"Who knows who" relations in Salesforce Contact and Accounts - part 2: Solution description

"Who Knows Who" - insert, update and delete reverse records

"Who Knows Who" custom object has Master-Detail relation with "reverse" record which inserts after insertion first record. When "Who Knows Who" record inserted, fires trigger which inserts "reverse" record:

 if(trigger.IsInsert){        
      for(Linked_Relationship__c l: trigger.new){
          if(l.Master_Relationship__c == null && l.Firm__c != l.Related_To_Firm__c){
               Linked_Relationship__c lc = new Linked_Relationship__c();
               lc.Firm__c =  l.Related_To_Firm__c;
               lc.Contact__c =    l.Related_To_Contact__c;
               lc.Related_To_Contact__c = l.Contact__c;
               lc.Related_To_Firm__c = l.Firm__c;
               lc.Reverse_Type__c =   l.Type__c;
               lc.Type__c = l.Reverse_Type__c;
               lc.Comments__c = l.Comments__c;
               lc.Master_Relationship__c = l.id;
               lc.Reverse_Contact_Relationship__c = l.Contact_Relationship__c; 
               lc.Contact_Relationship__c = l.Reverse_Contact_Relationship__c;
               toInsert.Add(lc); 
           }            
       }                                                    
   }

After "Who Knows Who" record update "reverse" record also will be updated (no difference - master or detail):

if(trigger.IsUpdate){        
     for(Linked_Relationship__c lr : trigger.new){
         if(lr.Master_Relationship__c == null){
              lrIds.Add(lr.Id);
         }
         else{
              masterIds.Add(lr.Master_Relationship__c);
         }
     }
     List updateList = [SELECT Id, Firm__c, Contact__c, Related_To_Contact__c, Related_To_Firm__c,
                                                  Reverse_Type__c, Type__c, Comments__c, Master_Relationship__c, 
                                                  Reverse_Contact_Relationship__c, Contact_Relationship__c
                                                  FROM Linked_Relationship__c WHERE
                                                  Master_Relationship__c IN: lrIds OR Id IN: masterIds];
    for(Linked_Relationship__c l : updateList ){
       if(l.Master_Relationship__c != null){
            lrMap.put(l.Master_Relationship__c, l);
       }
       else{
            lrMap.put(l.Id, l);  
       }
   }

