SFDC Introduction to Apex

Force.com Apex Basics
Sujit Kumar
Zenolocity LLC © 2012 - 2024

Apex Overview
• Basics – comparison to Java
• Types, Casting, Rounding, Date, Time, DateTime
• Arrays and Collections
• Exceptions
• Future Methods
• Database Integration – SOQL, SOSL, DML, Database
Methods, Triggers, Security.
• OO – Classes, Interfaces, Inheritance, Polymorphism
• Debug Logs – Categories & Levels, Filters
• Unit Testing

Apex Language Basics
• OO, Stored Procedure like language, runs on
Force.com platform only.
• Tightly integrated with Force.com DB.
• Used to code user interfaces and triggers.
• Apex programs run in a multi-tenant
environment => subject to governor limits.
• Integrated testing – code coverage atleast 75%
to be deployed to prod.

Declarative Patterns
• Simplicity & Speed
• Data Model – Objects, Fields & Relationships
• Business Logic – Workflow, Validation Rules &
Assignment Rules
• User Interface – Applications, Tabs, Page
Layouts & Record Types

Programmatic Patterns via Apex
• Control & Flexibility
• Data Model – Metadata Web Services API.
• Business Logic – VF Controllers, Apex, Web
Services API.
• User Interface – Visualforce Pages, Web
Controls.

Overview (contd…)
• Platform automatically upgraded. Force.com will
run all your tests before upgrade.
• No offline runtime environment for Apex
programs, must be deployed to Force.com for
execution.
• Only supported language on Force.com platform.
• Force.com DB is the only DB integrated into Apex.
• 2 choices for development – Web Based App
Builder Tool and Force.com IDE (standalone or
eclipse plug-in).

Apex .vs. Java
• Very similar – strongly typed, pass by
reference, Object Oriented, etc.
• Differences include:
• Apex runs in a multi-tenant environment
• Subject to limits
• Case-insensitive
• Transactional behavior is out of the box.

Apex Types
• Strongly Typed language, similar to Java.
• String (contains Unicode characters), Boolean,
DateTime, Date, Time, Integer (signed 32-bit),
Long (signed 64-bit), Decimal (signed m.n,
total of 19 characters), Double (signed 64-bit
with decimal), Blob, ID, Object.
• ID stores the unique ID of DB records. Total of
18 characters. Values checked at compile time
& run time. Can throw StringException.

sObject Data Type
• Represents a row in the Force.com database.
• Initialized to null by default. Null data type
contains the null constant.
• Declared using the API name for the object.
• Can be instantiated using name/value pairs.
• sObject reference field key can be used to
insert, update or upsert to resolve foreign keys
by external ID.

Casting
• Implicit conversion for Numeric Types.
• Integer => Long => Double => Decimal
• ID and String are interchangeable, can throw
StringException.
• Convert from string to numeric types using
valueOf method. Can throw TypeException.
Examples: Integer.valueOf(‘123’),
Decimal.valueOf(‘123.34’)

Rounding
• By default, the rounding mode is HALF_EVEN,
which rounds to the nearest neighbor, or to
the even neighbor if equidistant.
• Examples: 0.5 will round to 0, 0.6 will round to
1, 1.5 will round to 2.

Date, DateTime, Time
• Use valueOf method on Date and DateTime.
• No valueOf method on Time type.
• For Date, default format is YYYY-MM-DD
• For Datetime: YYYY-MM-DD HH:MM:SS
• DateTime has a format method that follows
the SimpleDateFormat of java.

Arrays and Collections
• Collections: List, Set and Map.
• Collections support 4 methods: clear, clone,
isEmpty and size.
• Multi-dimensional arrays are NOT supported.
• 2-D list object by nesting a list within a list is
possible.
• Arrays and Lists are interchangeable. (See
Speaker Notes)

Collections
• Not more than 1000 elements in a collection.
• A Collection can contain another collection - not more
than 5 levels deep.
• Cannot add/remove while iterating over a collection.
• Set - unordered collection of unique primitives.
• List - ordered collection of primitives, sObjects,
collections or Apex objects based on indices.
• Map - collection of unique primitive keys, values can be
primitives, sObjects, collections or Apex objects.

Exceptions
• Similar to Java using try, catch and finally.
• Common system exceptions:
DmlException (issues with changes to the DB),
NullPointerException,
QueryException (issues with DB queries), and
TypeException (issues converting data types).
• System Exception during recursion – max stack
depth is not documented.

