Create multiple tables in same time on RethinkDB

Question

I wrote a little script to create DB and some tables inside a RethinkDB if database don't exist.

I'm using the Python shell to communicate with RethinkDB

import rethinkdb as r

r.connect('localhost', 28015).repl()

r.db_list().contains('atlas').do(lambda databaseExists:
    r.branch(
        databaseExists,
        { 'dbs_created': 0 },
        r.db_create('atlas'),
        r.db('atlas').table_create('Carts'),
        r.db('atlas').table_create('Checkouts'),
        r.db('atlas').table_create('Collections'),
        r.db('atlas').table_create('Contents'),
        r.db('atlas').table_create('Orders'),
        r.db('atlas').table_create('Products'),
        r.db('atlas').table_create('Users'),
        r.db('atlas').table('Users').filter({'email': '{[email protected]}'}).update({'status': 'active', 'scope': ['admin']})
    )
).run()

exit()

This work well and create database if not exist but it create only the first table Carts and skip the next request.

I tried with this instead

r.expr(['Carts', 'Checkouts', 'Collections', 'Contents', 'Orders', 'Products', 'Users']).do(lambda tables:
    for table in tables:
        r.db('atlas').table_create(table)
),

But I get an invalid syntax error

File "<stdin>", line 10
    r.expr(['Carts', 'Checkouts', 'Collections', 'Contents', 'Orders', 'Products', 'Users']).do(for table in tables:
                                                                                                  ^
 SyntaxError: invalid syntax

How can I create all this tables once instead only the first table ?

Answer 1

In your first query, you pass 11 arguments to branch. The behaviour of

r.branch(A, B, C, D, E, F, G)

it behaves like

if A:
  return B
elif C:
  return D
elif E:
  return F
else:
  return G

In your second query, you use for ... in .... This Python construct is not legal as the body of a lambda. It also does not work inside ReQL queries.

A useful way of combining write operations in a single RethinkDB query is to use for_each. Here is an example:

r.branch(
  r.db_list().contains('atlas'),
  { 'dbs_created': 0 },
  r.expr([
    r.db_create('atlas'),
    r.db('atlas').table_create('Carts'),
    r.db('atlas').table_create('Checkouts')
  ]).for_each(x => x))