Ecto Thinking

Mental shifts for Ecto and data layer design. These insights challenge typical ORM patterns.

Context = Setting That Changes Meaning

Context isn't just a namespace—it changes what words mean. "Product" means different things in Checkout (SKU, name), Billing (SKU, cost), and Fulfillment (SKU, warehouse). Each bounded context may have its OWN Product schema/table.

Think top-down: Subdomain → Context → Entity. Not "What context does Product belong to?" but "What is a Product in this business domain?"

Cross-Context References: IDs, Not Associations

schema "cart_items" do
  field :product_id, :integer  # Reference by ID
  # NOT: belongs_to :product, Catalog.Product
end