Enum types methods for postgresql

Author: enebo

lib/arjdbc/postgresql/adapter.rb

@@ -320,6 +320,38 @@ def extensions
       exec_query("SELECT extname FROM pg_extension", "SCHEMA").cast_values
     end
 
+    # Returns a list of defined enum types, and their values.
+    def enum_types
+      query = <<~SQL
+          SELECT
+            type.typname AS name,
+            string_agg(enum.enumlabel, ',' ORDER BY enum.enumsortorder) AS value
+          FROM pg_enum AS enum
+          JOIN pg_type AS type
+            ON (type.oid = enum.enumtypid)
+          GROUP BY type.typname;
+      SQL
+      exec_query(query, "SCHEMA").cast_values
+    end
+
+    # Given a name and an array of values, creates an enum type.
+    def create_enum(name, values)
+      sql_values = values.map { |s| "'#{s}'" }.join(", ")
+      query = <<~SQL
+          DO $$
+          BEGIN
+              IF NOT EXISTS (
+                SELECT 1 FROM pg_type t
+                WHERE t.typname = '#{name}'
+              ) THEN
+                  CREATE TYPE \"#{name}\" AS ENUM (#{sql_values});
+              END IF;
+          END
+          $$;
+      SQL
+      exec_query(query)
+    end
+
     # Returns the configured supported identifier length supported by PostgreSQL
     def max_identifier_length
       @max_identifier_length ||= query_value("SHOW max_identifier_length", "SCHEMA").to_i