Get the underlying foreign key constrains based upon a view

Question

I have the following relations:

CREATE TABLE cities (
    city VARCHAR (80) PRIMARY KEY,
    LOCATION point
);

CREATE TABLE weather (
    city VARCHAR (80) REFERENCES cities (city),
    temp_lo INT,
    temp_hi INT,
    prcp REAL,
    DATE DATE
);

CREATE VIEW test AS SELECT
    *
FROM
    cities;

Now I would like to utilize the test view or any other view in a GUI which simply presents an editable table. This is possible with the recently introduced automatically updatable views. I want the table to contain drop-downs containing all possible values every time there is a column with constrains on it, like the column with a foreign key in this case.

How can this be achieved? I know that I could utilize enums and I do that today, but on Amazon RDS they are unreasonably hard to modify.

I had an idea of (ab)using the "EXPLAIN SELECT" query for each column and check which table and column is being queried.

Answer 1

You can check which tables are used by a view using this statement:

select vtu.table_schema, 
       vtu.table_name
from information_schema.view_table_usage vtu 
  join pg_class cl on cl.oid = (quote_ident(vtu.table_schema)||'.'||quote_ident(vtu.table_name))::regclass 
where (view_schema, view_name) = ('public', 'test');

If that returns only a single table, you can query the system for foreign keys referencing that (single) table.