Getting Object type of WhatId/WhoId Task/Event fields

[AdmiralRonton]

I'm looking to find the object types of the WhatId/WhoId fields of the Task and Event objects, so I can query these objects and get more information about them and perform certain automated tasks based on the type.

I found this tech article, which uses the first 3 digits as a marker, but the article also says that this may change at any time:

http://www.sforce.com/us/resources/tn-1.jsp

Is there a better way of getting the object types of WhatId/WhoId fields or querying them based on Id only (no type)?

Thanks!

[DevAngel]

Hi AdmiralRonton,

The only option available at this time is the one presented in the tech note.

[iperez_genius]

can i ask...
if i am looking to find out if a task belongs to a lead or a contact how exactly to i code that...
?

[vchaddha]

Well i found something a User poited out on ideas, HE SAID:

"[Select Who.name from task where id = :taskid];

Polymorphic relationships like who and what on task/event or owner on queue-ownable objects can be traversed. The object that is returned is called "Name". Here's the information you can access through this traversal:

(from the enterprise WSDL)
Alias
FirstName
LastName
Name
Type
UserRole
UserRoleId
"

But i could not understand how I could read these columns in APEX class?
My query is like this:
Select Subject,WhoId,WhatId,Who.FirstName,Who.Name,Who.type,What.type From task

Now i get a Collection NAME here which contains (FirstName,Name,Type), but how I could read these Values in APEX class? Any idea ?

[vanessen]

you can use prefixes like this:

String contact_prefix = Schema.SObjectType.Contact.getKeyPrefix();

for(Task t0 : trigger.new){

  if(((String)t0.WhoId).startsWith(case_prefix)){

  //do somerthing

  }

 }

enjoy it ....

[vchaddha]

Thanks. Yes that would also work.

[EMODULOR1]

what tech note are you referring to?  the URL in the previous post is dead... please let us know!!!

[SimonF]

The best way is to query for the type when you query for the Id, e.g.

select id, subject, who.id, who.type from Task

[EMODULOR1]

oh thanks, i ended up doing what another user posted and it worked!

if(ta.WhatId != null){

String account_prefix = Schema.SObjectType.Account.getKeyPrefix();

String task_whatid = ta.WhatId;

System.debug('who: ' + ta.WhoId + ' what: ' + ta.WhatId + ' prefix: ' + account_prefix + ' eval: ' + task_whatid.startsWith(account_prefix) + ' id: ' + ta.id );

if(task_whatid.startsWith(account_prefix)){