Revert "Also remove Pg/SQL exception handling to avoid savepoints"

This reverts commit bd8c976.

Translation of exception messages depends on the aggregate id and type
to be known when an aggregate unique key is violated.

Author: erikrozendaal

db/migrate/20260220122600_sequent_avoid_exception_handling_in_update_unique_keys.rb

@@ -734,6 +734,10 @@ BEGIN
        SET key = EXCLUDED.key
      WHERE target.key <> EXCLUDED.key;
   END LOOP;
+EXCEPTION
+  WHEN unique_violation THEN
+    RAISE unique_violation
+    USING MESSAGE = 'duplicate unique key value for aggregate ' || (_aggregate->>'aggregate_type') || ' ' || _aggregate_id || ' (' || SQLERRM || ')';
 END;
 $$;
 
@@ -1584,7 +1588,6 @@ ALTER TABLE ONLY sequent_schema.snapshot_records
 SET search_path TO public,view_schema,sequent_schema;
 
 INSERT INTO "schema_migrations" (version) VALUES
-('20260220122600'),
 ('20260129130000'),
 ('20250815103000'),
 ('20250630113000'),

db/migrate/sequent/update_unique_keys_v04.sql

@@ -10,8 +10,24 @@
 module Sequent
   module Core
     class AggregateKeyNotUniqueError < RuntimeError
+      attr_reader :aggregate_type, :aggregate_id
+
       def self.unique_key_error_message?(message)
-        message =~ /duplicate key value violates unique constraint \"aggregate_unique_keys_scope_key_key\"/
+        message =~ /duplicate unique key value for aggregate/
+      end
+
+      def initialize(message)
+        super
+
+        match = message.match(
+          # rubocop:disable Layout/LineLength
+          /aggregate (\p{Upper}\p{Alnum}*(?:::\p{Upper}\p{Alnum}*)*) (\p{XDigit}{8}-\p{XDigit}{4}-\p{XDigit}{4}-\p{XDigit}{4}-\p{XDigit}{12})/,
+          # rubocop:enable Layout/LineLength
+        )
+        if match
+          @aggregate_type = match[1]
+          @aggregate_id = match[2]
+        end
       end
     end
 

db/structure.sql

@@ -545,8 +545,11 @@ def change_ssn(ssn)
 
         Sequent.aggregate_repository.add_aggregate(user_2)
 
-        expect { Sequent.aggregate_repository.commit(DummyCommand.new) }
-          .to raise_error(Sequent::Core::AggregateKeyNotUniqueError)
+        expect { Sequent.aggregate_repository.commit(DummyCommand.new) }.to raise_error(
+          an_instance_of(Sequent::Core::AggregateKeyNotUniqueError)
+            .and(having_attributes(message: /#{user_id_2}/))
+            .and(having_attributes(message: /DummyAggregateWithoutEmail/)),
+        )
       end
 
       it 'enforces key uniqueness with the same key scope across different aggregate types' do
@@ -568,7 +571,13 @@ def change_ssn(ssn)
 
         expect do
           Sequent.configuration.event_store.update_unique_keys([user_b.event_stream])
-        end.to raise_error(Sequent::Core::AggregateKeyNotUniqueError)
+        end.to raise_error(
+          an_instance_of(Sequent::Core::AggregateKeyNotUniqueError)
+            .and(having_attributes(message: /#{user_id_2}/))
+            .and(having_attributes(message: /DummyAggregateWithoutEmail/))
+            .and(having_attributes(aggregate_type: 'DummyAggregateWithoutEmail'))
+            .and(having_attributes(aggregate_id: user_id_2)),
+        )
       end
     end
   end

lib/sequent/core/event_store.rb

@@ -122,7 +122,11 @@ class UniqueKeysCommandHandler < Sequent::Core::BaseCommandHandler
         when_command UniqueKeysCommand.new(aggregate_id: aggregate_id_1, keys: %w[a])
         expect do
           when_command UniqueKeysCommand.new(aggregate_id: aggregate_id_2, keys: %w[a])
-        end.to raise_error(Sequent::Core::AggregateKeyNotUniqueError)
+        end.to raise_error(
+          an_instance_of(Sequent::Core::AggregateKeyNotUniqueError)
+            .and(having_attributes(aggregate_type: 'Sequent::Core::UniqueKeysAggregate'))
+            .and(having_attributes(aggregate_id: aggregate_id_2)),
+        )
       end
 
       context 'find by unique key' do