gmail.com';
    dupeContacts.add(c);
}

// Insert all 200 contacts at the same time
insert dupeContacts;

Deduping Trigger

// Populate a Contact Lookup field if there's a dupe!
trigger DetectDupes on Lead (before insert, before update) {
    for (Lead l : Trigger.new) {
        if (l.Email != null) {
            String leadEmail = l.Email;
            List<Contact> dupeContacts = [SELECT Id FROM Contact
                                          WHERE Email = :l.Email];
            if (dupeContacts.size() > 0) {
                l.Dupe_Contact__c = dupeContacts[0].Id;
            } else {
                l.Dupe_Contact__c = null;
            }
        } else {
            l.Dupe_Contact__c = null;
        }
    }
}

Deduping Trigger Test Class

@isTest
public class TestDeduper {
  static testMethod void testDupes() {
    // Principle #1: Create records from scratch!
    Contact dupeContact  = new Contact();
    dupeContact.LastName = 'Spiderman';
    dupeContact.Email    = 'spiderman@gmail.com';
    insert dupeContact;            

    Lead dupeLead = new Lead();
    dupeLead.FirstName = 'Peter';
    dupeLead.LastName  = 'Parker';
    dupeLead.Company   = 'Daily Bugle';
    dupeLead.Email     = 'spiderman@gmail.com';
    insert dupeLead;
        
    // Principle #2: Use System.assertEquals()
    dupeLead = [SELECT Id, Dupe_Contact__c FROM Lead
                 WHERE Email = :dupeLead.Email LIMIT 1];
    System.assertEquals(dupeContact.Id, dupeLead.Dupe_Contact__c);
        
    // Principle #3: Test things that shouldn't work!
    Lead uniqueLead = new Lead();
    uniqueLead.LastName = 'Xavier';
    uniqueLead.Company  = 'X-Men';
    uniqueLead.Email    = 'theprofessor@xmen.com';
    insert uniqueLead;
        
    uniqueLead = [SELECT Id, Dupe_Contact__c FROM Lead 
                   WHERE Email = :uniqueLead.Email LIMIT 1];
    System.assertEquals(null, uniqueLead.Dupe_Contact__c);
  }
}