Triggers in salesforce
Last updated on 09th Aug 2022, Blog, Tutorials
What Is Trigger In Salesforce?
A trigger is an Apex script that executes before or after specific data manipulation language (DML) events occur, such as before object records are inserted into the database, or after records have been deleted. Triggers enable you to perform custom actions before or after changes to Salesforce records. A trigger is Apex code that executes before or after the following types of operations like insert, update, and delete.
There Are Two Types Of Triggers:
- Before triggers: It is used to update or validate record values before saved to the database.
- After triggers: It is used to access values of the record that are stored in the database and use this value to make changes with other records.After trigger records are read-only.
- Trigger trigger Name on sObject(Trigger event)
- {
- //logic
- }
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Bulky Trigger
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All triggers are bulk triggers by default and can process multiple records at a time. You should always plan on processing more than one record at a time. Bulk triggers can handle both single record updates and bulk operations like:
- Data import
- com Bulk API calls
- Mass actions, such as record owner changes and deletes
- Recursive Apex methods and triggers that invoke bulk DML statements
A trigger is Apex code that executes before or after the following types of operations:
- insert
- update
- delete
- merge
- upsert
- undelete
When to use salesforce triggers
We should use triggers to perform tasks that can’t be done by using the point-and-click tools in the Salesforce user interface. For example, if validating a field value or updating a field on a record, use validation rules and workflow rules instead.
What is Trigger Syntax?
- trigger TriggerName on ObjectName (trigger_events) {
- code_block
- }
Trigger events in salesforce?
A trigger is a set of statement which can be executed on the following events. In above trigger events one or more of below events can be used with comma-separated.
Here is a list of trigger events in salesforce
- before insert
- before update
- before delete
- after insert
- after update
- after delete
- after undelete
Trigger Context Variables
Variable | Usage |
---|---|
isExecuting | Returns true if the current context for the Apex code is a trigger, not a Visualforce page, a Web service, or an executeanonymous() API call. |
isInsert | Returns true if this trigger was fired due to an insert operation |
isUpdate | Returns true if this trigger was fired due to an update operation |
isDelete | Returns true if this trigger was fired due to a delete operation. |
isBefore | Returns true if this trigger was fired before any record was saved. |
isAfter | Returns true if this trigger was fired after all records were saved. |
isUndelete | If a record is recovered from the recycle bin it returns trigger true. |
new | Returns a list of the new versions of the sObject records. This sObject list is only available in insert, update, and undelete triggers, and the records can only be modified before triggers. |
newMap | A map of IDs to the new versions of the sObject records.This map is only available in before update, after insert, after update, and after undelete triggers. |
old | Returns a list of the old versions of the sObject records.This sObject list is only available in update and delete triggers. |
oldMap | A map of IDs to the old versions of the sObject records.This map is only available in update and delete triggers. |
size | The total number of records in a trigger invocation, both old and new. |
Actions of Different Trigger Events
The following are lists of considerations about actions of different trigger events:
Trigger Event | Can change fields using trigger.new | Can update original object using an update DML operation | Can delete original object using a delete DML operation |
beforeinsert | Allowed. | Not applicable. | Not applicable. |
afterinsert | Not allowed. A runtime error is thrown, as trigger.new is already saved. | Allowed. | Allowed, but unnecessary. The object is deleted immediately after being inserted. |
beforeupdate | Allowed. | Not allowed. A runtime error is thrown. | Not allowed. A runtime error is thrown. |
afterupdate | Not allowed. A runtime error is thrown, as trigger.new is already saved. | Allowed. | Allowed. |
beforedelete | Not allowed. A runtime error is thrown. trigger.new is not available before delete triggers. | Allowed. | Not allowed. |
afterdelete | Not allowed. A runtime error is thrown. trigger.new is not available after delete triggers. | Not applicable. The object has already been deleted. | Not applicable. The object has already been deleted. |
afterundelete | Not allowed. A runtime error is thrown. trigger.old is not available after undelete triggers. | Allowed. | Allowed, but unnecessary. The object is deleted immediately after being inserted. |
Insert Operation Before Insert:
- This trigger will be fried when a new record is going to be saved in the database.