Apex Asynchronous Execution
• Asynchronous mode of execution using Future
methods.
• Future methods tagged with @future.
• Used to perform expensive tasks that are not
time-critical.
• A regular synchronous method can begin some
work and invoke a future method to finish it.
• The future method starts fresh with respect to
governor limits (3MB code, 200k l.o.c., 50k
records retrieved from SOQL).

Limitations of Future Methods
• Cannot invoke more than 10 future methods in a single
scope of execution.
• FMs cannot call other FMs.
• Signature is always static and void.
• Parameters have to primitive types or collections of
primitive types.
• Cannot test FMs like normal methods (NMs).
• Max of 200 FMs per user within a 24-hour window.
• How to test FMs? Invoke a NM as the only line in a FM and
write test cases for the NM that is invoked in the FM.
• Batch Apex is more powerful than FMs.

Database Integration in Apex
• Database integrated into the language & runtime.
• No ORM tools, no DB connection pools.
• Apex code aware of all objects, fields and security
rules.
• All DB Objects (standard and custom) are
implicitly imported as Classes in Apex.
• Use SOQL to retrieve.
• Built-in DML to do CRUD operations.

DB Integration (contd…)
• Can write apex code in triggers.
• Apex code runs in a privileged mode, granting full
access to all data. Can be configured to run as a
certain user.
• References to database objects and fields are
verified at compile time.
• Database relationships are also exposed in Apex.
The __r syntax refers to a relationship field, a
field that contains a reference to another object
or list of objects.

SOQL Basics
• Centered on a single DB object, specifying 1 or more fields
to retrieve from it.
• Case-insensitive.
• The result of a SOQL query can be a simple list of records
containing rows and columns or hierarchies of records
containing data from multiple, related objects.
• Child-to-Parent SOQL – simple list of child objects. Where
fields from a parent object are included in the query, they
are available as nested variables in Apex code.
• Parent-to-Child SOQL – simple list of parent objects. Each
record of the parent object includes a nested List of child
objects.

SOQL For Loop
• Allows it to run when the Project object contains up to
50,000 records for this year without consuming 50,000
records worth of heap space at one time.
Decimal totalHours = 0;
for (Proj__c project : [ SELECT Total_Billable_Hours_Invoiced__c
FROM Proj__c
WHERE Start_Date__c = THIS_YEAR ]) {
totalHours += project.Total_Billable_Hours_Invoiced__c;
}
• Above code is still inefficient & run out of governor limits.
• Change the type of variable in the For loop to a list of
Project records, Force.com provides up to 200 records per
loop iteration. This allows you to modify a whole list of
records in a single operation.

DML
• 5 Statements supported – up to 200 records of he
same type.
1. Insert
2. Update (records identified by Id field)
3. Upsert: try update first, otherwise insert.
4. Delete: moves records to Recycle Bin.
5. Undelete: restores records from Recycle Bin.
• Can use DML statements (all or nothing when
there is error) or database methods (allow partial
success).

Triggers – when to use them.
• A validation rule is required that is too complex to
define on the database object using formula
expressions.
• Two objects must be kept synchronized. When a
record in one object is updated, a trigger updates
the corresponding record in the other.
• Records of an object must be augmented with
values from another object, a complex calculation
or external data via a Web service call.

Triggers
• Work on insert, update, delete and undelete.
• Work with both COs and SOs.
• Before Triggers - update validate values before
saving.
• After Triggers - have access to field values
automatically set like ID or lastUpdated.
• No before undelete event.
• Triggers can be set to active or inactive.
• Specified order of events when a trigger
executes.

Trigger Considerations
• All triggers are bulk triggers & can process
multiple records at a time.
• All triggers run as System by default. Override it
by using "with sharing" keywords.
• Triggers cannot contain the static keyword
• Triggers can only contain keywords applicable to
an inner class.
• addError method prevents DML events from
taking action on particular records.

Implicit Variables in Triggers
• Trigger.new, Trigger.newMap, Trigger.old,
Trigger.oldMap, isInsert, isUpdate, isExecuting, …
• Trigger.newMap and Trigger.oldMap map IDs to
sObjects.
• Trigger.new is a collection. When used as a bind
variable in a SOQL query, Apex transforms the records
into corresponding ids.
Example:
Contact[] cons = [SELECT LastName FROM Contact
WHERE AccountId IN :Trigger.new];

Trigger example
trigger validateTimecard on Timecard__c
(
before insert,
before update
)
{
// Apex code block
}

Batch Processing in Triggers
• Always try to bulkify a trigger.
• Bulkifying a trigger – is the process of hardening a trigger
to accept a batch of records.
• triggers can always be invoked with a list of records and
should be optimized accordingly.
• Batches can be up to 200 records.
• Example:
List<Resource__c> toInsert = new List<Resource__c>();
for (Contact contact : contacts) {
toInsert.add(new Resource__c(
Name = contact.FirstName + ' ' + contact.LastName));
}
insert toInsert;

Error Handling in Triggers
• Strings describing validation errors can be
added to individual records or fields using the
addError method. Force.com continues to
process the batch, collecting any additional
errors, and then rolls back the transaction and
returns the errors to the initiator of the
transaction.
• All changes are rolled back when there is an
uncaught exception.

