Added basic sql module implementation

lib/sql.py

@@ -23,3 +23,177 @@
 # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 # License for more details.
 
+from psycopg2 import extensions as ext
+
+
+class Composible(object):
+    """Base class for objects that can be used to compose an SQL string."""
+    def as_string(self, conn_or_curs):
+        raise NotImplementedError
+
+    def __add__(self, other):
+        if isinstance(other, Composed):
+            return Composed([self]) + other
+        if isinstance(other, Composible):
+            return Composed([self]) + Composed([other])
+        else:
+            return NotImplemented
+
+
+class Composed(Composible):
+    def __init__(self, seq):
+        self._seq = []
+        for i in seq:
+            if not isinstance(i, Composible):
+                raise TypeError(
+                    "Composed elements must be Composible, got %r instead" % i)
+            self._seq.append(i)
+
+    def __repr__(self):
+        return "sql.Composed(%r)" % (self.seq,)
+
+    def as_string(self, conn_or_curs):
+        rv = []
+        for i in self._seq:
+            rv.append(i.as_string(conn_or_curs))
+        return ''.join(rv)
+
+    def __add__(self, other):
+        if isinstance(other, Composed):
+            return Composed(self._seq + other._seq)
+        if isinstance(other, Composible):
+            return Composed(self._seq + [other])
+        else:
+            return NotImplemented
+
+    def __mul__(self, n):
+        return Composed(self._seq * n)
+
+    def join(self, joiner):
+        if isinstance(joiner, basestring):
+            joiner = SQL(joiner)
+        elif not isinstance(joiner, SQL):
+            raise TypeError(
+                "Composed.join() argument must be a string or an SQL")
+
+        if len(self._seq) <= 1:
+            return self
+
+        it = iter(self._seq)
+        rv = [it.next()]
+        for i in it:
+            rv.append(joiner)
+            rv.append(i)
+
+        return Composed(rv)
+
+
+class SQL(Composible):
+    def __init__(self, wrapped):
+        if not isinstance(wrapped, basestring):
+            raise TypeError("SQL values must be strings")
+        self._wrapped = wrapped
+
+    def __repr__(self):
+        return "sql.SQL(%r)" % (self._wrapped,)
+
+    def as_string(self, conn_or_curs):
+        return self._wrapped
+
+    def __mul__(self, n):
+        return Composed([self] * n)
+
+    def join(self, seq):
+        rv = []
+        it = iter(seq)
+        try:
+            rv.append(it.next())
+        except StopIteration:
+            pass
+        else:
+            for i in it:
+                rv.append(self)
+                rv.append(i)
+
+        return Composed(rv)
+
+
+class Identifier(Composible):
+    def __init__(self, wrapped):
+        if not isinstance(wrapped, basestring):
+            raise TypeError("SQL identifiers must be strings")
+
+        self._wrapped = wrapped
+
+    @property
+    def wrapped(self):
+        return self._wrapped
+
+    def __repr__(self):
+        return "sql.Identifier(%r)" % (self._wrapped,)
+
+    def as_string(self, conn_or_curs):
+        return ext.quote_ident(self._wrapped, conn_or_curs)
+
+
+class Literal(Composible):
+    def __init__(self, wrapped):
+        self._wrapped = wrapped
+
+    def __repr__(self):
+        return "sql.Literal(%r)" % (self._wrapped,)
+
+    def as_string(self, conn_or_curs):
+        a = ext.adapt(self._wrapped)
+        if hasattr(a, 'prepare'):
+            # is it a connection or cursor?
+            if isinstance(conn_or_curs, ext.connection):
+                conn = conn_or_curs
+            elif isinstance(conn_or_curs, ext.cursor):
+                conn = conn_or_curs.connection
+            else:
+                raise TypeError("conn_or_curs must be a connection or a cursor")
+
+            a.prepare(conn)
+
+        return a.getquoted()
+
+    def __mul__(self, n):
+        return Composed([self] * n)
+
+
+class Placeholder(Composible):
+    def __init__(self, name=None):
+        if isinstance(name, basestring):
+            if ')' in name:
+                raise ValueError("invalid name: %r" % name)
+
+        elif name is not None:
+            raise TypeError("expected string or None as name, got %r" % name)
+
+        self._name = name
+
+    def __repr__(self):
+        return "sql.Placeholder(%r)" % (
+            self._name if self._name is not None else '',)
+
+    def __mul__(self, n):
+        return Composed([self] * n)
+
+    def as_string(self, conn_or_curs):
+        if self._name is not None:
+            return "%%(%s)s" % self._name
+        else:
+            return "%s"
+
+
+def compose(sql, args=()):
+    raise NotImplementedError
+
+
+# Alias
+PH = Placeholder
+
+# Literals
+NULL = SQL("NULL")
+DEFAULT = SQL("DEFAULT")

tests/test_sql.py

@@ -22,7 +22,228 @@
 # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 # License for more details.
 
