sqlalchemy/test/sql/test_computed.py

# coding: utf-8
from sqlalchemy import Column
from sqlalchemy import Computed
from sqlalchemy import Integer
from sqlalchemy import MetaData
from sqlalchemy import Table
from sqlalchemy.exc import ArgumentError
from sqlalchemy.schema import CreateTable
from sqlalchemy.testing import assert_raises_message
from sqlalchemy.testing import AssertsCompiledSQL
from sqlalchemy.testing import combinations
from sqlalchemy.testing import fixtures
from sqlalchemy.testing import is_
from sqlalchemy.testing import is_not


class DDLComputedTest(fixtures.TestBase, AssertsCompiledSQL):
    __dialect__ = "default"

    @combinations(
        ("no_persisted", "", "ignore"),
        ("persisted_none", "", None),
        ("persisted_true", " STORED", True),
        ("persisted_false", " VIRTUAL", False),
        id_="iaa",
    )
    def test_column_computed(self, text, persisted):
        m = MetaData()
        kwargs = {"persisted": persisted} if persisted != "ignore" else {}
        t = Table(
            "t",
            m,
            Column("x", Integer),
            Column("y", Integer, Computed("x + 2", **kwargs)),
        )
        self.assert_compile(
            CreateTable(t),
            "CREATE TABLE t (x INTEGER, y INTEGER GENERATED "
            "ALWAYS AS (x + 2)%s)" % text,
        )

    def test_other_options(self):
        t = Table(
            "t",
            MetaData(),
            Column(
                "y", Integer, Computed("x + 2"), nullable=False, unique=True
            ),
        )
        self.assert_compile(
            CreateTable(t),
            "CREATE TABLE t ("
            "y INTEGER GENERATED ALWAYS AS (x + 2) NOT NULL, UNIQUE (y))",
        )

    def test_server_default_onupdate(self):
        text = (
            "A generated column cannot specify a server_default or a "
            "server_onupdate argument"
        )

        def fn(**kwargs):
            m = MetaData()
            Table(
                "t",
                m,
                Column("x", Integer),
                Column("y", Integer, Computed("x + 2"), **kwargs),
            )

        assert_raises_message(ArgumentError, text, fn, server_default="42")
        assert_raises_message(ArgumentError, text, fn, server_onupdate="42")

    def test_to_metadata(self):
        comp1 = Computed("x + 2")
        m = MetaData()
        t = Table("t", m, Column("x", Integer), Column("y", Integer, comp1))
        is_(comp1.column, t.c.y)
        is_(t.c.y.server_onupdate, comp1)
        is_(t.c.y.server_default, comp1)

        m2 = MetaData()
        t2 = t.to_metadata(m2)
        comp2 = t2.c.y.server_default

        is_not(comp1, comp2)

        is_(comp1.column, t.c.y)
        is_(t.c.y.server_onupdate, comp1)
        is_(t.c.y.server_default, comp1)

        is_(comp2.column, t2.c.y)
        is_(t2.c.y.server_onupdate, comp2)
        is_(t2.c.y.server_default, comp2)