[SalesForce] are Triggers (and their delegated classes) or Batch affected by sharing

  1. I understand with sharing classes run in User Mode, meaning they respect permissions, field-level security and sharing rules of the current user.

  2. I understand without sharing classes run in System Mode, and they ignore permissions, field-level security and sharing rules of the current user.

But I've noted that the relevant Salesforce docs say nothing about Triggers or the classes called inside them (which I understand to be in the same execution context as the record operations that fired them)

There's a post here that suggests "the trigger still runs in system context"
https://developer.salesforce.com/forums/ForumsMain?id=906F0000000904ZIAQ

What if I have a controller class without sharing doing DML causing a Trigger to be fired?

What if I have a controller class without sharing containing logic that starts a Batch job?

What I'm asking is, if (for example) the Site Guest User (a relatively unpowerful user in terms of sharing) causes a Trigger or Batch job to be fired, does that execution context have just as much clout as me causing it as a System Administrator from a Visualforce Page?

Best Answer

The system context is not just about sharing. From the docs:

In system context, Apex code has access to all objects and fields— object permissions, field-level security, sharing rules aren’t applied for the current user.

setting a class to run "with sharing" tells Apex to apply the current sharing rules for the current user, but field level security, object permissions etc still don't get applied. The class doesn't run in user mode though - only standard controllers or code run via execute anonymous run in user mode.

If you have a controller class without sharing that causes a trigger to be fired, the trigger will still run in the system context (i.e. no sharing, FLS, object security). If you need to respect sharing your trigger will need to delegate to a class declared as 'with sharing'.

There's a blog post from Abhinav Gupta that covers some of this, although its coming from the other side and explaining how delegating to a 'with sharing' class takes a trigger out of full system context:

http://www.tgerm.com/2011/03/trigger-insufficient-access-cross.html

Guest site user is a slightly different situation, in that some of its ability to access objects is constrained by the user license. I've hit the issue where I was trying to update something that the guest user profile should only have read/create permission on, so I thought I'd get around it using a custom controller (running in the system context). This had worked for me for contacts, but for another standard object I received an error that the license didn't support the operation. The license issue persisted even if I executed the update from an @future method. So no, I wouldn't expect it to have as much clout as the system administrator, although actions that should be prohibited by the license may sometimes work.

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