On 04/05/12 20:00, Jan Urbański wrote:
On 03/05/12 11:04, Jan Urbański wrote:
On 02/05/12 20:18, Peter Eisentraut wrote:
This doesn't work anymore with Python 3:
rv = plpy.execute(...)
do_something(rv[0:1])
Sounds ugly. I'll take a look.
I found some instructions on how to deal with the Python 2/Python 3
slicing mess:
http://renesd.blogspot.com/2009/07/python3-c-api-simple-slicing-sqslice.html
Thanks to the helpful folk at #python I found out that the fix is much
easier. Attached is a patch that fixes the bug and passes regression
tests on Pythons 2.3 through 3.2.
Apparently once you implement PyMappingMethods.mp_subscript you can drop
PySequenceMethods.sq_slice, but I guess there's no harm in keeping it
(and I'm not sure it'd work on Python 2.3 with only mp_subscript
implemented).
Do we want to backpatch this? If so, I'd need to produce a version that
applies to the monolithic plpython.c file from the previous releases.
Cheers,
Jan
>From 000a1285d66c65c36ae6fa064266f00def5ee9d7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Urba=C5=84ski?= <wulc...@wulczer.org>
Date: Sat, 5 May 2012 22:39:26 +0200
Subject: [PATCH] Fix slicing support for result objects for Python 3.
The old way of implementing slicing support by implementing
PySequenceMethods.sq_slice has been deprecated in Python 3, you should
not implement PyMappingMethods.mp_subscript. Do this by simply
proxying the call to the wrapped list of result dictionaries.
While at it, fix an incorrect comment about PLyResultObject->rows being
None if the result set is empty (it actually is an empty list in that
case).
---
src/pl/plpython/expected/plpython_spi.out | 55 +++++++++++++++++++++++++++++
src/pl/plpython/plpy_resultobject.c | 27 +++++++++++++-
src/pl/plpython/plpy_resultobject.h | 2 +-
src/pl/plpython/sql/plpython_spi.sql | 36 +++++++++++++++++++
4 files changed, 118 insertions(+), 2 deletions(-)
diff --git a/src/pl/plpython/expected/plpython_spi.out b/src/pl/plpython/expected/plpython_spi.out
index 671c24e..54ef512 100644
--- a/src/pl/plpython/expected/plpython_spi.out
+++ b/src/pl/plpython/expected/plpython_spi.out
@@ -228,6 +228,61 @@ SELECT result_len_test($$UPDATE foo3 SET b= '' WHERE a = 2$$);
0
(1 row)
+CREATE FUNCTION result_subscript_test() RETURNS void
+AS $$
+result = plpy.execute("SELECT 1 AS c UNION SELECT 2 "
+ "UNION SELECT 3 UNION SELECT 4")
+
+plpy.info(result[1]['c'])
+plpy.info(result[-1]['c'])
+
+plpy.info([item['c'] for item in result[1:3]])
+plpy.info([item['c'] for item in result[::2]])
+
+result[-1] = {'c': 1000}
+result[:2] = [{'c': 10}, {'c': 100}]
+plpy.info([item['c'] for item in result[:]])
+
+# raises TypeError, but the message differs on Python 2.6, so silence it
+try:
+ plpy.info(result['foo'])
+except TypeError:
+ pass
+else:
+ assert False, "TypeError not raised"
+
+$$ LANGUAGE plpythonu;
+SELECT result_subscript_test();
+INFO: 2
+CONTEXT: PL/Python function "result_subscript_test"
+INFO: 4
+CONTEXT: PL/Python function "result_subscript_test"
+INFO: [2, 3]
+CONTEXT: PL/Python function "result_subscript_test"
+INFO: [1, 3]
+CONTEXT: PL/Python function "result_subscript_test"
+INFO: [10, 100, 3, 1000]
+CONTEXT: PL/Python function "result_subscript_test"
+ result_subscript_test
+-----------------------
+
+(1 row)
+
+CREATE FUNCTION result_empty_test() RETURNS void
+AS $$
+result = plpy.execute("select 1 where false")
+
+plpy.info(result[:])
+
+$$ LANGUAGE plpythonu;
+SELECT result_empty_test();
+INFO: []
+CONTEXT: PL/Python function "result_empty_test"
+ result_empty_test
+-------------------
+
+(1 row)
+
-- cursor objects
CREATE FUNCTION simple_cursor_test() RETURNS int AS $$
res = plpy.cursor("select fname, lname from users")
diff --git a/src/pl/plpython/plpy_resultobject.c b/src/pl/plpython/plpy_resultobject.c
index fcf8074..06ba2ee 100644
--- a/src/pl/plpython/plpy_resultobject.c
