Apex Triggers in Salesforce: A Complete Guide

40 Comments

1. Completed Assignment for Day 5
   I have created one trigger “InvoiceAmountUpdate” and one class “InvoiceAmountUpdateHandler”

2. Completed Day 5 Assignment

3. Day 5 Assignment Completed

4. Episode 5 – Demystifying Apex Triggers Assignment Completed!

5. Completed Day 5 assignment

6. Day 5 Assignment is completed

7. completed

   • 8 more to go

   • Can someone update all the solution?

8. completed assignment 5

9. Solution plz

   • After contest over

10. assignment 5 completed

11. Assignment 5 Completed

12. Day 5 Assignment is completed

13. Day 5 Assignment is completed

14. Solution for Assignment : Trigger on Invoice Line Item which will add sum of all child records to parent Invoice:

    trigger AddInvoiceItems on Invoice_Line_Item__c ( after insert, after update, after delete ) {

    List ListIds = new List();

    if ( Trigger.isInsert || Trigger.isUpdate ) {

    for ( Invoice_Line_Item__c item : Trigger.New ) {
    if ( Trigger.isInsert || ( Trigger.isUpdate && Trigger.OldMap.get(item.ID).price__c!=item.price__c) ) {

    listIds.add(item.Invoice__c);

    }
    }
    }

    if(Trigger.isDelete)
    {
    for( Invoice_Line_Item__c item : Trigger.Old ) {

    listIds.add(item.Invoice__c);

    }
    }

    Map TotalPriceMap = new Map();

    for ( Invoice_Line_Item__c item : [ SELECT Id, price__c, invoice__c FROM Invoice_Line_Item__c WHERE invoice__c IN : ListIds ] ) {

    Decimal totalPrice = 0;
    if( TotalPriceMap.containsKey ( item.invoice__c ) )
    totalPrice = TotalPriceMap.get( item.invoice__c );
    totalPrice = totalPrice + item.price__c;
    TotalPriceMap.put(item.invoice__c,totalPrice);
    }

    List updateInvoice = new List();
    for ( Id invoiceId : TotalPriceMap.KeySet() ) {
    Invoice__c inv = new Invoice__c ( Id = invoiceId );
    inv.Total_Amount__c = TotalPriceMap.get( invoiceId );
    updateInvoice.add(inv);
    }

    if ( updateInvoice.size() > 0 )
    Update updateInvoice;

    }

    • HI bro, i have one question, you have declared empty map . since it is empty how you are searching using containskey

      • Thanks for pointing out. It should be like this:

        Map TotalPriceMap = new Map();

        I believe, datatype got missed while I pasted my solution.
        I am sorry about it. I will check and correct it.

        Thanks again!

    • Corrections to the code – Please check comments below

    • trigger UpdateInvoice on InvoiceLineItem__c (before insert,before update,before delete,after insert, after update, after delete, after undelete)
      {
      List ListIds = new List();

      if ( Trigger.isInsert || Trigger.isUpdate ) {

      for ( InvoiceLineItem__c item : Trigger.New ) {
      if ( Trigger.isInsert || ( Trigger.isUpdate && Trigger.OldMap.get(item.ID).price__c!=item.price__c) ) {

      listIds.add(item.Invoice__c);

      }
      }
      }

      if(Trigger.isDelete)
      {
      for( InvoiceLineItem__c item : Trigger.Old ) {

      listIds.add(item.Invoice__c);

      }
      }

      Map TotalPriceMap = new Map();

      for ( InvoiceLineItem__c item : [ SELECT Id, price__c, invoice__c FROM InvoiceLineItem__c WHERE invoice__c IN : ListIds ] ) {

      Decimal totalPrice = 0;
      if( TotalPriceMap.containsKey ( item.invoice__c ) )
      totalPrice = TotalPriceMap.get( item.invoice__c );
      totalPrice = totalPrice + item.price__c;
      TotalPriceMap.put(item.invoice__c,totalPrice);
      }

      List updateInvoice = new List();
      for ( Id invoiceId : TotalPriceMap.KeySet() ) {
      Invoice__c inv = new Invoice__c ( Id = invoiceId );
      inv.TotalAmount__c = TotalPriceMap.get( invoiceId );
      updateInvoice.add(inv);
      }

      if ( updateInvoice.size() > 0 )
      Update updateInvoice;
      }

      • Keep up the good work

15. HI bro, i have one question, you have declared empty map . since it is empty how you are searching using containskey

    • Facing some issue with code within angle brackets after I posted comment.

