Triggers in Salesforce | Salesforce Apex Triggers | Salesforce Tutorial | Edureka Rewind

Key Takeaways

hey guys this is Aman from edureka and I welcome you all to this interesting session on triggers in Salesforce but before we get started I would like to address the agenda for today's session we will start the session off by understanding what exactly is triggers in Salesforce then we'll learn about what are the different types of triggers and the events in Salesforce triggers moving on we will understand the syntax to write a trigger in Salesforce and what are context variable in Salesforce triggers next we'll take a look at the things to consider before implementing a Salesforce trigger finally we will conclude the session with the demo part where I will show you how you can create a trigger in Salesforce now moving on to a first topic what are triggers in Salesforce triggers in Salesforce are known as Apex triggers Apex triggers are a piece of code which enables you to perform custom action before or after the change of any Salesforce record these changes could be anything like insertion of Records or updation of Records or deletion of Records you can use triggers to perform operation based on a specific condition so only when the condition occurs the triggers are executed or fired triggers could be used to modify records or restrict any certain operation from happening like restricting addition of a field or deletion of a field now you can use triggers to do anything that you used to do in Apex including executing soql and DML statements or calling Custom Apex methods triggers can be defined for top level standard objects such as accounts or contacts and even for custom objects and some standard chart objects so if any changes occurs to these objects you can set a trigger to perform a set of functionalities now another point you need to remember is triggers are active by default when created Salesforce automatically fires the triggers when a specific database event occurs so I guess you have understood something about Salesforce trigger so now let us move on to next topic which is the types of Salesforce trigger so basically there are two types of triggers in Salesforce the first one is the before trigger and the second one is the after trigger now as the before tracker name suggests that used to perform a task before a record is inserted or updated or deleted these triggers are usually used to update or validate record values before they are saved to the database next after triggers are used to access field values that are already set by the system such that and Records ID or date or phone number field and to affect changes in other records as well these triggers are usually used to update or validate record values after they are saved to the database also after triggers are read only you cannot make any changes to them so these were the two types of triggers in Salesforce so now let us move on to next topic and understand what are the trigger events in Salesforce now as we all know triggers is a set of statement or a piece of code so it can be executed on any of the following events here is the list of trigger events which means now trigger can be fired when the following event occurs so before insertion means your trigger will be fired before the records inserted to the database for example let us say inserting a new lead you can create a trigger which will be fired if the detail of the new lead is same as that of the previous one this way you will avoid the duplication of record so these are the following trigger events the first one is before insert next we have before update and next we have before delay after insert after update after delayed and after undelete you can set a trigger before or after a event occurs you can write a trigger and it will be executed before or after the DML event DML is nothing but insertion updation and deletion you can also add more than one trigger event but there should be Commerce operated now let me explain this better with the next topic which is syntax for Salesforce trigger the syntax of a trigger definition is quite different from a class definition syntax a trigger definition starts with the trigger keyword it is Then followed by the name of the trigger you can name a trigger anything you want next is the Salesforce object that a trigger is associated with this could be anything like leads or contacts or accounts or any other custom objects Salesforce object is known as s object next is a trigger event which we have talked about in the previous topic we can fire a trigger in one or more events but it should be comma separated next is the body of the code which will contain the condition under which it fires so this was the Syntax for writing a trigger in Sage Force now let us execute a small demo to understand this better we will fire a simple trigger before we insert an account and write a message to the debug log so let me just quickly switch to my developer console so here I've signed in into my sales for developer console so the first step is to click on file go to new you have an option here called Apex Trigger so just click on that now we can name a trigger anything we want just name it demo and the S object we're going to select here is account I'm going to click on submit now it's creating a new trigger and you can see the syntax for a trigger the trigger keyboard the name of a trigger on what s object and what trigger event by default it is before insert now if you're just going to display hello world here so for that system dot debug hello world semicolon will just save this next we have to go to a debug open execute an MLs window now here we are going to create a new account a is equal to new account now I have to give a name to our account so we'll just name it test account next insert it so let us execute this now here is the execution log so just click on debug only or you can just scroll down and find debug over here here is the debug so here you can see our message hello world this was just a small quote to explain the Syntax for writing triggers in Salesforce now I guess you have some idea about ch4's trigger syntax let us move on to next topic and understand what are context variable so all trigger Define implicit variables that allows developer to access runtime contacts to explain Us in simple terms context variables are special variables which are managed and created by Salesforce itself which usually gives us the information about the trigger these context variables are required when we want a piece of code inside the trigger to run only for a particular event using this context variable we can specify which piece of code we want to run for which particular event avoiding running all the other pieces of code which are not required to run for a specific event another important point is all context variables are content in the system.rigger class so now let us take a look at the list of context