Advanced Apex Training: Apex Best Practices

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Advanced Apex Training Apex Best Practices
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This article dives into what we, developers at
Kairos Technologies, recently learned as we
attended Apex Best Practices training session
at our Global Delivery Center, Hyderabad. This is
one of many advanced topics the company organized
for all Salesforce developers as part of the
continuous improvement and learning. I took some
time to write this blog to reflect on all the
things I learned (with some of code samples)
 from our Senior Architect and I hope this will
help other developers too. For more details,
please watch this awesome video Winter 16
Release Overview Highlights. Follow along,
as I show you all the guidelines you should
consider when writing code for your next
Salesforce applications.
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Governor Limits
Why governor limits? Force.com is built on a
multi-tenant Architecture. In order to ensure
that Apex code of a single tenant does not
consume significant amount of shared resources on
Force.com platform and to ensure every tenant
gets equal share of the platform
resources. Per-transaction Apex Limits Total
of SOQL Queries 100 (Sync) 200 (Async)Total
of records retrieved 50KTotal of DML
statements 150Total of records processed by
DML 10KTotal heap size 6MB (Sync) 12MB
(Async)Maximum SOQL query runtime before
Salesforce cancels the transaction 120 seconds
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SOQL
Avoid writing non-selective queries except during
batch processing.  Avoid using only negative
operators (!) Use Primary Keys, Foreign Keys,
CreatedDate, LastModifiedDate, External ID or
Unique Fields in query filters. Example for
Batch Processing Mass Delete of Records Bad
Query (When record count exceeds 100K) SELECT
ID, NAME FROM ACCOUNT SELECT ID, NAME FROM
ACCOUNT WHERE NAME ! System.QueryException
Non-selective query against large object type
(more than 100k rows). Consider an indexed filter
or contact salesforce.com about custom indexing
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Good Queries SELECT ID, NAME FROM ACCOUNT LIMIT
5 SELECT ID, NAME FROM ACCOUNT WHERE ID IN IDS 
(Only when ID list is small) SELECT ID, NAME
FROM ACCOUNT WHERE NAME ! AND OWNERID IN
OID What happens if I dont write selective
queries? Salesforce could throw a runtime error
like this System.QueryException Non-selective
query against large object type (more than 100k
rows). Consider an indexed filter or contact
salesforce.com about custom indexing
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Best Practices for Apex Classes

• Apex code must provide proper exception handling.
• When querying large data sets, use a SOQL for
  loop.
• We should not use SOQL or SOSL queries inside
  loops.
• Apex code must provide proper exception handling.
• We should prevent SOQL and SOSL injection attacks
  by using static queries, binding variables or
  escape single quotes method.
• Should use SOSL rather than SOQL where possible.

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• Should not use DML statements inside loops.
• Should not use Async(_at_future) methods inside
  loops.
• Should use Asynchronous Apex(_at_future annotation)
  for logic that does not be executed synchronous.
• Asynchronous Apex should be Bulkified.
• We should not use hardcoded IDs as they may cause
  problem when moved to production.

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Graceful Design of the Code
BAD CODE public class CustomCalendarUtil
public static String getMonth(Integer
month)String varMonth if(month1)varMon
th January else if(month2)varMonth
February....return varMonth This is
functionally correct code but is a maintenance
overhead dueTo many if else statements.
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GOOD CODE public class CustomCalendarUtil
static MapltInteger, Stringgt monthMap new
MapltInteger, Stringgt() private static void
init()monthMap.put(1, January)monthMap.put(2
, February)monthMap.put(3, March) public
String getMonth(Integer month)return
monthMap.get(month)
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Use static methods, avoid storing state
BAD CODE public class CustomCalendarUtil
MapltInteger, Stringgt monthMap new
MapltInteger, Stringgt() private void
init()monthMap.put(1, January)monthMap.put(2
, February)monthMap.put(3, March) public
String getMonth(Integer month)init()return
monthMap.get(month)
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GOOD CODEpublic class CustomCalendarUtil
static MapltInteger, Stringgt monthMap new
MapltInteger, Stringgt() static monthMap.put(1,
January)monthMap.put(2, February)monthMap.
put(3, March) public static String
getMonth(Integer month)return
monthMap.get(month)
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Best Practices for Triggers

