danini-the-panini · October 19, 2018 13:01 · Oct 19, 2018
diff --git a/rein_schema_dumper.rb b/rein_schema_dumper.rb
@@ -0,0 +1,43 @@
+module Rein::SchemaDumper
+  def tables(stream)
+    super
+    check_constraints(stream)
+  end
+
+  def check_constraints(stream)
+    constraints = @connection.execute <<-SQL
+      select *
+      from information_schema.check_constraints as c, information_schema.constraint_column_usage as u
+      where c.constraint_name = u.constraint_name
+        and c.constraint_schema = 'public'
+        and u.constraint_schema = 'public'
+    SQL
+
+    if constraints.any?
+      stream.puts
+    end
+
+    constraints.each do |constraint|
+      table_name = constraint['table_name']
+      column_name = constraint['column_name']
+      check_clause = constraint['check_clause']
+
+      case check_clause
+      when /#{column_name}\s+(>=|>|=|!=|<|<=)\s+(\d+)/
+        definition = case $1
+                     when '>=' then 'greater_than_or_equal_to'
+                     when '>'  then 'greater_than'
+                     when '<=' then 'less_than_or_equal_to'
+                     when '<'  then 'less_than'
+                     when '='  then 'equal_to'
+                     when '!=' then 'not_equal_to'
+                     end
+        stream.puts <<-RUBY
+  add_numericality_constraint "#{table_name}", "#{column_name}", #{definition}: #{$2}
+        RUBY
+      end
+    end
+  end
+end
+
+ActiveRecord::SchemaDumper.prepend Rein::SchemaDumper