JSON foreign keys in PostgreSQL

Question

Is it possible to assign a foreign key to a json property in PostgreSQL? Here is an example what I would like to achieve, but it doesn\'t work:

CREATE TABLE User         


        

Answer 1

Here's a little SPI function have_ids which I use for an integrity constraint on a one-to-many relationship with a jsonb column

CREATE TABLE foo (
  id INTEGER NOT NULL
)

CREATE TABLE bar (
  foo_ids pg_catalog.jsonb DEFAULT '[]'::jsonb NOT NULL,
  CONSTRAINT bar_fooids_chk CHECK (have_ids ('foo', foo_ids))
)

With a couple of triggers on foo it's almost as good as a foreign key.