How do I add fields to an existing custom entity? (repost)
115250
How do I add fields to an existing custom entity?
149921
Can we insert or update FieldSets using apex code?
97420
How to programmatically create Fields?
140059
How do I alter the entity type class?
151115
Programmatically create an entity
5646
Updating a field programmatically, hook_node_update
30072
Extending the User model with custom fields in Django
143447
Programmatically add a taxonomy term as entity reference in a custom entity
39974
How can I programmatically add members to a group?
29904
Why can't I see related data in my Apex, or why are related records showing up as `null`?
66103
Any way to retrieve the CreatedDate of a CustomField via Apex?
106367
How to add a default item to a custom taxonomy?
131964
How to display the field history related list for a custom object on a Visualforce page?
136254
Custom Settings and fields
80688
How do I add custom properties to a form
68222
Reference to undeclared entity exception while working with XML
75169
Creating master-detail pages for entities, how to link them and which bean scope to choose