-from testutils import unittest
+import datetime as dt
+from testutils import unittest, ConnectingTestCase
+
+from psycopg2 import sql
+
+
+class ComposeTests(ConnectingTestCase):
+    def test_pos(self):
+        s = sql.compose("select %s from %s",
+            (sql.Identifier('field'), sql.Identifier('table')))
+        s1 = s.as_string(self.conn)
+        self.assert_(isinstance(s1, str))
+        self.assertEqual(s1, 'select "field" from "table"')
+
+    def test_dict(self):
+        s = sql.compose("select %(f)s from %(t)s",
+            {'f': sql.Identifier('field'), 't': sql.Identifier('table')})
+        s1 = s.as_string(self.conn)
+        self.assert_(isinstance(s1, str))
+        self.assertEqual(s1, 'select "field" from "table"')
+
+    def test_unicode(self):
+        s = sql.compose(u"select %s from %s",
+            (sql.Identifier(u'field'), sql.Identifier('table')))
+        s1 = s.as_string(self.conn)
+        self.assert_(isinstance(s1, unicode))
+        self.assertEqual(s1, u'select "field" from "table"')
+
+    def test_compose_literal(self):
+        s = sql.compose("select %s;", [sql.Literal(dt.date(2016, 12, 31))])
+        s1 = s.as_string(self.conn)
+        self.assertEqual(s1, "select '2016-12-31'::date;")
+
+    def test_must_be_adaptable(self):
+        class Foo(object):
+            pass
+
+        self.assertRaises(TypeError,
+            sql.compose, "select %s;", [Foo()])
+
+    def test_execute(self):
+        cur = self.conn.cursor()
+        cur.execute("""
+            create table test_compose (
+                id serial primary key,
+                foo text, bar text, "ba'z" text)
+            """)
+        cur.execute(
+            sql.compose("insert into %s (id, %s) values (%%s, %s)", [
+                sql.Identifier('test_compose'),
+                sql.SQL(', ').join(map(sql.Identifier, ['foo', 'bar', "ba'z"])),
+                (sql.PH() * 3).join(', '),
+            ]),
+            (10, 'a', 'b', 'c'))
+
+        cur.execute("select * from test_compose")
+        self.assertEqual(cur.fetchall(), [(10, 'a', 'b', 'c')])
+
+    def test_executemany(self):
+        cur = self.conn.cursor()
+        cur.execute("""
+            create table test_compose (
+                id serial primary key,
+                foo text, bar text, "ba'z" text)
+            """)
+        cur.executemany(
+            sql.compose("insert into %s (id, %s) values (%%s, %s)", [
+                sql.Identifier('test_compose'),
+                sql.SQL(', ').join(map(sql.Identifier, ['foo', 'bar', "ba'z"])),
+                (sql.PH() * 3).join(', '),
+            ]),
+            [(10, 'a', 'b', 'c'), (20, 'd', 'e', 'f')])
+
+        cur.execute("select * from test_compose")
+        self.assertEqual(cur.fetchall(),
+            [(10, 'a', 'b', 'c'), (20, 'd', 'e', 'f')])
+
+
+class IdentifierTests(ConnectingTestCase):
+    def test_class(self):
+        self.assert_(issubclass(sql.Identifier, sql.Composible))
+
+    def test_init(self):
+        self.assert_(isinstance(sql.Identifier('foo'), sql.Identifier))
+        self.assert_(isinstance(sql.Identifier(u'foo'), sql.Identifier))
+        self.assert_(isinstance(sql.Identifier(b'foo'), sql.Identifier))
+        self.assertRaises(TypeError, sql.Identifier, 10)
+        self.assertRaises(TypeError, sql.Identifier, dt.date(2016, 12, 31))
+
+    def test_repr(self):
+        obj = sql.Identifier("fo'o")
+        self.assertEqual(repr(obj), 'sql.Identifier("fo\'o")')
+        self.assertEqual(repr(obj), str(obj))
+
+    def test_as_str(self):
+        self.assertEqual(sql.Identifier('foo').as_string(self.conn), '"foo"')
+        self.assertEqual(sql.Identifier("fo'o").as_string(self.conn), '"fo\'o"')
+
+    def test_join(self):
+        self.assert_(not hasattr(sql.Identifier('foo'), 'join'))
+
+
+class LiteralTests(ConnectingTestCase):
+    def test_class(self):
+        self.assert_(issubclass(sql.Literal, sql.Composible))
+
+    def test_init(self):
+        self.assert_(isinstance(sql.Literal('foo'), sql.Literal))
+        self.assert_(isinstance(sql.Literal(u'foo'), sql.Literal))
+        self.assert_(isinstance(sql.Literal(b'foo'), sql.Literal))
+        self.assert_(isinstance(sql.Literal(42), sql.Literal))
+        self.assert_(isinstance(