- In before insert, trigger. New stores a new list of records which is going to be inserted.
Example
- Trigger Duplicate Name on Contact (before insert, before update)
- {
- set<String> lastName = new set<String>();
- set<String> setname = new set<String>();
- for(Contact con : Trigger.new)
- {
- lastName.add(con.email);
- }
- for(Contact con : [select lastName from contact where email in : lastName])
- {
- setname.add(con.lastName);
- }
- if(Trigger.isInsert||Trigger.isUpdate)
- for(contact a:trigger.new)
- {
- if(setname.contains(a.lastName))
- {
- a.lastName.adderror(‘This email already exists’);
- }
- }
- }
After Insert
- After insert trigger will be fired after new record inserted successfully in database.
- New is going to hold a new record which is inserted into the database.
- After insert trigger is read only operation. We can do DML operations on new records which are inserted into the database.
- Trigger After Insert Example on Account (after insert)
- {
- for(Account acc: Trigger.new)
- {
- Account oldAcc = Trigger.oldMap.get(acc.Id);
- if(oldAcc.phone != acc.phone)
- {
- List<Contact> conList = [ SELECT Id, AccountId, phone from Contact where AccountId = :acc.Id];
- List<Contact> newids = new List<Contact>();
- for(Contact con: conList)
- {
- if(con.phone != acc.phone)
- {
- con.phone = acc.phone;
- newids.add(con);
- }
- }
- if (!newids.isEmpty())
- {
- update newids;
- }
- }
- }
- }
Update Event There are two types of events
- Before update
- After Update
Trigger. Old and trigger. New are update events in salesforce.
Read: What Apex Email in Salesforce?
- New: Trigger. New is going to hold the list of records which going to be updated.
- Old: Trigger. Old is going to hold the set of old values which are going to be updated.
Before Update
It’s going to store the set record before updating to the database.
- Trigger update before Example on Contact (before update)
- {
- list<account> acclist = new list<account>();
- for(contact acc:trigger.old){
- account c = new account();
- c.Name=acc.lastname;
- c.Phone=acc.phone;
- acclist.add(c);
- }
- insert acclist;
- }
After update
- After the update trigger will be fired when the changes that we have made are saved to the database.
- In the after update trigger operation we can only read the data from trigger.
- If we want to make any changes we need to perform DML operation.
Example
- Trigger update Contact on Account (after update)
- {
- if(trigger.IsAfter && trigger.IsUpdate){
- set<id>ids = new set<id>();
- list<contact>conlist = new list<contact>();
- for(account a:trigger.new){
- ids.add(a.id);
- list<contact>con =[select id,phone,lastName,account.phone from contact where accountid in:ids];
- for(contact c:con){
- c.Phone=c.account.phone;
- conlist.add(c);
- }
- update conlist;
- }
- }
- }
Delete Event There are two events in delete
- Before Delete
- After Delete
Trigger. Old
This is going to hold the records which are going to be deleted. These records are read only by operation.
Before Delete example
- Trigger Account Delete on Account (before delete)
- {
- for(Account Acc:trigger.old)
- {
- acc.Name.addError(‘Account cannot be deleted’);
- }
- }
After Undelete
- When we are undeleting records from the recycle bin after undeleting operation required.
- New is going to store the record which is undeleting from the recycle bin.
Trigger.newMap and Trigger.oldMap
Trigger.oldMap
A map of IDs to the old version of the sObject records. Note that this map is only available in update and delete triggers.