Database Security in Apex
• Apex always runs in a privileged, system
context that gives it access to read and write
all data.
• Where full access is not appropriate, Apex
provides the with sharing keyword.

OO Features
• Quite similar to Java.
• Automatic properties: properties with no
code body. When no code body is present, the
getter and setter logic is implied.
• Example:
public Integer cost { get; set; }
• Access modifiers on automatic properties:
public Integer readOnly { get; private set; }
public Integer writeOnly { private get; set; }

Access Modifiers
• Classes: public (visible to the app namespace)
and global (visible to all app namespaces)
• If an inner class is global, its outer class is
required to be global.
• Methods and Properties: private, protected
(class and sub-classes), public and global.
• If a method is global, its class must be global as
well.
• If no access modifier is provided, the method or
variable is private.

Polymorphism
• The parent class must specify the virtual or
abstract keywords on the methods to be
overridden.
• In the subclass, the override keyword is used
on the virtual or abstract methods to declare
that they’re replacing implementations in the
parent class.

Debug Log
• Cannot step through the code & set breakpoints.
• A debug log records database operations, system processes, and errors that occur
when executing a transaction or while running unit tests.
• The system generates a debug log for a user every time that user executes a
transaction that is included in the filter criteria.
• You can retain and manage the debug logs for specific users.
• Each entry written to the log is assigned a debug log category and level.
• Debug log categories: Database, Apex Code, Apex Profiling, Callout, System,
Validation, Visualforce, Workflow.
• Debug log levels: Error, Warn, Info, Debug, Fine, Finer and Finest. (EWIDFFF)
• To view saved debug logs, click Your Name | Setup | Monitoring | Debug Logs.

Limits of Debug Logs
• Once a user is added, that user can record up to 20
debug logs. After a user reaches this limit, debug logs
stop being recorded for that user. Click Reset on the
Monitoring Debug logs page to reset the number of
logs for that user back to 20. Any existing logs are not
overwritten.
• Each debug log can only be 2 MB. Debug logs that are
larger than 2 MB in size are truncated.
• Each organization can retain up to 50 MB of debug
logs. Once your organization has reached 50 MB of
debug logs, the oldest debug logs start being
overwritten.

Debug Log Execution & Code Units
• An execution unit is equivalent to a transaction. It
contains everything that occurred within the
transaction. The execution is delimited
by EXECUTION_STARTED and
EXECUTION_FINISHED.
• Code Unit is a discrete unit of work within a
transaction. Units of code are indicated
by CODE_UNIT_STARTED and CODE_UNIT_FINISH
ED. Units of work can embed other units of work.

Debug Log Example
EXECUTION_STARTED
CODE_UNIT_STARTED|[EXTERNAL]execute_anonymous_apex
CODE_UNIT_STARTED|[EXTERNAL]MyTrigger on Account trigger event
BeforeInsert for [new]
CODE_UNIT_FINISHED <-- The trigger ends
CODE_UNIT_FINISHED <-- The executeAnonymous ends
EXECUTION_FINISHED

Debug Log Line
• Log lines are made up of a set of fields, delimited by a pipe (|).
The format is:
• timestamp: consists of the time when the event occurred and a
value between parentheses. The time is in the user's time zone and
in the format HH:mm:ss.SSS.
• event identifier: consists of the specific event that triggered the
debug log being written to, such
as SAVEPOINT_RESET or VALIDATION_RULE, and any additional
information logged with that event, such as the method name or
the line and character number where the code was executed.
• Example:
11:47:46.038 (38450000)|USER_DEBUG|[2]|DEBUG|Hello World!

Debug Log Levels – Execution Path and
Overrides
• When you override the debug log levels for a
class or trigger, these debug levels also apply
to the class methods that your class or trigger
calls and the triggers that get executed as a
result.
• All class methods and triggers in the execution
path inherit the debug log settings from their
caller, unless they have these settings
overridden.

