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Marco PinderMarco Pinder 

How do I use Maps and Lists on a Trigger?

Hi,

 

I am receiving a error regarding too many SOQL queries when trying to upload several hundred contacts onto a campaign due to a trigger I have created.

 

From reading around the forum I believe that it is because my SOQL statement is inside a FOR loop which loops more times than the governor limits allow. I have read that I should perform the SOQL query outside of the FOR loop and use Lists and Maps to achieve what I require.

 

The trigger is pretty basic at the moment, however my coding skills are very limited and I'm not sure how to implement Lists or Maps.

 

I have posted my trigger below and if someone can instruct me on how to implement the Lists and Maps I would be very grateful.

 

trigger CampaignMemberUpdate on CampaignMember (after insert, after update) {
    for (CampaignMember cm : trigger.new){
        Contact contact = [SELECT Id from Contact where id = :cm.ContactId];
        contact.Campaign_Member_Update_Date__c = cm.LastModifiedDate;
        upsert contact;
    }
}

 

Thanks,

 

Marco

Best Answer chosen by Admin (Salesforce Developers) 
Chamil MadusankaChamil Madusanka

Hi,

 

You have used queries in for loops. That is a basic error in salesforce.

 

Try this code.

 

trigger CampaignMemberUpdate on CampaignMember (after insert, after update) 
{
    Set<Id> contactId = new Set<Id>();
    List<Contact> updated = new List<Contact>();
    for (CampaignMember cm : trigger.new)
    {
        contactId.add(cm.ContactId);
    }
    
    List<Contact> contact = [SELECT Id from Contact where id in: contactId];
    
    for (CampaignMember cm : trigger.new)
    {
        for (Contact con : contact)
        {
            if(con.Id == cm.ContactId)
            {
                con.Campaign_Member_Update_Date__c = cm.LastModifiedDate;
                updated.add(con);
            }
        }
    }
if(updated.size()>0)
{
  upsert updated;
}
}

 If a reply to a post answers your question or resolves your problem, please mark it as the solution to the post so that others may benefit.

 

Chamil's Blog

 

All Answers

Chamil MadusankaChamil Madusanka

Hi,

 

You have used queries in for loops. That is a basic error in salesforce.

 

Try this code.

 

trigger CampaignMemberUpdate on CampaignMember (after insert, after update) 
{
    Set<Id> contactId = new Set<Id>();
    List<Contact> updated = new List<Contact>();
    for (CampaignMember cm : trigger.new)
    {
        contactId.add(cm.ContactId);
    }
    
    List<Contact> contact = [SELECT Id from Contact where id in: contactId];
    
    for (CampaignMember cm : trigger.new)
    {
        for (Contact con : contact)
        {
            if(con.Id == cm.ContactId)
            {
                con.Campaign_Member_Update_Date__c = cm.LastModifiedDate;
                updated.add(con);
            }
        }
    }
if(updated.size()>0)
{
  upsert updated;
}
}

 If a reply to a post answers your question or resolves your problem, please mark it as the solution to the post so that others may benefit.

 

Chamil's Blog

 

This was selected as the best answer
kiranmutturukiranmutturu

trigger CampaignMemberUpdate on CampaignMember (after insert, after update) {

list<contact> lstupdatecons = new list<contact>();

    set<id> sIds = new set<id>();

for (CampaignMember cm : trigger.new){

sIds.add(cm.contactId);

}

list<contact> lstconts = [select id from contact where id in : sIds];

 for(CampaignMember cm : trigger.new){

for(contact objcon : lstconts){

objcon.Campaign_Member_Update_Date__c = cm.LastModifiedDate;

lstupdatecons .add(objcon);

break;

}

 }

if(lstupdatecons .size() > 0)

   update lstupdatecons ;

}

 

try this
kiranmutturukiranmutturu

@chamil

  using the upsert in a loop is also a flaw ...
Chamil MadusankaChamil Madusanka

@ Kiran

Thanks For showing the error. I forgot it. Now I corrected it.

Thanks again kiran
Marco PinderMarco Pinder

@Chamil @Kiran

 

Thanks for your combined input, I have used Chamil's updated code and it appears to work. Have marked the reply as a solution.

 

Regards,

 

Marco