   for(Linked_Relationship__c lr : trigger.new){
        if(lrMap.containskey(lr.Id)) {
            if (!(lrMap.get(lr.Id).Firm__c==lr.Related_To_Firm__c&&lrMap.get(lr.Id).Related_To_Firm__c==lr.Firm__c&&lrMap.get(lr.Id).Related_To_Contact__c==lr.Contact__c&&lrMap.get(lr.Id).Contact__c==lr.Related_To_Contact__c&&lrMap.get(lr.Id).Type__c==lr.Reverse_Type__c&&lrMap.get(lr.Id).Reverse_Type__c==lr.Type__c&&lrMap.get(lr.Id).Comments__c==lr.Comments__c&&lrMap.get(lr.Id).Reverse_Contact_Relationship__c == lr.Contact_Relationship__c&&lrMap.get(lr.Id).Contact_Relationship__c == lr.Reverse_Contact_Relationship__c )){
                lrMap.get(lr.Id).Firm__c =  lr.Related_To_Firm__c;
                lrMap.get(lr.Id).Contact__c = lr.Related_To_Contact__c;
                lrMap.get(lr.Id).Related_To_Contact__c = lr.Contact__c;
                lrMap.get(lr.Id).Related_To_Firm__c = lr.Firm__c;
                lrMap.get(lr.Id).Reverse_Type__c =   lr.Type__c;
                lrMap.get(lr.Id).Type__c = lr.Reverse_Type__c;
                lrMap.get(lr.Id).Comments__c = lr.Comments__c;
                lrMap.get(lr.Id).Reverse_Contact_Relationship__c = lr.Contact_Relationship__c; 
                lrMap.get(lr.Id).Contact_Relationship__c = lr.Reverse_Contact_Relationship__c;
                toInsert.Add(lrMap.get(lr.Id));
            }   
        }
       if(lrMap.containskey(lr.Master_Relationship__c)){ 
           if(!(lrMap.get(lr.Master_Relationship__c).Firm__c==lr.Related_To_Firm__c&&lrMap.get(lr.Master_Relationship__c).Related_To_Firm__c==lr.Firm__c&&lrMap.get(lr.Master_Relationship__c).Related_To_Contact__c==lr.Contact__c&&lrMap.get(lr.Master_Relationship__c).Contact__c==lr.Related_To_Contact__c&&lrMap.get(lr.Master_Relationship__c).Type__c==lr.Reverse_Type__c&&lrMap.get(lr.Master_Relationship__c).Reverse_Type__c==lr.Type__c&&lrMap.get(lr.Master_Relationship__c).Comments__c==lr.Comments__c&&lrMap.get(lr.Master_Relationship__c).Reverse_Contact_Relationship__c == lr.Contact_Relationship__c&&lrMap.get(lr.Master_Relationship__c).Contact_Relationship__c == lr.Reverse_Contact_Relationship__c )){
                lrMap.get(lr.Master_Relationship__c).Firm__c =  lr.Related_To_Firm__c;
                lrMap.get(lr.Master_Relationship__c).Contact__c = lr.Related_To_Contact__c;
                lrMap.get(lr.Master_Relationship__c).Related_To_Contact__c = lr.Contact__c;
                lrMap.get(lr.Master_Relationship__c).Related_To_Firm__c = lr.Firm__c;
                lrMap.get(lr.Master_Relationship__c).Reverse_Type__c =   lr.Type__c;
                lrMap.get(lr.Master_Relationship__c).Type__c = lr.Reverse_Type__c;
                lrMap.get(lr.Master_Relationship__c).Comments__c = lr.Comments__c;
                lrMap.get(lr.Master_Relationship__c).Reverse_Contact_Relationship__c = lr.Contact_Relationship__c; 
                lrMap.get(lr.Master_Relationship__c).Contact_Relationship__c = lr.Reverse_Contact_Relationship__c;
                toInsert.Add(lrMap.get(lr.Master_Relationship__c));
           }       
       }                             
   }
}

If "Who Knows Who" record deleted, "reverse" record also will be deleted:

for(Linked_Relationship__c lr: trigger.old){                          
              lrMap.put(lr.Firm__c, lr);
        }
List lrList = [SELECT Id, Firm__c, Contact__c, Related_To_Contact__c, Related_To_Firm__c,
                                               Reverse_Type__c, Type__c, Comments__c,  Master_Relationship__c,
                                               Reverse_Contact_Relationship__c, Contact_Relationship__c
                                               FROM Linked_Relationship__c WHERE
                                               Related_To_Firm__c IN: lrMap.keySet() ];
for(Linked_Relationship__c l : lrList )  {
    if(lrMap.get(l.Related_To_Firm__c).Firm__c==l.Related_To_Firm__c&&lrMap.get(l.Related_To_Firm__c).Related_To_Firm__c==l.Firm__c&&lrMap.get(l.Related_To_Firm__c).Related_To_Contact__c==l.Contact__c && lrMap.get(l.Related_To_Firm__c).Contact__c==l.Related_To_Contact__c&&lrMap.get(l.Related_To_Firm__c).Reverse_Type__c==l.Type__c&&lrMap.get(l.Related_To_Firm__c).Type__c==l.Reverse_Type__c&&lrMap.get(l.Related_To_Firm__c).Contact_Relationship__c==l.Reverse_Contact_Relationship__c&&lrMap.get(l.Related_To_Firm__c).Reverse_Contact_Relationship__c==l.Contact_Relationship__c){
          toDelete.Add(l);
    }
}                                                                                                              
delete toDelete;

Trigger on Contact

When Contact record inserted, trigger insert "Who Knows Who" records("User knows Contact" scenario).

