sqlalchemy/test/sql/test_case_statement.py

from sqlalchemy import and_
from sqlalchemy import case
from sqlalchemy import cast
from sqlalchemy import Column
from sqlalchemy import exc
from sqlalchemy import Integer
from sqlalchemy import literal_column
from sqlalchemy import MetaData
from sqlalchemy import select
from sqlalchemy import String
from sqlalchemy import Table
from sqlalchemy import testing
from sqlalchemy import text
from sqlalchemy.sql import column
from sqlalchemy.sql import table
from sqlalchemy.testing import assert_raises_message
from sqlalchemy.testing import AssertsCompiledSQL
from sqlalchemy.testing import eq_
from sqlalchemy.testing import fixtures


info_table = None


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

    @classmethod
    def setup_test_class(cls):
        metadata = MetaData()
        global info_table
        info_table = Table(
            "infos",
            metadata,
            Column("pk", Integer, primary_key=True),
            Column("info", String(30)),
        )

        with testing.db.begin() as conn:
            info_table.create(conn)

            conn.execute(
                info_table.insert(),
                [
                    {"pk": 1, "info": "pk_1_data"},
                    {"pk": 2, "info": "pk_2_data"},
                    {"pk": 3, "info": "pk_3_data"},
                    {"pk": 4, "info": "pk_4_data"},
                    {"pk": 5, "info": "pk_5_data"},
                    {"pk": 6, "info": "pk_6_data"},
                ],
            )

    @classmethod
    def teardown_test_class(cls):
        with testing.db.begin() as conn:
            info_table.drop(conn)

    @testing.fails_on("firebird", "FIXME: unknown")
    @testing.requires.subqueries
    def test_case(self, connection):
        inner = select(
            case(
                (info_table.c.pk < 3, "lessthan3"),
                (and_(info_table.c.pk >= 3, info_table.c.pk < 7), "gt3"),
            ).label("x"),
            info_table.c.pk,
            info_table.c.info,
        ).select_from(info_table)

        inner_result = connection.execute(inner).all()

        # Outputs:
        # lessthan3 1 pk_1_data
        # lessthan3 2 pk_2_data
        # gt3 3 pk_3_data
        # gt3 4 pk_4_data
        # gt3 5 pk_5_data
        # gt3 6 pk_6_data
        eq_(
            inner_result,
            [
                ("lessthan3", 1, "pk_1_data"),
                ("lessthan3", 2, "pk_2_data"),
                ("gt3", 3, "pk_3_data"),
                ("gt3", 4, "pk_4_data"),
                ("gt3", 5, "pk_5_data"),
                ("gt3", 6, "pk_6_data"),
            ],
        )

        outer = select(inner.alias("q_inner"))

        outer_result = connection.execute(outer).all()

        assert outer_result == [
            ("lessthan3", 1, "pk_1_data"),
            ("lessthan3", 2, "pk_2_data"),
            ("gt3", 3, "pk_3_data"),
            ("gt3", 4, "pk_4_data"),
            ("gt3", 5, "pk_5_data"),
            ("gt3", 6, "pk_6_data"),
        ]

        w_else = select(
            case(
                [info_table.c.pk < 3, cast(3, Integer)],
                [and_(info_table.c.pk >= 3, info_table.c.pk < 6), 6],
                else_=0,
            ).label("x"),
            info_table.c.pk,
            info_table.c.info,
        ).select_from(info_table)

        else_result = connection.execute(w_else).all()

        eq_(
            else_result,
            [
                (3, 1, "pk_1_data"),
                (3, 2, "pk_2_data"),
                (6, 3, "pk_3_data"),
                (6, 4, "pk_4_data"),
                (6, 5, "pk_5_data"),
                (0, 6, "pk_6_data"),
            ],
        )

    def test_literal_interpretation_ambiguous(self):
        assert_raises_message(
            exc.ArgumentError,
            r"Column expression expected, got 'x'",
            case,
            ("x", "y"),
        )