• Execute DML statements using collections instead
  of individual records per DML statement.
• Should use collections in SOQL WHERE clauses to
  retrieve all records back in single query.
• Use a consistent naming convention including
  Object name(ex contactTrigger)
• Best to have one Trigger to each object.
• Complex logics should be avoided to simplify
  testing and reuse.
• Bulkify helper classes or methods.
• Trigger should be bulkified and be able to
  process up to 200 records for each call.

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Avoid SOQL inside for loop
BAD CODE trigger GetContacts on Accounts (after
insert, after update) for(Account a
Trigger.new)List c SELECT Id FROM Contact
WHERE AccountId a.Id GOOD CODE trigger
GetContacts on Accounts (after insert, after
update) Set ids Trigger.newMap.keySet()List
c SELECT Id FROM Contact WHERE AccountId in
ids
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Avoid DML operations in for loop
BAD CODE trigger UpdateContacts on Accounts
(after insert, after update) for(Account a
Trigger.new)List cl SELECT Id, LastName FROM
ContactWHERE AccountId a.Id for (Contact c
cl)c.LastName c.LastName.toUpperCase() UPD
ATE cl
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GOOD CODE trigger UpdateContacts on Accounts
(after insert, after update) Set ids
Trigger.newMap.keySet()List cl SELECT Id,
LastName FROM ContactWHERE AccountId in
idsfor(Contact c cl)c.LastName
c.LastName.toUpperCase() UPDATE cl
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SOQL processing for large datasets
BAD CODE List accounts Select Id, name from
Accountfor(Account a accounts)Contact c
new Contact()c.AccountId a.Id....insert
c Salesforce could throw a runtime error like
this- Caused by System.DmlException Insert
failed. First exception on row 0 first
errorCaused by System.LimitException Apex
heap size too large 7522771
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GOOD CODE for(Account account Select Id,
name from Account)//do something Each
iteration returns 200 records. However avoid
performing any DML or SOQL operations inside the
loop. Heap Issue can be avoided. However, this
kind of coding can be avoided altogether
depending uponThe exact requirement
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Best Practices for Testing

• Developers/Testers should always remember to
  write comprehensive tests to cover as many
  scenarios as possible. 75 code coverage is good
  for deployment but not necessarily guarantee a
  bug-free code deliverables. We should target for
  100 code coverage.
• Cover as many lines of code as possible.
• Comments should always be written.
• Should create test data in test classes and
  should not use existing records.
• Avoid using SeeAllDatatrue whenever possible.
• Call methods using both valid and invalid inputs.
• When we write conditional logic, write tests to
  execute each branch of code logic.

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• Test if trigger can handle bulk load.
• Hard coding of IDs should be avoided.
• Test classes should be written along with code
  rather than waiting till the end.
• Should follow naming conventions for test classes
• Ex For updateContact class,create a test class
  updateContactTest instead of TestUpdateContact.

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Test Class
INCOMPLETE _at_isTestpublic class
CustomCalendarUtilTest static testMethod void
testGetMonth()String m CustomCalendarUtil.getM
onth(1)System.assertEquals(January,m) stat
ic testMethod void testGetMonth()String m
CustomCalendarUtil.getMonth(2)System.assertEqual
s(February,m)
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GOOD _at_isTest public class CustomCalendarUtilTes
t  static testMethod void testGetMonthJan()   
      String m CustomCalendarUtil.getMonth(1)  
       System.assertEquals(January, m)    
  static testMethod void testGetMonthApril()   
      String m CustomCalendarUtil.getMonth(4)  
       System.assertEquals(April, m)    
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static testMethod void testGetMonthInvalid()    
     String m CustomCalendarUtil.getMonth(13)  
       System.assertEquals(Invalid Month,
m)       ? ?
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THANK YOU
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