sqlalchemy/test/sql/test_lateral.py

from sqlalchemy import Column
from sqlalchemy import column
from sqlalchemy import ForeignKey
from sqlalchemy import Integer
from sqlalchemy import join
from sqlalchemy import lateral
from sqlalchemy import String
from sqlalchemy import Table
from sqlalchemy import table
from sqlalchemy import true
from sqlalchemy.engine import default
from sqlalchemy.sql import func
from sqlalchemy.sql import select
from sqlalchemy.sql.selectable import Lateral
from sqlalchemy.testing import assert_raises_message
from sqlalchemy.testing import AssertsCompiledSQL
from sqlalchemy.testing import fixtures


class LateralTest(fixtures.TablesTest, AssertsCompiledSQL):
    __dialect__ = default.DefaultDialect(supports_native_boolean=True)

    run_setup_bind = None

    run_create_tables = None

    @classmethod
    def define_tables(cls, metadata):
        Table(
            "people",
            metadata,
            Column("people_id", Integer, primary_key=True),
            Column("age", Integer),
            Column("name", String(30)),
        )
        Table(
            "bookcases",
            metadata,
            Column("bookcase_id", Integer, primary_key=True),
            Column(
                "bookcase_owner_id", Integer, ForeignKey("people.people_id")
            ),
            Column("bookcase_shelves", Integer),
            Column("bookcase_width", Integer),
        )
        Table(
            "books",
            metadata,
            Column("book_id", Integer, primary_key=True),
            Column(
                "bookcase_id", Integer, ForeignKey("bookcases.bookcase_id")
            ),
            Column("book_owner_id", Integer, ForeignKey("people.people_id")),
            Column("book_weight", Integer),
        )

    def test_standalone(self):
        table1 = self.tables.people
        subq = select([table1.c.people_id])

        # alias name is not rendered because subquery is not
        # in the context of a FROM clause
        self.assert_compile(
            lateral(subq, name="alias"),
            "LATERAL (SELECT people.people_id FROM people)",
        )

        self.assert_compile(
            subq.lateral(name="alias"),
            "LATERAL (SELECT people.people_id FROM people)",
        )

    def test_select_from(self):
        table1 = self.tables.people
        subq = select([table1.c.people_id])

        # in a FROM context, now you get "AS alias" and column labeling
        self.assert_compile(
            select([subq.lateral(name="alias")]),
            "SELECT alias.people_id FROM LATERAL "
            "(SELECT people.people_id AS people_id FROM people) AS alias",
        )

    def test_plain_join(self):
        table1 = self.tables.people
        table2 = self.tables.books
        subq = select([table2.c.book_id]).where(
            table2.c.book_owner_id == table1.c.people_id
        )

        # FROM books, people?  isn't this wrong?  No!  Because
        # this is only a fragment, books isn't in any other FROM clause
        self.assert_compile(
            join(table1, lateral(subq, name="alias"), true()),
            "people JOIN LATERAL (SELECT books.book_id AS book_id "
            "FROM books, people WHERE books.book_owner_id = people.people_id) "
            "AS alias ON true",
        )

        # put it in correct context, implicit correlation works fine
        self.assert_compile(
            select([table1]).select_from(
                join(table1, lateral(subq, name="alias"), true())
            ),
            "SELECT people.people_id, people.age, people.name "
            "FROM people JOIN LATERAL (SELECT books.book_id AS book_id "
            "FROM books WHERE books.book_owner_id = people.people_id) "
            "AS alias ON true",
        )

        # explicit correlation
        subq = subq.correlate(table1)
        self.assert_compile(
            select([table1]).select_from(
                join(table1, lateral(subq, name="alias"), true())
            ),
            "SELECT people.people_id, people.age, people.name "
            "FROM people JOIN LATERAL (SELECT books.book_id AS book_id "
            "FROM books WHERE books.book_owner_id = people.people_id) "
            "AS alias ON true",
        )

    def test_join_lateral_w_select_subquery(self):
        table1 = self.tables.people
        table2 = self.tables.books

        subq = (
            select([table2.c.book_id])
            .correlate(table1)
            .where(table1.c.people_id == table2.c.book_owner_id)
            .lateral()
        )
        stmt = select([table1, subq.c.book_id]).select_from(
            table1.join(subq, true())
        )

        self.assert_compile(
            stmt,
            "SELECT people.people_id, people.age, people.name, anon_1.book_id "
            "FROM people JOIN LATERAL (SELECT books.book_id AS book_id "
            "FROM books "
            "WHERE people.people_id = books.book_owner_id) AS anon_1 ON true",
        )

    def test_from_function(self):
        bookcases = self.tables.bookcases
        srf = lateral(func.generate_series(1, bookcases.c.bookcase_shelves))

        self.assert_compile(
            select([bookcases]).select_from(bookcases.join(srf, true())),
            "SELECT bookcases.bookcase_id, bookcases.bookcase_owner_id, "
            "bookcases.bookcase_shelves, bookcases.bookcase_width "
            "FROM bookcases JOIN "
            "LATERAL generate_series(:generate_series_1, "
            "bookcases.bookcase_shelves) AS anon_1 ON true",
        )

    def test_no_alias_construct(self):
        a = table("a", column("x"))

        assert_raises_message(
            NotImplementedError,
            "The Lateral class is not intended to be constructed directly.  "
            r"Please use the lateral\(\) standalone",
            Lateral,
            a,
            "foo",
        )