Rapid Prototyping Tool

I'm looking for a tool that can create a rapid prototype (proof of concept) for an application, based on an existing PostgreSQL database. Something like Oracle Application Express, but for PostgreSQL, not the Oracle DBMS. Tool characteristics:

1. NO CODE ... ever, not even one line. The full application is created by one or more of these methods: (a) auto-generated by the tool based on the structure of the PostgreSQL database, (b) drag-and-drop of tool-supplied icons in a screen builder window, and (c) fill in the blanks of a property sheet for each generated screen component.
2. Portable: runs on all platforms where PostgreSQL runs.
3. The generated proof of concept (prototype) respects Referential Integrity as declared in the database design.

Since #1 and #3 existed in 1968 (see "Query by Example"), I'm hoping the world hasn't fallen too far behind in the intervening 47 years.

TIA,

Mark