+++ b/src/pl/plpython/plpy_resultobject.c
@@ -23,6 +23,9 @@ static PyObject *PLy_result_item(PyObject *arg, Py_ssize_t idx);
static PyObject *PLy_result_slice(PyObject *arg, Py_ssize_t lidx, Py_ssize_t hidx);
static int PLy_result_ass_item(PyObject *arg, Py_ssize_t idx, PyObject *item);
static int PLy_result_ass_slice(PyObject *rg, Py_ssize_t lidx, Py_ssize_t hidx, PyObject *slice);
+static PyObject *PLy_result_subscript(PyObject *arg, PyObject *item);
+static PyObject *PLy_result_subscript(PyObject *arg, PyObject *item);
+static int PLy_result_ass_subscript(PyObject* self, PyObject* item, PyObject* value);
static char PLy_result_doc[] = {
"Results of a PostgreSQL query"
@@ -38,6 +41,12 @@ static PySequenceMethods PLy_result_as_sequence = {
PLy_result_ass_slice, /* sq_ass_slice */
};
+static PyMappingMethods PLy_result_as_mapping = {
+ PLy_result_length, /* mp_length */
+ PLy_result_subscript, /* mp_subscript */
+ PLy_result_ass_subscript, /* mp_ass_subscript */
+};
+
static PyMethodDef PLy_result_methods[] = {
{"colnames", PLy_result_colnames, METH_NOARGS, NULL},
{"coltypes", PLy_result_coltypes, METH_NOARGS, NULL},
@@ -64,7 +73,7 @@ static PyTypeObject PLy_ResultType = {
0, /* tp_repr */
0, /* tp_as_number */
&PLy_result_as_sequence, /* tp_as_sequence */
- 0, /* tp_as_mapping */
+ &PLy_result_as_mapping, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
@@ -251,3 +260,19 @@ PLy_result_ass_slice(PyObject *arg, Py_ssize_t lidx, Py_ssize_t hidx, PyObject *
rv = PyList_SetSlice(ob->rows, lidx, hidx, slice);
return rv;
}
+
+static PyObject *
+PLy_result_subscript(PyObject *arg, PyObject *item)
+{
+ PLyResultObject *ob = (PLyResultObject *) arg;
+
+ return PyObject_GetItem(ob->rows, item);
+}
+
+static int
+PLy_result_ass_subscript(PyObject *arg, PyObject *item, PyObject *value)
+{
+ PLyResultObject *ob = (PLyResultObject *) arg;
+
+ return PyObject_SetItem(ob->rows, item, value);
+}
diff --git a/src/pl/plpython/plpy_resultobject.h b/src/pl/plpython/plpy_resultobject.h
index 1b37d1d..c5ba999 100644
--- a/src/pl/plpython/plpy_resultobject.h
+++ b/src/pl/plpython/plpy_resultobject.h
@@ -13,7 +13,7 @@ typedef struct PLyResultObject
PyObject_HEAD
/* HeapTuple *tuples; */
PyObject *nrows; /* number of rows returned by query */
- PyObject *rows; /* data rows, or None if no data returned */
+ PyObject *rows; /* data rows, or empty list if no data returned */
PyObject *status; /* query status, SPI_OK_*, or SPI_ERR_* */
TupleDesc tupdesc;
} PLyResultObject;
diff --git a/src/pl/plpython/sql/plpython_spi.sql b/src/pl/plpython/sql/plpython_spi.sql
index 7be2fbf..cf0128c 100644
--- a/src/pl/plpython/sql/plpython_spi.sql
+++ b/src/pl/plpython/sql/plpython_spi.sql
@@ -147,6 +147,42 @@ SELECT result_len_test($$CREATE TEMPORARY TABLE foo3 (a int, b text)$$);
SELECT result_len_test($$INSERT INTO foo3 VALUES (1, 'one'), (2, 'two')$$);
SELECT result_len_test($$UPDATE foo3 SET b= '' WHERE a = 2$$);
+CREATE FUNCTION result_subscript_test() RETURNS void
+AS $$
+result = plpy.execute("SELECT 1 AS c UNION SELECT 2 "
+ "UNION SELECT 3 UNION SELECT 4")
+
+plpy.info(result[1]['c'])
+plpy.info(result[-1]['c'])
+
+plpy.info([item['c'] for item in result[1:3]])
+plpy.info([item['c'] for item in result[::2]])
+
+result[-1] = {'c': 1000}
+result[:2] = [{'c': 10}, {'c': 100}]
+plpy.info([item['c'] for item in result[:]])
+
+# raises TypeError, but the message differs on Python 2.6, so silence it
+try:
+ plpy.info(result['foo'])
+except TypeError:
+ pass
+else:
+ assert False, "TypeError not raised"
+
+$$ LANGUAGE plpythonu;
+
+SELECT result_subscript_test();
+
+CREATE FUNCTION result_empty_test() RETURNS void
+AS $$
+result = plpy.execute("select 1 where false")
+
+plpy.info(result[:])
+
+$$ LANGUAGE plpythonu;
+
+SELECT result_empty_test();
-- cursor objects
--
1.7.10
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