Foreign Constraint Error/Race Condition on TeamUser Projection

[bponghneng]

Description

The user registration workflow triggers the UserRegistered process manager, which creates a user, creates a team and then adds the user to the team. All three have read model projections. The TeamUser projection may attempt to project a team user association before the Team and User projections have finished, which causes a foreign constraint error.

Steps to Reproduce

Run mix test for the following files which test the user registration workflow:

• test/reply_express_web/controllers/api/v1/users/registration_controller_test.exs
• test/reply_express/accounts/users_context_test.exs
• test/reply_express/accounts/users_context_test.exs

Recommended Solution

See usage of the error/2 callback on the Elixir Commanded.Projections.Ecto package and Commanded.Event.Handler package. Introduce a retry after delay:

• https://hexdocs.pm/commanded_ecto_projections/usage.html#error-handling
• https://hexdocs.pm/commanded/Commanded.Event.Handler.html#c:error/3

[google-labs-jules]

Jules is on it. When finished, you will see another comment and be able to review a PR.