Entity and Field Considerations in Triggers | Force.com Apex Code Developer's Guide

QuestionDataCategorySelection Entity Not Available in After Insert Triggers

The after insert trigger that fires after inserting one or more Question records doesn’t have access to the QuestionDataCategorySelection records that are associated with the inserted Questions. For example, the following query doesn’t return any results in an after insert trigger:

1QuestionDataCategorySelection[] dcList = 
2    [select Id,DataCategoryName from QuestionDataCategorySelection where ParentId IN :questions];

Fields Not Updateable in Before Triggers

Some field values are set during the system save operation, which occurs after before triggers have fired. As a result, these fields cannot be modified or accurately detected in before insert or before update triggers. Some examples include:

Task.isClosed
Opportunity.amount*
Opportunity.ForecastCategory
Opportunity.isWon
Opportunity.isClosed
Contract.activatedDate
Contract.activatedById
Case.isClosed
Solution.isReviewed
Id (for all records)**
createdDate (for all records)**
lastUpdated (for all records)
Event.WhoId (when Shared Activities is enabled)
Task.WhoId (when Shared Activities is enabled)

* When Opportunity has no lineitems, Amount can be modified by a before trigger.

** Id and createdDate can be detected in before update triggers, but cannot be modified.

Fields Not Updateable in After Triggers

The following fields can’t be updated by after insert or after update triggers.

Event.WhoId
Task.WhoId

Considerations for Event DateTime Fields in Insert and Update Triggers

We recommend using the following date and time fields to create or update events.

When creating or updating a timed Event, use ActivityDateTime to avoid issues with inconsistent date and time values.
When creating or updating an all-day Event, use ActivityDate to avoid issues with inconsistent date and time values.
We recommend that you use DurationInMinutes because it works with all updates and creates for Events.

Operations Not Supported in Insert and Update Triggers

The following operations aren’t supported in insert and update triggers.

Manipulating an activity relation through the TaskRelation or EventRelation object, if Shared Activities is enabled
Manipulating an invitee relation on a group event through the Invitee object, whether or not Shared Activities is enabled

Entities Not Supported in Update Triggers

Certain objects can’t be updated, and therefore, shouldn’t have before update and after update triggers.

FeedItem
FeedComment

Entities Not Supported in After Undelete Triggers

Certain objects can’t be restored, and therefore, shouldn’t have after undelete triggers.

CollaborationGroup
CollaborationGroupMember
FeedItem
FeedComment

Considerations for Chatter Objects

Things to consider about FeedItem and FeedComment triggers:

Only FeedItems of Type TextPost, LinkPost, HasLink, ContentPost, and HasContent can be inserted, and therefore invoke the before or after insert trigger. User status updates don't cause the FeedItem triggers to fire.
While FeedPost objects were supported for API versions 18.0, 19.0, and 20.0, don't use any insert or delete triggers saved against versions prior to 21.0.
For FeedItem the following fields are not available in the before insert trigger:
- ContentSize
- ContentType
In addition, the ContentData field is not available in any delete trigger.
Triggers on FeedItem objects run before their attachment and capabilities information is saved, which means that ConnectApi.FeedItem.attachment information and ConnectApi.FeedElement.capabilities information may not be available in the trigger.
The attachment and capabilities information may not be available from these methods: ConnectApi.ChatterFeeds.getFeedItem, ConnectApi.ChatterFeeds.getFeedElement, ConnectApi.ChatterFeeds.getFeedPoll, ConnectApi.ChatterFeeds.getFeedElementPoll, ConnectApi.ChatterFeeds.postFeedItem, ConnectApi.ChatterFeeds.postFeedElement, ConnectApi.ChatterFeeds.shareFeedItem, ConnectApi.ChatterFeeds.shareFeedElement, ConnectApi.ChatterFeeds.voteOnFeedPoll, and ConnectApi.ChatterFeeds.voteOnFeedElementPoll
For FeedComment before insert and after insert triggers, the fields of a ContentVersion associated with the FeedComment (obtained through FeedComment.RelatedRecordId) are not available.
Apex code uses additional security when executing in a Chatter context. To post to a private group, the user running the code must be a member of that group. If the running user isn't a member, you can set the CreatedById field to be a member of the group in the FeedItem record.

Note the following for the CollaborationGroup and CollaborationGroupMember objects:

When CollaborationGroupMember is updated, CollaborationGroup is automatically updated as well to ensure that the member count is correct. As a result, when CollaborationGroupMember update or delete triggers run, CollaborationGroup update triggers run as well.

Considerations for the Salesforce Side Panel for Salesforce for Outlook

When an email is associated to a record using the Salesforce Side Panel for Salesforce for Outlook, the email associations are represented in the WhoId or WhatId fields on a task record. Associations are completed after the task is created, so the Task.WhoId and Task.WhatId fields aren’t immediately available in before or after Task triggers for insert and update events, and their values are initially null. The WhoId and WhatId fields are set on the saved task record in a subsequent operation, however, so their values can be retrieved later.