    def test_literal_interpretation_ambiguous_tuple(self):
        assert_raises_message(
            exc.ArgumentError,
            r"Column expression expected, got \('x', 'y'\)",
            case,
            (("x", "y"), "z"),
        )

    def test_literal_interpretation(self):
        t = table("test", column("col1"))

        self.assert_compile(
            case(("x", "y"), value=t.c.col1),
            "CASE test.col1 WHEN :param_1 THEN :param_2 END",
        )
        self.assert_compile(
            case((t.c.col1 == 7, "y"), else_="z"),
            "CASE WHEN (test.col1 = :col1_1) THEN :param_1 ELSE :param_2 END",
        )

    @testing.combinations(
        (
            (lambda t: ({"x": "y"}, t.c.col1, None)),
            "CASE test.col1 WHEN :param_1 THEN :param_2 END",
        ),
        (
            (lambda t: ({"x": "y", "p": "q"}, t.c.col1, None)),
            "CASE test.col1 WHEN :param_1 THEN :param_2 "
            "WHEN :param_3 THEN :param_4 END",
        ),
        (
            (lambda t: ({t.c.col1 == 7: "x"}, None, 10)),
            "CASE WHEN (test.col1 = :col1_1) THEN :param_1 ELSE :param_2 END",
        ),
        (
            (lambda t: ({t.c.col1 == 7: "x", t.c.col1 == 10: "y"}, None, 10)),
            "CASE WHEN (test.col1 = :col1_1) THEN :param_1 "
            "WHEN (test.col1 = :col1_2) THEN :param_2 ELSE :param_3 END",
        ),
        argnames="test_case, expected",
    )
    @testing.combinations(("positional",), ("kwarg",), argnames="argstyle")
    def test_when_dicts(self, argstyle, test_case, expected):
        t = table("test", column("col1"))

        whens, value, else_ = testing.resolve_lambda(test_case, t=t)

        def _case_args(whens, value=None, else_=None):
            kw = {}
            if value is not None:
                kw["value"] = value
            if else_ is not None:
                kw["else_"] = else_

            if argstyle == "kwarg":
                return case(whens=whens, **kw)
            elif argstyle == "positional":
                return case(whens, **kw)

            # note: 1.3 also does not allow this form
            # case([whens], **kw)

        self.assert_compile(
            _case_args(whens=whens, value=value, else_=else_),
            expected,
        )

    def test_text_doesnt_explode(self, connection):

        for s in [
            select(
                case(
                    (info_table.c.info == "pk_4_data", text("'yes'")),
                    else_=text("'no'"),
                )
            ).order_by(info_table.c.info),
            select(
                case(
                    (
                        info_table.c.info == "pk_4_data",
                        literal_column("'yes'"),
                    ),
                    else_=literal_column("'no'"),
                )
            ).order_by(info_table.c.info),
        ]:
            eq_(
                connection.execute(s).all(),
                [("no",), ("no",), ("no",), ("yes",), ("no",), ("no",)],
            )

    def testcase_with_dict(self):
        query = select(
            case(
                {
                    info_table.c.pk < 3: "lessthan3",
                    info_table.c.pk >= 3: "gt3",
                },
                else_="other",
            ),
            info_table.c.pk,
            info_table.c.info,
        ).select_from(info_table)
        eq_(
            query.execute().fetchall(),
            [
                ("lessthan3", 1, "pk_1_data"),
                ("lessthan3", 2, "pk_2_data"),
                ("gt3", 3, "pk_3_data"),
                ("gt3", 4, "pk_4_data"),
                ("gt3", 5, "pk_5_data"),
                ("gt3", 6, "pk_6_data"),
            ],
        )

        simple_query = (
            select(
                case(
                    {1: "one", 2: "two"}, value=info_table.c.pk, else_="other"
                ),
                info_table.c.pk,
            )
            .where(info_table.c.pk < 4)
            .select_from(info_table)
        )

        assert simple_query.execute().fetchall() == [
            ("one", 1),
            ("two", 2),
            ("other", 3),
        ]