feat: computed column to verify unique value in form change

schema/deploy/computed_columns/form_change_is_unique_value.sql

@@ -0,0 +1,28 @@
+-- Deploy cif:computed_columns/form_change_is_unique_value to pg
+
+begin;
+
+create or replace function cif.form_change_is_unique_value(fc cif.form_change, column_name text) returns boolean as
+$computed_column$
+declare
+  retVal boolean;
+begin
+  execute format(
+    '
+    select not exists(
+      select 1
+      from %s.%s
+      where %s = $1
+      and archived_at is null
+    )
+    ',
+    quote_ident(fc.form_data_schema_name),
+    quote_ident(fc.form_data_table_name),
+    quote_ident(cif_private.camel_to_snake_case(column_name))
+  ) using jsonb_extract_path_text(fc.new_form_data, column_name) into retVal;
+  return retVal;
+end;
+$computed_column$ language plpgsql stable;
+
+
+commit;

schema/revert/computed_columns/form_change_is_unique_value.sql

@@ -0,0 +1,7 @@
+-- Revert cif:computed_columns/form_change_is_unique_value from pg
+
+begin;
+
+drop function cif.form_change_is_unique_value(cif.form_change, text);
+
+commit;

schema/sqitch.plan

@@ -61,3 +61,4 @@ computed_columns/operator_pending_form_change 2022-02-16T21:48:38Z Pierre Bastia
 functions/pending_new_form_change_for_table 2022-03-05T00:09:42Z Pierre Bastianelli <pierre.bastianelli@gov.bc.ca> # a custom query that returns a pending form change for the current user for a given table name. Allows to resume an object creation
 mutations/create_project_revision 2022-02-24T19:17:45Z Matthieu Foucault <matthieu@button.is> # add function to create a project revision for a given project
 computed_columns/project_revision_project_contact_form_changes 2022-03-03T17:16:01Z Matthieu Foucault <matthieu@button.is> # add a computed column to return a project_revision's contact form_change
+computed_columns/form_change_is_unique_value 2022-03-11T22:54:06Z Pierre Bastianelli <pierre.bastianelli@gov.bc.ca> # A computed column that returns whether a column name already has a value in the database

schema/test/unit/computed_columns/form_change_is_unique_value_test.sql

@@ -0,0 +1,66 @@
+
+
+begin;
+
+select plan(4);
+
+create table cif.test_table(
+  id integer primary key generated always as identity,
+  test_field text,
+  archived_at timestamptz
+);
+
+insert into cif.form_change(new_form_data, operation, form_data_schema_name, form_data_table_name, change_reason, json_schema_name)
+values (
+  '{"testField": "test value"}',
+  'create',
+  'cif',
+  'test_table',
+  'form_change_is_unique_value test',
+  'schema'
+);
+
+
+select is(
+  (
+    select cif.form_change_is_unique_value((select row(form_change.*)::cif.form_change from cif.form_change where change_reason='form_change_is_unique_value test'), 'testField')
+  ),
+  true,
+  'Returns true if the table is empty'
+);
+
+insert into cif.test_table(test_field)
+values ('another value');
+
+select is(
+  (
+    select cif.form_change_is_unique_value((select row(form_change.*)::cif.form_change from cif.form_change where change_reason='form_change_is_unique_value test'), 'testField')
+  ),
+  true,
+  'Returns true if the table does not contain the value'
+);
+
+insert into cif.test_table(test_field)
+values ('test value');
+
+select is(
+  (
+    select cif.form_change_is_unique_value((select row(form_change.*)::cif.form_change from cif.form_change where change_reason='form_change_is_unique_value test'), 'testField')
+  ),
+  false,
+  'Returns false if the value exists in the table'
+);
+
+update cif.test_table set archived_at=now() where test_field='test value';
+
+select is(
+  (
+    select cif.form_change_is_unique_value((select row(form_change.*)::cif.form_change from cif.form_change where change_reason='form_change_is_unique_value test'), 'testField')
+  ),
+  true,
+  'Returns true if the value exists in the table on a record that is archived'
+);
+
+select finish();
+
+rollback;

schema/verify/computed_columns/form_change_is_unique_value.sql

@@ -0,0 +1,7 @@
+-- Verify cif:computed_columns/form_change_is_unique_value on pg
+
+begin;
+
+select pg_get_functiondef('cif.form_change_is_unique_value(cif.form_change, text)'::regprocedure);
+
+rollback;