variables in Salesforce trigger the first context variable is is insert this returns True Value if the trigger was fired due to an insert operation for many ch4's user interface or Apex or the apis I would like to show you the syntax here so you can know how exactly can we use context variable in our code so you can see if trigger dot is insert is equal to is equal to True only then the set of code will be executed it basically is like it's checking for a condition and only the condition is true the set of code will be executed else it won't be executed the next context variable is is update this returns true if the trigger was fired due to an update operation next is the is delete now this returns a True Value if the trigger was fired due to an delete operation after this we have is before this returns true if the trigger was fired before and record was saved to the database after this we have is executing this returns true if the current contacts for the Apex code is a trigger and not a visual force page or a web service or an API call the next variable is is after this returns to the trigger was fired after all the records were saved to the database next is is until it this returns true if the trigger was fired after a record was recovered from the recycle bin next we have the new context variable now this returns a list of new version of the Salesforce object records the Salesforce object records is only available in insert update and undelete triggers and the records can only be modified in before triggers after that we have new map new map is a map of IDs to the new version of the Salesforce object records this Maps is only available in before update after insert after update and after run delay triggers after this we have old old returns a list of old version of the Salesforce object records this Salesforce object list is only available in update and delete triggers after this we have old map old map is a map of IDs to the old version of the Salesforce object records this map is only available in update and delete triggers and finally we have the size context variable this Returns the total number of Records in a trigger invocation this would include both old and new so these were the context variable in Salesforce now let us move on to next topic and take a look at the things to consider before implementing a Salesforce trigger the first point is absurd trigger the upside triggers can fire both before and after insert or before and after update trigger as appropriate next we have the merge trigger which can fire both before and after delayed for the deleted records and both before and after update for the updating records the third thing you need to consider before writing a trigger is a trigger cannot have a static keyword in its code next triggers that execute after a record has been undeleted only works for specific objects and not for all the objects the next thing you need to keep in mind is the field history is only updated after the trigger has successfully finished processing the data also any callout should be asynchronous so that trigger does not have to wait for the rest response and the last point is if a trigger completes successfully the changes are committed to the database and if it fails all transaction is rolled back which means it becomes the same as it was before so these were some of the things you need to consider before writing a trigger in Apex now before we move to our next topic I would like to say that triggers can be very helpful it can help you avoid costly data related mistakes inside of Salesforce while streamlining and automating actions that otherwise would have had to be performed manually also Apex triggers help you manage how specific types of data are handled internally which will help you execute a broader overall data maintenance and management strategy Apex triggers help you manage or specific types of data are handled internally which helps you execute a broader overall data management and maintenance strategy with Apex triggers you can also effectively identify and fix common database issues such as merging duplicate accounts standardizing job titles and formatting address and phone number Fields consistently so with this said let let us move on to next topic which is the demo part where I will show you how you can create an Apex Trigger so in this demo we are going to create a trigger so that when someone creates an account the trigger will check if the account name already exists if it does it will throw an error message saying the account name already exists so for this let us go to our Salesforce account developer.salesforce.com so if you're going to the website for the first time here you'll have two options login and sign in if you're a new user you can just create an account it'll just take maybe one or two minutes to create an account after you have logged in you can just go to your name over here and go to my developer account select your username so if you're new to Salesforce this is what a Salesforce console would look like now to go to your developer console just click on the setting over here and select developer console now go to file new Apex Trigger we can name a trigger anything we want we'll just name it account duplication and on what Salesforce object we're going to do this it's on account you will click on submit so here we have the trigger keyboard the name of a trigger and an account object and here we have the trigger event next for a body of our code we are going to create a for Loop first four account object we're going to create an instance for account trigger dot new next list account next creating another instance list account menu is equal to now here we need to select an ID which will compare the new account name with the existing account name so for that let's go to select ID comma name from account when neem is equal to account name this statement will get us the account name now in order to compare and throw an error message we need to check for a condition so for that if my new DOT size here we are using the size context variable which will return the total number of Records in a trigger invocation so if it is greater than 0 it will throw us an error message account.name Lord add Arrow account with same name already existing we're just going to save this so it's saved now let us go to our account section now here you can see I have five account records and these are my account names so now let me try creating a new account with the same name so I click on new and the account name I'll give it as test account so now none of the other fields are mandatory so I'll just click on Save so here you can see we are getting an error message saying account with the same name already existing and you can see how simple it is to create a trigger in Salesforce and with this we have come to the end of the session I hope it was helpful do leave a valuable comment in the comment section below happy learning