updating related list

Question

List<Opportunity> op = [
    SELECT Id,AccountId, External_Id__c, StageName, Sales_Office__c,
           Held_or_Purchased_Model_Lookup__c, Subdivision__c, Lot__c,
           Hold_Expiry_Date__c, Sales_Agent_Lookup__c, Real_Estate_Agent__c
    FROM Opportunity
    WHERE External_Id__c =: externalId
];

Purchased_Home__c purchasedHome = new Purchased_Home__c (
    Account_Name__c  = op.AccountId,                                                           
    External_ID__c  = op.External_Id__c,                                                                   
    Sales_Office__c  = op.Sales_Office__c,                                                                      
    Model__c  = op.Held_or_Purchased_Model_Lookup__c,                                                                       
    Subdivision__c = op.Subdivision__c,                                                                         
    Lot__c  = op.Lot__c,                                                                             
    Sales_Agent__c  = op.Sales_Agent_Lookup__c,                                                                                
    Real_Estate_Agent__c = op.Real_Estate_Agent__c                                                                               
    );

    insert purchasedHome;

code above works, but below doesn't work...

List <Co_Buyer__c> cobuyer = [
    SELECT First_Name__c, Last_Name__c, Home_Email__c, External_Id__c,Opportunity__c , Purchased_Home__c   
    FROM Co_Buyer__c where id =: op.id
];
for(Co_Buyer__c c : cobuyer){
    c.id = purchasedHome.Id;     
}
update cobuyer;

record of Purchased_Home__c is created from opportunity record, when certain conditions are met.

Co_Buyer__c is related list of op, and also needs to be created as purchasedhome's related list when purchasedHome record is created.

I'm having problem with related list part. When PurchasedHome record is created, cobuyers related list does not create with the purchased home record.

Thank you in advance.

Answer 1

I see few issues here.

1. You have the variable op declared as List<Opportunity> and that you are using it else here as op.Id, op.External_Id__c, which will not compile at first place as the variable is of type List. Assuming that is a typo and that you are using the first element from the list, say as op[0].Id, etc., your first part of code will work fine.

2. Your query of fetching the Co_Buyer__c is wrong. You have condition specified as Id = op.Id, which will never work. You need to specify the respective Opportunity field on the object on where clause to be able to fetch the record. The record’s Id will never match that to the Opportunity Id.

3. In the later part of your code, where you are trying to update the Co_Buyer__c records, you are trying this:

   c.id = purchasedHome.Id;
   

   which won't work because you are trying to update a record's Id field. You can never update a record's Id.

   I think you are trying to link this record to the newly created Purchased_Home__c record, in that scenario you need to use something as below, and then update the records.

   c.Purchased_Home__c = purchasedHome.Id;