checker.rb in strong_migrations-0.6.8

- old
+ new

@@ -194,16 +194,30 @@
           raise_error :execute, header: "Possibly dangerous operation"
         when :change_column_null
           table, column, null, default = args
           if !null
             if postgresql?
-              # match https://github.com/nullobject/rein
-              constraint_name = "#{table}_#{column}_null"
+              safe = false
+              if postgresql_version >= Gem::Version.new("12")
+                # TODO likely need to quote the column in some situations
+                safe = constraints(table).any? { |c| c["def"] == "CHECK ((#{column} IS NOT NULL))" }
+              end
 
-              raise_error :change_column_null_postgresql,
-                add_constraint_code: constraint_str("ALTER TABLE %s ADD CONSTRAINT %s CHECK (%s IS NOT NULL) NOT VALID", [table, constraint_name, column]),
-                validate_constraint_code: constraint_str("ALTER TABLE %s VALIDATE CONSTRAINT %s", [table, constraint_name])
+              unless safe
+                # match https://github.com/nullobject/rein
+                constraint_name = "#{table}_#{column}_null"
+
+                validate_constraint_code = String.new(constraint_str("ALTER TABLE %s VALIDATE CONSTRAINT %s", [table, constraint_name]))
+                if postgresql_version >= Gem::Version.new("12")
+                  validate_constraint_code << "\n    #{command_str(:change_column_null, [table, column, null])}"
+                  validate_constraint_code << "\n    #{constraint_str("ALTER TABLE %s DROP CONSTRAINT %s", [table, constraint_name])}"
+                end
+
+                raise_error :change_column_null_postgresql,
+                  add_constraint_code: constraint_str("ALTER TABLE %s ADD CONSTRAINT %s CHECK (%s IS NOT NULL) NOT VALID", [table, constraint_name, column]),
+                  validate_constraint_code: validate_constraint_code
+              end
             elsif mysql? || mariadb?
               raise_error :change_column_null_mysql
             elsif !default.nil?
               raise_error :change_column_null,
                 code: backfill_code(table, column, default)
@@ -253,11 +267,10 @@
       end
 
       result
     end
 
-    # TODO allow string timeouts in 0.7.0
     def set_timeouts
       if !@timeouts_set
         if StrongMigrations.statement_timeout
           statement =
             if postgresql?
@@ -377,20 +390,20 @@
       end
     end
 
     # units: https://www.postgresql.org/docs/current/config-setting.html
     def timeout_to_sec(timeout)
-      suffixes = {
+      units = {
         "us" => 0.001,
         "ms" => 1,
         "s" => 1000,
         "min" => 1000 * 60,
         "h" => 1000 * 60 * 60,
         "d" => 1000 * 60 * 60 * 24
       }
       timeout_ms = timeout.to_i
-      suffixes.each do |k, v|
+      units.each do |k, v|
         if timeout.end_with?(k)
           timeout_ms *= v
           break
         end
       end
@@ -401,9 +414,19 @@
       if timeout.is_a?(String)
         timeout
       else
         timeout.to_i * 1000
       end
+    end
+
+    def constraints(table_name)
+      query = <<-SQL
+        SELECT conname AS name, pg_get_constraintdef(oid) AS def FROM pg_constraint
+        WHERE contype = 'c'
+          AND convalidated
+          AND conrelid = #{connection.quote(connection.quote_table_name(table_name))}::regclass
+      SQL
+      connection.select_all(query.squish).to_a
     end
 
     def raise_error(message_key, header: nil, append: nil, **vars)
       return unless StrongMigrations.check_enabled?(message_key, version: version)
 