      Correction:
      List ListIds = new List(); // Id within angle brackets after List
      Map TotalPriceMap = new Map(); // Id,Decimal within angle brackets after Map
      List updateInvoice = new List(); // Invoice__c within angle brackets after List

16. Noticed some issues with posted code : I noticed code(data type) within angle brackets got removed after I posted it. I am sorry about this.
    Please add following datatype ( written after backslash ) within angle bracket after List or Map

    Correction:

    List ListIds = new List(); // Add Id within angle brackets after List

    Map TotalPriceMap = new Map(); // Add Id , Decimal within angle brackets after Map

    List updateInvoice = new List(); // Add Invoice__c within angle brackets after List

17. Code for Assignment Day 5
    ——————————–

    trigger InvoiceAmountUpdate on Invoice_Line_Item__c (after insert,
    after update,
    after delete) {

    String invoiceId = ”;
    if(Trigger.isInsert || Trigger.isUpdate) {
    for(Invoice_Line_Item__c invoiceLineItem : Trigger.new) {
    if(invoiceLineItem.Invoice__c != null) {
    invoiceId = invoiceLineItem.Invoice__c;
    }
    }
    }
    if(Trigger.isDelete){
    for(Invoice_Line_Item__c invoiceLineItem : Trigger.old) {
    if(invoiceLineItem.Invoice__c != null) {
    invoiceId = invoiceLineItem.Invoice__c;
    }
    }
    }
    if(invoiceId != ”) {
    InvoiceAmountUpdateHandler.updateInvoiceAmount(invoiceId);
    }
    }

    —————————————————————————–

    public class InvoiceAmountUpdateHandler {
    public static void updateInvoiceAmount(String invoiceId) {
    List items = new List();
    items = [select Id,price__c from Invoice_Line_Item__c where Invoice__c = :invoiceId];
    Decimal amount = 0;
    for(Invoice_Line_Item__c item : items) {
    amount = amount + item.Price__c;
    }
    Invoice__c invoice = new Invoice__c();
    invoice.Id = invoiceId;
    invoice.Total_Amount__c = amount;
    update invoice;

    }
    }

    • Hi! I have written a code for trigger assignment task and its working well for insert and update. Can you please tell me whether I need to modify my code for better results..

      Parent: Invoice__c
      Child: Invoice_Line_Item__c

      Trigger code:
      trigger Invoice_Line_Item__cTrigger on Invoice_Line_Item__c (after insert, after Update) {

      if((trigger.IsInsert == true && Trigger.Isafter == true) ||(trigger.IsUpdate == true && Trigger.Isafter == true)){

      Invoice_Line_ItemHandler.AmoutUpd(trigger.new);
      }
      }

      APEXHANDLER::

      public class Invoice_Line_ItemHandler {

      public static list P_id = new list();
      public static decimal amount=0;

      public static void AmoutUpd(list ChildRec){

      for(Student__c Pid : StuRec){

      if(pid.Teacher_name__c != null){

      P_id.add(pid.Invoice_name__c);
      }
      }
      list Rec = [SELECT Total_amout__c,name,(SELECT Invoice_name__c,price__c FROM Invoice_Line_Item__r) FROM Invoice__c WHERE ID IN :P_id];

      for(Invoice__c a: Rec){

      for(Invoice_Line_Item__c b: a.Invoice_Line_Item__r){

      amount = amount+ b.price__c ;
      }

      a.Total_amout__c = amount;
      }
      update Rec;
      }

      }

    • Hey, if we want to delete some record from Invoice line item and again add the record in Invoice line item and i have created one more filed at Invoice line item that is count of line Item in particular Invoice then count should be increase… how to do it??

18. hello
    I copied the Handler Class from above into the Dev console but I receive Unexpected token ‘List’. error for this statement:
    List items = new List();

    What am i missing here?

    -jim

19. Logic for Trigger
    ================
    public class ApexHourTriggerAssignment {

    public static void updateInvoceObjectField(List lstinvln){
    Decimal amount=0;
    Set liStIds = new Set();
    for (Invoice_Line_Up__c ilu :lstinvln) {
    if(ilu.Invoice_Name__c != null) {
    liStIds.add(ilu.Invoice_Name__c);
    }
    }
    List ListInvoice = [Select id, Total_Amount__c, (select id, price__c from Invoices_Line_up__r)
    from Invoice__c Where Id IN :liStIds];
    ListListInv = new List();
    For(Invoice__c inv : ListInvoice){
    for(Invoice_Line_Up__c ilu1 : inv.Invoices_Line_up__r){
    amount = amount + ilu1.price__c;
    }
    inv.Total_Amount__c = amount;
    ListInv.add(inv);
    }
    update ListInv;
    }
    }

    ======================
    trigger ApexHourTriggerAssignmentTrigger on Invoice_Line_Up__c (After insert,After Update) {

    ApexHourTriggerAssignment.updateInvoceObjectField(Trigger.new);
    }

    • Keep learning

    • Congratulation. I hope this Trigger example helped you to learn Salesforce Trigger

20. My solution for assignment.

    trigger TotalInvoiceAmount on Invoice_Line_Item__c (after insert) {

    Map UniqueInvoiceToUpdate = new map(); // To maintain unique sobject to be updated
    Map TotalAMount = new Map(); // To maintain the updated amount of each invoice sobject

    ListInvoiceToUpdate = new List(); // final list to perform dml update operation
    Invoice__c ParentInvoice;

    for (Invoice_Line_Item__c currentInvoiceItem : Trigger.New) {

    ParentInvoice = [select id, Total_Amount__c from Invoice__c where Id = :currentInvoiceItem.Invoice__c LIMIT 1][0];

