The document discusses the differences between coders and software developers, specifically in the context of defensive programming practices within the Salesforce platform, emphasizing the software application life-cycle and maintenance. It highlights the importance of avoiding vulnerabilities in future calls and custom settings while also addressing concurrency errors during record updates. Additionally, the document touches on continuous integration processes for Salesforce, encouraging the use of tools like Jenkins and providing links for further resources.

1. Defensive Apex Programming
Dan Appleman
CTO – Full Circle Insights, Author of Advanced Apex Programming
dan@fullcircleinsights.com
@danappleman

2. What is the difference between a coder (“code monkey”)
and a software developer?
Say what???

3. The Software Application Life-Cycle
Requirements
Design
Code
Test/QA/Doc
Maintenance

4. The Software Application Life-Cycle - Traditional
Requirements
Design
Code
Test/QA/Doc
Maintenance
• Bug fixes
• New OS version/browser
• Platform changes
• Regression testing of
changes by developers
• Critical features

5. The Software Application Life-Cycle – Salesforce Platform
Requirements
Design
Code
Test/QA/Doc
Maintenance
• Bug fixes
• Platform updates (3x per year)
• Regression testing of changes
by developers
• Critical features
• Metadata changes that
change the behavior of the
code.

6. Traditional Applications
Platform
Your App
Platform
Apex
Other declarative
metadata changes
Apex Applications

7. Defensive Apex Programming

8. Making a Future Call – The Wrong Way
public void CallFuture1()
{
vulnerableFutureCall();
}
@future
public static void vulnerableFutureCall()
{
// Do something here
}

9. Making a Future Call – The Wrong Way
public void CallFuture1()
{
vulnerableFutureCall();
}
@future
public static void vulnerableFutureCall()
{
// Do something here
}
• Other app calls this in a future context?
• Batch calls this?
• Other code makes future calls and we hit limit?
• An error occurs during the future call?
(you’ll never know it)

10. Defensive Future Calls
public void CallFuture2()
{
if(System.isFuture() || system.isBatch()) defensiveFutureCallSync();
else {
if(Limits.getFutureCalls()< Limits.getLimitFutureCalls())
defensiveFutureCallAsync();
else { // ????
}
}
}
@future
public static void defensiveFutureCallAsync()
{
defensiveFutureCallSync();
}
public static void defensiveFutureCallSync()
{
// Do something here
}
• Backs up to sync pattern (if applicable)
• Alternatives include try/catch & logging errors
instead
• Reliable async is a much bigger topic...

11. Using a Custom Setting – The Wrong Way
Boolean enabled = ConfigSettings__c.getInstance('default').Application_Enabled__c;
Guaranteed null reference exception on:
• Uninitialized orgs/sandboxes (metadata push)
• SeeAllData false tests on methods that don’t initialize setting
• SeeAllData false tests on managed package tests that can’t initialize
setting.

12. Defensive Custom Settings
private static ConfigSettings__c testConfig;
public static ConfigSettings__c getConfig()
{
if(Test.isRunningTest() && testConfig!=null) return testConfig;
ConfigSettings__c result = ConfigSettings__c.getInstance('default');
if(result==null)
{
result = new ConfigSettings__c(name='default', Application_Enabled__c= false);
}
if(Test.isRunningTest()) testConfig = result;
return result;
}
Then...
Boolean enabled = ConfigurationClass.getConfig().Application_Enabled__c;
• Can’t return null
• Protects from DML
errors on parallel tests
• Simplifies test setup

13. Detecting a Field Change
Demo

14. Updating Records – Watch For Concurrency Errors
update listOfRecords;
or
List<Database.SaveResult> dmlResults =
Database.Update(listOfRecords, false);
for(Integer x = 0; x< ops.size(); x++)
{
Database.SaveResult sr = dmlResults[x];
if(!sr.isSuccess())
{
for(Database.Error err: sr.getErrors())
{
if(err.getStatusCode() == StatusCode.UNABLE_TO_LOCK_ROW)
{
// Concurrency error
}
}
}
}
Variations include
• try/catch blocks
• setSavePoint/rollBack
• all or nothing
• Logging vs retry

15. You can’t defend against every metadata change!

16. Continuous Integration – In Traditional Software Development
Software
repository
Jenkins Build
Developer
Developer
Developer

17. Continuous Integration – In Salesforce Too!
OrgJenkins Build
Developer
Developer
Developer

18. Continuous Integration – In Salesforce Too!!!!!!!!!
Org
Developer
Developer
Developer
CI app

19. Continuous Integration – In Salesforce Too!!!!!!!!!
Org
Developer
Developer
Developer
CI app
Managed PackageCI App

20. Native TestTracker App
http://AdvancedApex.com/TestTracker
Free private managed package
Open Source

21. Questions?
Test Tracker tool
http://AdvancedApex.com/testtracker
For more information, see chapter the new chapter
12 “Maintaining Apex” of the just released third
edition.
Also check out:
Career Strategies and Opportunities for Salesforce
Platform Developers on pluralsight.com