Turning a concept into code – begin writing an advanced trigger!

Preface: this post is part of the Write Your First Advanced Trigger series.

Imagine for a moment that you’re enjoying the perfect meal in paradise:

Ah… what better place to contemplate the intricacies of Salesforce?

Suddenly, it hits you like a tidal wave. The perfect trigger. This will surely solve that one problem that one person brought up in that meeting a few weeks ago! WAITER!! NAPKIN AND A PEN, PRONTO!!

Let’s begin writing pseudo-code for this chapter’s trigger! (Scroll down for the full trigger diagram)

Node #1: Begin Trigger on Accounts!

trigger ShareTerr on Account (after insert, before update) { .. }

Background learning: When to use before vs after triggers!

Node #2: Is the Account being inserted?

if (Trigger.isInsert) {
  // Move on to Node #9
} else if (Trigger.isUpdate) {
  // Move on to Node #3
}

Background learning: Trigger Context variables.

Node #4: Has the Zip Code changed?

String oldZip = Trigger.oldMap.get(acc.Id).BillingPostalCode;
String newZip = acc.BillingPostalCode;
if (newZip != oldZip) { ... }

Background learning: Comparing old and new values in a trigger!

Node #7: Do a SOQL query for AccountShare records on the Account

List<AccountShare> shares = [SELECT Id FROM AccountShare 
                              WHERE AccountId = :acc.Id
                                AND RowCause = 'Manual'];

Background learning #1: AccountShare object
Background learning #2: Using Apex variables in a SOQL query

Node #8: Delete AccountShare records

delete shares;

Background learning: Creating, updating, and deleting records

Node #10: Do a SOQL query to find a Territory based on Zip Code

Territory__c terr = [SELECT Id FROM Territory__c 
                      WHERE Zip_Code__c = :acc.BillingPostalCode];

Background learning: Using Apex variables in a SOQL query

Node #11: Is there a matching Territory?

if (terr != null) {
  // Move on to Node #13
} else {
  // Move on to Node #12
}

Background learning: IF statements

Node #13: Do a SOQL query for all Territory Members on the Territory

Territory__c terr = [SELECT Id, 
                    (SELECT Id, User__c FROM Territory_Members__r)
                       FROM Territory__c
                      WHERE Zip_Code__c = :acc.BillingPostalCode];

Since we already do a query on the Territory__c object for Node #10, we might as well query for the related Territory Members in the same query too to reduce our overall number of SOQL queries!

Background learning #1: How to write a cross-object SOQL query (“downwards”)
Background learning #2: Why and how to Bulkify your Code

Node #14: Create an AccountShare record for each Territory Member

List<AccountShare> newShares = new List<AccountShare>();
for (Territory_Member__c tm : terr.Territory_Members__r) {
  AccountShare aShare           = new AccountShare();
  aShare.AccountId              = acc.Id;
  aShare.UserOrGroupId          = tm.User__c;
  aShare.AccountAccessLevel     = 'Edit';
  aShare.OpportunityAccessLevel = 'Edit';
  newShares.add(aShare);
}
insert newShares;

Notice the syntax used to iterate through each Territory Member associated with the Territory! It’s the same identifier used when writing a downwards SOQL query.

Background learning #1: Loops – FOR and FOREACH loops
Background learning #2: AccountShare object

Diagram of this chapter’s trigger:

Whew! Great pseudo-code brainstorming session!

But our code isn’t done, we haven’t even bulkified it yet!

Let’s hurry up and finish this meal so we can rush back to the hotel and write our full trigger!

Next post: Example: How to write an Advanced Trigger!