    // Check if we have updated total value of invoice in previous iterations:
    if (TotalAmount.get(ParentInvoice.Id) != null) {

    // if yes, add the current amount of invoice line item to the previous updated invoice object.
    // Not that, we have not commit to database yet. Hence we are retrieving updated amount from map and not from sobject’s Total amount field
    ParentInvoice.Total_Amount__c = TotalAmount.get(ParentInvoice.Id) + currentInvoiceItem.Amount__c;
    }
    else {
    // We haven’t saved total amount in map yet.
    // Add current invoice line item amount to total amount of invoice object.
    ParentInvoice.Total_Amount__c += currentInvoiceItem.Amount__c;
    }
    // save updated total amount of invoice object in map
    TotalAmount.put(ParentInvoice.Id, ParentInvoice.Total_Amount__c );

    // update invoice object’s map.
    UniqueInvoiceToUpdate.put(ParentInvoice.Id, ParentInvoice);
    }

    // iterate UniqueInvoiceToUpdate map to put those invoice objects in list.
    for (Invoice__c I : UniqueInvoiceToUpdate.values()){
    InvoiceToUpdate.add(I);
    }

    // update list.
    update InvoiceToUpdate;
    }

    Any better solution?

    • Good job. I hope this session helped you to understand the Apex Trigger in Salesforce.

21. Hello there, I have clarification on assignment –
    i)create custom object invoice with field total amount
    ii)create child object invoice line item with lookup relationship to invoice
    iii)add price field into invoice line item
    ​​​​​​​
    I have created ‘invoice’ object and field ‘total amount’
    now how to create lookup relation on child object
    I’m confused whether we can create relationship on object, it can be created on fields only as I know or maybe something I don’t know on this.
    can anyone plz guide.

22. Apex class
    —————
    public class AddTotalAmountOnInvoice {

    public static void addInvoiceLineItemTotalAmount(List slist){
    List invoiceId=new List();
    for(Invoice_Line_Item__c ids:slist){
    invoiceId.add(ids.Invoice__c);
    }
    Map addAmountList = new Map();
    for(Invoice_Line_Item__c inv:[SELECT Id, Name,price__c ,Invoice__c FROM Invoice_Line_Item__c WHERE Invoice__c=:invoiceId]){
    Decimal num=inv.price__c;
    if(!addAmountList.containsKey(inv.Invoice__c)){
    addAmountList.put(inv.Invoice__c,num);
    }
    else{
    Decimal num2=addAmountList.get(inv.Invoice__c)+num;
    addAmountList.put(inv.Invoice__c,num2);
    }
    }
    System.debug(‘invocie:’+addAmountList);
    List amountList = new List();
    for(Invoice__c invc:[SELECT Id, Total_Amount__c FROM Invoice__c WHERE ID IN:addAmountList.KeySet()]){
    if(addAmountList.containsKey(invc.Id)){
    invc.Total_Amount__c = addAmountList.get(invc.Id);
    amountList.add(invc);
    }
    }
    if(amountList!=NULL && amountList.size()>0){
    update amountList;
    }
    }
    }
    ——————–
    Trigger class
    —————
    trigger TotalAmount on Invoice_Line_Item__c (before insert,before update,before delete,after insert, after update, after delete, after undelete) {
    if(Trigger.isBefore){
    if(Trigger.isInsert){
    AddTotalAmountOnInvoice.addInvoiceLineItemTotalAmount(Trigger.new);
    }
    if(Trigger.isDelete){
    AddTotalAmountOnInvoice.addInvoiceLineItemTotalAmount(Trigger.new);
    }
    }
    if(Trigger.isAfter){
    if(Trigger.isUpdate){
    AddTotalAmountOnInvoice.addInvoiceLineItemTotalAmount(Trigger.new);
    }
    if(Trigger.isInsert){
    AddTotalAmountOnInvoice.addInvoiceLineItemTotalAmount(Trigger.new);
    }
    if(Trigger.isDelete){
    AddTotalAmountOnInvoice.addInvoiceLineItemTotalAmount(Trigger.new);
    }
    }
    }

    • Glad you used the Trigger handler pattern. Keep up the good work.

23. In Apex Trigger Context Variable list
    you missed isUndelete
    https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_triggers_context_variables.htm#:~:text=records%20were%20saved.-,isUndelete,-Returns%20true%20if

24. Context Variable has some mistakes
    example
    1.
    isInsert It tells if the code’s current context is triggered or not.
    2.isExecuting It returns true if the trigger fires on the update operation.
    3.isUpdate It returns true if the trigger fires on the delete operation.
    4. isDelete It returns true if the code is running in the Before context.
    5. isBefore It returns true if the code is running in the After context.

    and many more,
    Can you please look at this blog, I think some ups and down,

25. Context Variable has some issue
    example
    1.
    isInsert It tells if the code’s current context is triggered or not.
    2.isExecuting It returns true if the trigger fires on the update operation.
    3.isUpdate It returns true if the trigger fires on the delete operation.
    4. isDelete It returns true if the code is running in the Before context.
    5. isBefore It returns true if the code is running in the After context.

    and many more,
    Can you please look at this blog, I think some ups and down,