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virkvirk 

update a counter on related standard object insertion or deletion in Master Detail relationship

I am trying to update  a count field on standard object Contact after insert or delete of Lents object. The code is as following but it does not work for deletion:

 

trigger UpdateCount on Lent__c (after insert,after delete) {

List<Contact> counts_toUpdate = new List<Contact>();

Map<String, Integer> contact_newCount_Map=new Map<String, Integer>(); //for each contact the CountNumber

 

if(trigger.isinsert){

List<Lent__c> counts = [select  Contact__c, Contact__r.Count__c

from Lent__c where id IN :Trigger.new FOR UPDATE];

for(Lent__c lent:counts){

contact_newCount_Map.put(lent.Contact__c,  Integer.valueOf(lent.Contact__r.Count__c==null ? 0 : lent.Contact__r.Count__c) + 1);

}

}

else{

List<Lent__c> counts = [select  Contact__c, Contact__r.Count__c

from Lent__c where id IN :Trigger.old FOR UPDATE];

for(Lent__c lent:counts){

contact_newCount_Map.put(lent.Contact__c,  Integer.valueOf(lent.Contact__r.Count__c==null ? 0 : lent.Contact__r.Count__c) - 1);

}

}

 

for(Contact con : [select id, Count__c from Contact WHERE ID IN : contact_newCount_Map.KeySet()]){

con.Count__c=contact_newCount_Map.get(con.id);

counts_toUpdate.add(con);

}

 

update counts_toUpdate;

}

 

Please help in finding the problem.

trigger UpdateCount on Lent__c (after insert,after delete) {
List<Contact> counts_toUpdate = new List<Contact>();
Map<String, Integer> contact_newCount_Map=new Map<String, Integer>(); //for each contact the CountNumber

if(trigger.isinsert){
List<Lent__c> counts = [select  Contact__c, Contact__r.Count__c
from Lent__c where id IN :Trigger.new FOR UPDATE];
for(Lent__c lent:counts){
contact_newCount_Map.put(lent.Contact__c,  Integer.valueOf(lent.Contact__r.Count__c==null ? 0 : lent.Contact__r.Count__c) + 1);
}
}
else{
List<Lent__c> counts = [select  Contact__c, Contact__r.Count__c
from Lent__c where id IN :Trigger.old FOR UPDATE];
for(Lent__c lent:counts){
contact_newCount_Map.put(lent.Contact__c,  Integer.valueOf(lent.Contact__r.Count__c==null ? 0 : lent.Contact__r.Count__c) - 1);
}
}

for(Contact con : [select id, Count__c from Contact WHERE ID IN : contact_newCount_Map.KeySet()]){
con.Count__c=contact_newCount_Map.get(con.id);
counts_toUpdate.add(con);
}

update counts_toUpdate;
}
SfdcStevenSfdcSteven

In an after trigger, requerying the same sobject won't return any objects.  You should instead iterate through the Trigger.old list for the Contact__c ids, gather them into a Set<Id> and then query for the Count__c values directly against the Contact SObject.  Then you can update those contacts with the new count individually.

 

Like this, ish:

Set<Id> contactIds = new Set<Id>
for (Lent__c l : Trigger.old) contactIds.add(l.Contact__c);
Map<Id,Contact> oldContacts = new Map<Id,Contact>([SELECT Count__c From Contact where Id IN :contactIds]);
for (Lent__c lent : counts) contact_newCount_map.put(lent.Contact__c, Integer.valueOf(oldContacts.get(lent.Contact__c).Count__c == null ? 0 : oldContacts.get(lent.Contact__c).Count__c ) -1);

 
virkvirk

Thanks for the help. I added the code you provided as follows:

 

trigger UpdateCount on Lent__c (after insert,after delete) {
List<Contact> counts_toUpdate = new List<Contact>();
Map<String, Integer> contact_newCount_Map=new Map<String, Integer>(); //for each contact the CountNumber

if(trigger.isinsert){
List<Lent__c> counts =[select Contact__c, Contact__r.Count__c
from Lent__c where id IN :Trigger.new FOR UPDATE];
for(Lent__c lent:counts){
contact_newCount_Map.put(lent.Contact__c, Integer.valueOf(lent.Contact__r.Count__c==null ? 0 : lent.Contact__r.Count__c) + 1);
}
}
else{
Set<Id> contactIds = new Set<Id>();
for (Lent__c l : Trigger.old)
contactIds.add(l.Contact__c);
Map<Id,Contact> oldContacts = new Map<Id,Contact>([SELECT Count__c From Contact where Id IN :contactIds]);
for (Lent__c lent : counts)
contact_newCount_map.put(lent.Contact__c, Integer.valueOf(oldContacts.get(lent.Contact__c).Count__c == null ? 0 : oldContacts.get(lent.Contact__c).Count__c ) -1);
}
}
for(Contact con : [select id, Count__c from Contact WHERE ID IN : contact_newCount_Map.KeySet()]){ // line 21
con.Count__c=contact_newCount_Map.get(con.id);
counts_toUpdate.add(con);
}

update counts_toUpdate;
}

 

But I am getting Error: Compile Error: unexpected token: for line 21 column 0 at line 21

 

Please help.
virkvirk

Now there is another error as 

 

Error: Compile Error:  Variable does not exist: counts line 21 column 20

 

trigger UpdateCount on Lent__c (after insert,after delete) {
List<Contact> counts_toUpdate = new List<Contact>();
Map<String, Integer> contact_newCount_Map=new Map<String, Integer>(); //for each contact the CountNumber

if(trigger.isinsert){
List<Lent__c> counts =[select Contact__c, Contact__r.Count__c
from Lent__c where id IN :Trigger.new FOR UPDATE];
for(Lent__c lent:counts){
contact_newCount_Map.put(lent.Contact__c, Integer.valueOf(lent.Contact__r.Count__c==null ? 0 : lent.Contact__r.Count__c) + 1);
}
}
else{
Set<Id> contactIds = new Set<Id>();
for (Lent__c l : Trigger.old)
contactIds.add(l.Contact__c);
Map<Id,Contact> oldContacts = new Map<Id,Contact>([SELECT Count__c From Contact where Id IN :contactIds]);
for(Lent__c lent : counts)// line 17
contact_newCount_map.put(lent.Contact__c, Integer.valueOf(oldContacts.get(lent.Contact__c).Count__c == null ? 0 : oldContacts.get(lent.Contact__c).Count__c ) -1);
}

for(Contact con : [select id, Count__c from Contact WHERE ID IN : contact_newCount_Map.KeySet()]){
con.Count__c=contact_newCount_Map.get(con.id);
counts_toUpdate.add(con);
}

update counts_toUpdate;
}