View Logs
• In the Force.com IDE, a user interface is provided
for the debug log on the right side of the Execute
Anonymous and Test Runner views. It displays
debug log entries resulting from code executed
by these views.
• Each has a text area for the log entries, a drop-down
list of debug log categories, and a slider for
adjusting the log level.
• Each category receives its own independent log
level, although only one can be shown at a time
in the user interface.

Unit Testing
• Test Coverage = 100 x (l.o.c. executed during test runs /
total l.o.c.). Expressed as a percentage. The loc is from
triggers and classes.
• Test Methods – static void methods in an outer class
with the testMethod keyword added.
• Designate a class with the @isTest annotation to treat
all it’s methods as test methods. Classes annotated
with isTest must be declared as private.
• Tests subjected to same governor limits as Apex code.
• Each test method is independently subject to governor
limits and not cumulative with other test methods in a
class.

Unit Testing (contd…)
• A test is successful if it executes without encountering
an uncaught exception.
• System.assert( boolean expression ). If the boolean
expression is false, a System.Exception is thrown and
the test fails.
• All database modifications occurring during execution
of a test method are rolled back after the method is
completed.
• Best practices: create own test data in a setup phase
before tests are executed and limit assertions to that
test data. Create environment agnostic test case data.

Testing Governor Limits
• Test governor limits using system static
methods provided by Apex - Test.startTest and
Test.stopTest.
• Useful when working with large data sets.
• These static methods allow a test method to
separate the Apex resources and governor
limits being used to prepare and initialize the
dataset from the resources and limits used
during the actual test execution.

Test.start & Test.stop Methods
• Test.startTest - marks the point in your test code when your test
actually begins. Each test method is allowed to call this method
only once.
• All of the code before this method should be used to initialize
variables, populate data structures, and so on, allowing you to set
up everything you need in order to run your test.
• After you call this method, you get a fresh set of governor limits for
the remainder of the test until you call Test.stopTest.
• Use Test.stop method in conjunction with the startTest method.
Each test method is allowed to call this method only once. After
calling this method, any post assertions are done in the original
context.

System.runAs(user) { …}
• Generally, all Apex code runs in system mode, and the
permissions and record sharing of the current user are
not taken into account.
• System.runAs() lets you write test methods that change
user contexts to either an existing user or a new user.
All of that user's record sharing is then enforced.
• System.runAs() can only be used in a test method.
• The original system context is started again after all
runAs() test methods complete.
• System.runAs() will test and verify proper data sharing
and data access but does not validate CRUD or Field
Level Security permissions.

Strategies to test Controllers
• Directly invoke controller getters/setters and
action methods.
• Setup constructor code to read URL
arguments to establish controller state or
perform actions.
• Verify data in the database using SOQL and
SOSL queries.
• Use System.runAs blocks to simulate different
users; System.runAs(user) {block; }.

Testing Visualforce Custom Controllers
& Controller Extensions
Example:
public static testMethod void testMyController() {
PageReference pageRef = Page.success;
Test.setCurrentPage(pageRef);
MyController controller = new MyController();
String nextPage = controller.save().getUrl();
System.assertEquals('/apex/failure?error=noParam', nextPage);
ApexPages.currentPage().getParameters().put('qp', 'yyyy');
controller = new MyController();
controller.setLastName('lastname');
controller.setFirstName('firstname');
nextPage = controller.save().getUrl();
System.assertEquals('/apex/success', nextPage);
}

Testing Triggers
• Best Practice for trigger development: Keep
the trigger’s code block as small as possible.
• Place code in a separate class for easier
maintenance and to encourage code reuse.

Running Tests
• There are 2 primary ways to execute test methods:
• Salesforce UI
1. Via the Apex Test Execution Page
2. Via the list of classes under Setup > Develop > Apex
Classes
3. Via a specific class under Setup > Develop > Apex
Classes > Class Name
• Metadata API
1. via Force.com IDE
2. runTests() method in the SOAP API

Testing – Best Practices
• Strive for 100% code coverage instead of the 75%
requirement.
• Write portable tests that do not rely on data
specific to an environment or org.
• Should not commit to DB nor send emails.
• Use the runAs method to test with different user
contexts.
• Test methods should execute Apex code with
large data sets. Running tests in bulk mode will
test the governor limits of your code.

SFDC Introduction to Apex

More Related Content

What's hot (20)

Similar to SFDC Introduction to Apex (20)

More from Sujit Kumar (20)

Recently uploaded (20)

SFDC Introduction to Apex

Editor's Notes