- Trigger Map Demo on Account (before update)
- {
- Map<Id,account> accMap = new Map<Id,account>();
- accMap = trigger.oldMap;
- for(account acc : trigger.new)
- {
- account oldvalue = new account();
- oldvalue = accMap.get(acc.Id);
- if(acc.phone != oldvalue.phone)
- {
- acc.phone.addError(‘Phone cannot be changed’);
- }
- }
- }
Trigger.newMap:
A map of IDs to the new version of the sObject records. Note that this map is only available in before update, after insert and after update triggers.
- Trigger update contact Phone on Account (before update)
- {
- if(trigger.isbefore && trigger.isupdate){
- map<id,account> mapcon = trigger.newmap;
- list<contact> cont = new list<contact>();
- list<contact> con = [select id,phone,accountid from contact where accountid in : mapcon.keyset()];
- for(contact c : con){
- c.phone = mapcon.get(c.accountid).phone;
- cont.add(c);
- }
- update cont;
- }}
Types of Salesforce Triggers
Actually, there are no different types of triggers – but as the triggers are used before or after certain operations, they are considered to be of two types.
- Before triggers
- After triggers
Before triggers – These triggers run before the activity like updating or inserting a record into a database.
After triggers – These triggers are run for accessing the field values set by the system. They are also used to affect the changes in the records. For instance, after triggers are often used when dealing with audit tables and also when you handle asynchronous events with a queue. These after-triggers are considered read-only.
Syntax of a Trigger
The definition of a trigger starts with the trigger catchphrase and then followed by the trigger name.
- trigger < TriggerName> on ObjectName (< Trigger_Events>)
- {
- Any required code is written here.
- }
The Trigger_Events can be a comma-separated list of any events like – before insert, before update, before delete, after insert, after delete, after update, or after undelete.
Considerations for implementation of Triggers in Salesforce
Certain considerations are to be kept in mind when implementing Salesforce triggers. Here are some of them.
- Before and after insert are fired by upsert triggers. Also, they fire the before and after update triggers whenever applicable.
- For the losing records, before and after delete are fired by the merge triggers and for the winning records before and after update triggers are considered.
- If the record has been undeleted and the trigger is performed after it, then it works only with certain specific objects.
- Till the end of the trigger, no records of field history are made. So, you cannot notice the history of current transactions when you ask for the field history in a trigger.
- The permissions of the current user are required to know the field history tracking. For instance, if a user doesn’t have a right to edit an object, but a trigger is activated still by the user to change an object with enabling the history tracking, then there will be no records of the history of the change.
- Asynchronous calls are to be made to avoid the blocking of the trigger process when waiting for the response of external service.
Trigger Context Variables
There are certain context variables which implicit the triggers – they help developers to access the run-time context.
- Trigger.isBefore – It gives true if this trigger ends before any record was spared.
- Trigger.isAfter – It mentions true value if this trigger ends after all records were spared.
- Trigger.isInsert – It avails true if it was fired for some insert operation, from the Apex, API, or the Salesforce User Interface.
- Trigger.isUpdate – It gives a true value when an update operation is done upon using this trigger.
- Trigger.isDelete – It gives genuine answer when one uses this trigger during any delete operations through Apex, API, or Salesforce user interface.
- Trigger.isUndelete – It gives a genuine things when one fires this trigger after recovering a record from the Recycle Bin.
- Trigger.new – new versions of the sObject records are showed with the help of it.
- Trigger.old – It provides a list of sObject records’ old versions. However, the list is only available in update and delete triggers.
- Trigger.newMap – It gives a map of IDs for the sObject records’ new versions. However, it is only found in before update, after update, after insert, and after undelete triggers.
- Trigger.oldMap – It gives a map of IDs to the sObject records’ old versions and is there in update and delete triggers.
- Trigger.oldMap – It gives a map of IDs to the sObject records’ old versions and is there in update and delete triggers.
- Trigger.size – It gives the total number of records (both old and new records) upon calling.
Having an idea on these triggers is very much important for developers and other Salesforce users to manage the appropriate functions accurately.
Summary
Apex triggers can help you to perform customized operations on a database. With this blog, we have learned a few facts about Trigger in Salesforce.
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