Imrpove migrations

db/migrations/003_create_memberships.rb

@@ -0,0 +1,56 @@
+Sequel.migration do
+  up do
+    create_table(:memberships) do
+      primary_key :id, type: :Bignum
+
+      foreign_key :member_id, :members,
+        type: :Bignum,
+        null: false
+
+      String :status, null: false, default: "pending"
+
+      DateTime :requested_at,
+        null: false,
+        default: Sequel::CURRENT_TIMESTAMP
+
+      DateTime :decided_at
+
+      foreign_key :recorded_by, :members,
+        type: :Bignum
+
+      DateTime :ended_at
+      String :end_reason
+
+      index :status
+
+      # Un seul dossier en attente ou une seule adhésion
+      # en cours par adhérent.
+      index :member_id,
+        unique: true,
+        where: { status: ["pending", "accepted"], ended_at: nil }
+
+      constraint :memberships_status_valid,
+        Sequel.lit("status IN ('pending', 'accepted', 'rejected')")
+
+      constraint :memberships_decision_consistent,
+        Sequel.lit(
+          "(status = 'pending' AND decided_at IS NULL " \
+          "AND recorded_by IS NULL) " \
+          "OR (status IN ('accepted', 'rejected') " \
+          "AND decided_at IS NOT NULL AND recorded_by IS NOT NULL)"
+        )
+
+      constraint :memberships_end_consistent,
+        Sequel.lit(
+          "(ended_at IS NULL AND end_reason IS NULL) " \
+          "OR (status = 'accepted' AND ended_at IS NOT NULL " \
+          "AND end_reason IN ('resignation', 'death', " \
+          "'dissolution', 'exclusion'))"
+        )
+    end
+  end
+
+  down do
+    drop_table(:memberships)
+  end
+end