fix: clean up pacticipants with no names

db/migrations/20220625_delete_pacticipants_with_no_name.rb

@@ -0,0 +1,62 @@
+# There was a bug that caused a duplicate pacticipant to be created
+# with a null name when updating the pacticipant in a certain way.
+# It was fixed in be24a8ad650f0ed49993283b22ba1d1a744fb3e8.
+# This migration deletes any pacticipants with null names that are not referenced by any other rows,
+# or assigns a name if the pacticipant is referenced so that it can be deleted through the API
+# (I can't think of a reason why a pacticipant with a null name should be referenced, but better to be safe than sorry).
+# The "find tables that reference pacticipants" logic is done dynamically because Pactflow has extra tables not in the OSS.
+
+# Query each table that references the pacticipants table to determine
+# if there are any rows in it that reference the pacticipant with the specified ID.
+# @return [Boolean]
+def pacticipant_is_unreferenced(pacticipant_id, table_foreign_keys)
+  table_foreign_keys.any? do | (table_name, foreign_keys) |
+    criteria = foreign_keys.flat_map do | fk |
+      fk[:columns].collect do | column_name |
+        { column_name => pacticipant_id }
+      end
+    end
+
+    # SELECT 'one' FROM xxx where consumer_id = x or provider_id = x LIMIT 1
+    !from(table_name).where(Sequel.|(*criteria)).empty?
+  end
+end
+
+# Return a structure describing the tables and columns that reference the pacticipants table.
+# @return [Array] eg. [ [:integrations, [ { columns: [:consumer_id] }, { columns: [:provider_id] } ] ] ]
+def get_table_foreign_keys
+  table_foreign_keys = tables.sort.collect do | table_name |
+    key_list = foreign_key_list(table_name).select{ |fk| fk[:table] == :pacticipants }
+    if key_list.any?
+      [ table_name,  key_list]
+    end
+  end.compact
+
+  # move the integrations table check first because that's the most likely candidate to have a referencing row
+  table_foreign_keys.select{ |(table_name, _)| table_name == :integrations } | table_foreign_keys
+end
+
+# Deletes the pacticipant if it is unreferenced, or populates the name so it can
+# be deleted through the API.
+def delete_pacticipant_or_populate_name(row, table_foreign_keys)
+  if pacticipant_is_unreferenced(row[:id], table_foreign_keys)
+    from(:pacticipants).where(id: row[:id]).delete
+  else
+    from(:pacticipants).where(id: row[:id]).update(name: "Delete me #{row[:id]}")
+  end
+end
+
+Sequel.migration do
+  up do
+
+    table_foreign_keys = get_table_foreign_keys
+
+    from(:pacticipants).where(name: nil).all.each do | row |
+      delete_pacticipant_or_populate_name(row, table_foreign_keys)
+    end
+  end
+
+  down do
+
+  end
+end

spec/migrations/20220625_delete_pacticipants_with_no_name_spec.rb

@@ -0,0 +1,20 @@
+describe "deleting unreferenced pacticipants with no name", migration: true do
+  before do
+    PactBroker::Database.migrate(20220622)
+  end
+
+  let(:now) { DateTime.new(2017, 1, 1) }
+  let!(:has_name) { create(:pacticipants, { name: "aaa", created_at: now, updated_at: now }) }
+  let!(:no_name_1) { create(:pacticipants, { created_at: now, updated_at: now }) }
+  let!(:no_name_2) { create(:pacticipants, { created_at: now, updated_at: now }) }
+
+  let!(:integration) { create(:integrations, { consumer_id: has_name[:id], provider_id: no_name_1[:id], created_at: now }) }
+
+  it "deletes the pacticipant with no name that has no other rows referencing it" do
+    expect(database[:pacticipants].count).to eq 3
+    expect(database[:pacticipants].where(name: nil).count).to eq 2
+    PactBroker::Database.migrate(20220625)
+    expect(database[:pacticipants].where(name: nil).count).to eq 0
+    expect(database[:pacticipants].count).to eq 2
+  end
+end