+            sql.Literal(dt.date(2016, 12, 31)), sql.Literal))
+
+    def test_repr(self):
+        self.assertEqual(repr(sql.Literal("foo")), "sql.Literal('foo')")
+        self.assertEqual(str(sql.Literal("foo")), "sql.Literal('foo')")
+        self.assertEqual(
+            sql.Literal("foo").as_string(self.conn).replace("E'", "'"),
+            "'foo'")
+        self.assertEqual(sql.Literal(42).as_string(self.conn), "42")
+        self.assertEqual(
+            sql.Literal(dt.date(2017, 1, 1)).as_string(self.conn),
+            "'2017-01-01'::date")
+
+
+class SQLTests(ConnectingTestCase):
+    def test_class(self):
+        self.assert_(issubclass(sql.SQL, sql.Composible))
+
+    def test_init(self):
+        self.assert_(isinstance(sql.SQL('foo'), sql.SQL))
+        self.assert_(isinstance(sql.SQL(u'foo'), sql.SQL))
+        self.assert_(isinstance(sql.SQL(b'foo'), sql.SQL))
+        self.assertRaises(TypeError, sql.SQL, 10)
+        self.assertRaises(TypeError, sql.SQL, dt.date(2016, 12, 31))
+
+    def test_str(self):
+        self.assertEqual(repr(sql.SQL("foo")), "sql.SQL('foo')")
+        self.assertEqual(str(sql.SQL("foo")), "sql.SQL('foo')")
+        self.assertEqual(sql.SQL("foo").as_string(self.conn), "foo")
+
+    def test_sum(self):
+        obj = sql.SQL("foo") + sql.SQL("bar")
+        self.assert_(isinstance(obj, sql.Composed))
+        self.assertEqual(obj.as_string(self.conn), "foobar")
+
+    def test_sum_inplace(self):
+        obj = sql.SQL("foo")
+        obj += sql.SQL("bar")
+        self.assert_(isinstance(obj, sql.Composed))
+        self.assertEqual(obj.as_string(self.conn), "foobar")
+
+    def test_multiply(self):
+        obj = sql.SQL("foo") * 3
+        self.assert_(isinstance(obj, sql.Composed))
+        self.assertEqual(obj.as_string(self.conn), "foofoofoo")
+
+    def test_join(self):
+        obj = sql.SQL(", ").join(
+            [sql.Identifier('foo'), sql.SQL('bar'), sql.Literal(42)])
+        self.assert_(isinstance(obj, sql.Composed))
+        self.assertEqual(obj.as_string(self.conn), '"foo", bar, 42')
+
+
+class ComposedTest(ConnectingTestCase):
+    def test_class(self):
+        self.assert_(issubclass(sql.Composed, sql.Composible))
+
+    def test_join(self):
+        obj = sql.Composed([sql.Literal("foo"), sql.Identifier("b'ar")])
+        obj = obj.join(", ")
+        self.assert_(isinstance(obj, sql.Composed))
+        self.assertEqual(obj.as_string(self.conn), "'foo', \"b'ar\"")
+
+    def test_sum(self):
+        obj = sql.Composed([sql.SQL("foo ")])
+        obj = obj + sql.Literal("bar")
+        self.assert_(isinstance(obj, sql.Composed))
+        self.assertEqual(obj.as_string(self.conn), "foo 'bar'")
+
+    def test_sum_inplace(self):
+        obj = sql.Composed([sql.SQL("foo ")])
+        obj += sql.Literal("bar")
+        self.assert_(isinstance(obj, sql.Composed))
+        self.assertEqual(obj.as_string(self.conn), "foo 'bar'")
+
+        obj = sql.Composed([sql.SQL("foo ")])
+        obj += sql.Composed([sql.Literal("bar")])
+        self.assert_(isinstance(obj, sql.Composed))
+        self.assertEqual(obj.as_string(self.conn), "foo 'bar'")
+
+
+class PlaceholderTest(ConnectingTestCase):
+    def test_class(self):
+        self.assert_(issubclass(sql.Placeholder, sql.Composible))
+
+    def test_alias(self):
+        self.assert_(sql.Placeholder is sql.PH)
+
+    def test_repr(self):
+        self.assert_(str(sql.Placeholder()), 'sql.Placeholder()')
+        self.assert_(repr(sql.Placeholder()), 'sql.Placeholder()')
+        self.assert_(sql.Placeholder().as_string(self.conn), '%s')
+
+    def test_repr_name(self):
+        self.assert_(str(sql.Placeholder('foo')), "sql.Placeholder('foo')")
+        self.assert_(repr(sql.Placeholder('foo')), "sql.Placeholder('foo')")
+        self.assert_(sql.Placeholder('foo').as_string(self.conn), '%(foo)s')
+
+    def test_bad_name(self):
+        self.assertRaises(ValueError, sql.Placeholder, ')')
+
+
+class ValuesTest(ConnectingTestCase):
+    def test_null(self):
+        self.assert_(isinstance(sql.NULL, sql.SQL))
+        self.assertEqual(sql.NULL.as_string(self.conn), "NULL")
+
+    def test_default(self):
+        self.assert_(isinstance(sql.DEFAULT, sql.SQL))
+        self.assertEqual(sql.DEFAULT.as_string(self.conn), "DEFAULT")
 
 
 def test_suite():