for(Contact c: trigger.new){                
     Linked_Relationship__c l = new Linked_Relationship__c();
     l.Firm__c = knowContList[0].AccountId;
     l.Contact__c = knowContList[0].Id;
     l.Related_To_Firm__c = c.AccountId;
     l.Related_To_Contact__c = c.Id;
     toInsert.Add(l);                       
   }                       
}

After insertion of the first record, trigger on "Who Knows Who" inserts second - reverse record.
After update of Contact - change Contact's Account, triggers updates related "Who Knows Who" records.

for(Contact c: trigger.new){
     if(c.AccountId != trigger.oldMap.get(c.Id).AccountId ){
        contIds.Add(c.id);
        Linked_Relationship__c l = new Linked_Relationship__c();
        l.Firm__c = c.AccountId;
        l.Related_To_Firm__c = c.AccountId;
        l.Related_To_Contact__c = c.Id;
        l.Reverse_Contact_Relationship__c = 'Employee';
        l.Type__c = 'Employer';
        toInsert.Add(l); 
    }
}
List l_oldList = [SELECT Id, Firm__c, Type__c, Comments__c, Contact_Relationship__c,
                                                      Related_To_Firm__c, Related_To_Contact__c, Reverse_Type__c, 
                                                      Reverse_Contact_Relationship__c, Contact__c FROM Linked_Relationship__c 
                                                      WHERE Related_To_Contact__c IN: contIds ];                                                                                                 

Map> lrMap = new Map>();
List otherList = new List();

for(Linked_Relationship__c lr : l_oldList ){
    if(lr.Reverse_Contact_Relationship__c != null && lr.Reverse_Contact_Relationship__c.contains('Employee')){
        if(lrMap.containskey(lr.Related_To_Contact__c)){
            lrMap.get(lr.Related_To_Contact__c).Add(lr);
        }
        else{
            lrMap.put(lr.Related_To_Contact__c, new List{lr});
        } 
     }
     else{
        otherList.Add(lr);
     }                       
}
for(Contact c: [SELECT Id, AccountId, Account.Name FROM Contact WHERE Id IN:  trigger.new]){
                 Linked_Relationship__c l_new = new Linked_Relationship__c();
                 if(!lrMap.containskey(c.Id)){
                     l_new.Firm__c = c.AccountId;
                     l_new.Reverse_Type__c = 'Former Employer';
                     l_new.Contact__c = c.Id;
                     l_new.Contact_Relationship__c = 'Former Employee';
                     l_new.Related_To_Firm__c = trigger.oldMap.get(c.Id).AccountId;
                     l_new.Comments__c = string.valueof(date.today()) + ' - ' + c.Account.Name ;
                     toInsert.Add(l_new);
                 }
                 else{
                     for(Linked_Relationship__c l_old : lrMap.get(c.Id)){
                         l_old.Type__c = 'Former Employer';                        
                         l_old.Reverse_Contact_Relationship__c = 'Former Employee';                     
                         l_old.Comments__c = string.valueof(date.today())+ ' - ' + c.Account.Name;                          
                         l_old.Related_To_Firm__c = c.AccountId;
                         l_old.Related_To_Contact__c = c.Id;                                                                                                                                                          
                         toInsert.Add(l_old);                         
                     }
                }
               for(Linked_Relationship__c l_other : otherList ){
                    if(l_other.Contact__c == c.Id){
                        l_other.Firm__c = c.AccountId;
                        l_other.Contact__c = c.Id;
                        toInsert.Add(l_other);
                    }
               }

If Contact deleted, all related "Who Knows Who" records also will be deleted.

for(Contact c: trigger.old){
     contIds.Add(c.Id);
}
List lrList = [SELECT Id, Related_To_Contact__c, Contact__c 
        FROM Linked_Relationship__c
        WHERE Contact__c IN: contIds OR Related_To_Contact__c IN: contIds];

if(lrList.size()>0){        
     delete lrList;
}