Ticket #19625: django19625-master.fix_using_django_conversions.patch

django/db/backends/mysql/base.py

@@ -6 +6 @@
 from __future__ import unicode_literals
 
 import datetime
+import decimal
 import re
 import sys
 import warnings
@@ -73 +74 @@
         value = value.astimezone(timezone.utc).replace(tzinfo=None)
     return Thing2Literal(value.strftime("%Y-%m-%d %H:%M:%S"), conv)
 
+def rev_typecast_decimal(value, conv):
+    # value is always an instance of decimal.Decimal
+    if value.is_normal() or value.is_zero():
+        return str(value)
+    raise ValueError('Cannot express %r in a way mysql understands' % value)
+
 # MySQLdb-1.2.1 returns TIME columns as timedelta -- they are more like
 # timedelta in terms of actual behavior as they are signed and include days --
 # and Django expects time, so we still need to override that. We also need to
@@ -87 +94 @@
     FIELD_TYPE.NEWDECIMAL: util.typecast_decimal,
     FIELD_TYPE.DATETIME: parse_datetime_with_timezone_support,
     datetime.datetime: adapt_datetime_with_timezone_support,
+    decimal.Decimal: rev_typecast_decimal,
 })
 
 # This should match the numerical portion of the version numbers (we can treat

new file tests/modeltests/long_decimal/models.py

@@ +1 @@
+# -*- coding: utf-8 -*-
+"""
+12. Using a decimal field in lookups
+
+MySQL does not convert strings to Decimals that well. Make sure inserting
+and filtering works properly.
+"""
+
+from __future__ import absolute_import
+
+from django.db import models
+
+try:
+    from django.utils.encoding import python_2_unicode_compatible
+except ImportError:
+    python_2_unicode_compatible = None
+
+
+class Book(models.Model):
+    isbn = models.DecimalField(max_digits=31, decimal_places=0, db_index=True)
+    name = models.CharField(max_length=63)
+
+    def __str__(self):
+        return "%s %s" % (self.isbn, self.name)
+
+
+if python_2_unicode_compatible:
+    Book = python_2_unicode_compatible(Book)

new file tests/modeltests/long_decimal/tests.py

@@ +1 @@
+# vim: set ts=8 sw=4 sts=4 et ai:
+from __future__ import absolute_import, unicode_literals
+
+from decimal import Decimal
+
+from django.test import TestCase
+
+from .models import Book
+
+"""
+Note that this problem is fixed in MySQL somewhere between
+version 5.1.66 and 5.5.28.
+
+Test with:
+
+create table abc (value decimal(31,0));
+insert into abc values (1234567890123456789012345678901);
+select * from abc where value = 1234567890123456789012345678901;
+select * from abc where value = '1234567890123456789012345678901';
+drop table abc;
+
+In the broken case, you won't get a result for the second query.
+
+The fix is to have Django always send decimals to the SQL backend as-is
+and not as a quoted string.
+"""
+
+class DecimalTests(TestCase):
+    def help_decimal_field(self, elements, iterable):
+        try:
+            self.help_decimal_field_setup(elements, iterable)
+            self.help_decimal_field_test(elements, iterable)
+        finally:
+            Book.objects.all().delete()
+
+    def help_decimal_field_values(self, elements, size):
+        value = ''.join([elements[(i % len(elements))] for i in range(size)])
+        isbn = Decimal(value)
+        name = 'ISBN:%s' % (value,)
+        return isbn, name
+
+    def help_decimal_field_setup(self, elements, iterable):
+        for size in iterable:
+            isbn, name = self.help_decimal_field_values(elements, size)
+            Book.objects.create(isbn=isbn, name=name)
+
+    def help_decimal_field_test(self, elements, iterable):
+        for size in iterable:
+            isbn, name = self.help_decimal_field_values(elements, size)
+            try:
+                book = Book.objects.get(isbn=isbn)
+            except Book.DoesNotExist:
+                self.assertFalse(True, 'book with isbn %s was not found' % (
+                                 isbn,))
+            except:
+                # Certain fixes can produce an unexpected MySQL Warning..
+                import sys
+                print >>sys.stderr, '( failure when getting', isbn, ')'
+                raise
+            else:
+                self.assertEqual(book.isbn, isbn)
+                self.assertEqual(book.name, name)
+
+    def test_baseline(self):
+        """
+        This should always work. The point was that larger decimals get
+        cast to a lossy float. For small values, there is no loss.
+        """
+        try:
+            Book.objects.create(isbn=Decimal('987'), name='baseline')
+            baseline = Book.objects.get(isbn=Decimal('987'))
+            self.assertEquals(baseline.name, 'baseline')
+        finally:
+            Book.objects.all().delete()
+
+    def test_non_normal(self):
+        # get_db_prep_save throws exceptions on nonnormal decimals
+        # but select queries only pass them to the conversion mapping
+        self.assertRaises(ValueError, Book.objects.get, isbn=Decimal('Infinity'))
+        self.assertRaises(ValueError, Book.objects.get, isbn=Decimal('-Infinity'))
+        self.assertRaises(ValueError, Book.objects.get, isbn=Decimal('NaN'))
+        # zero is a non normal decimal
+        try:
+            Book.objects.create(isbn=Decimal('0'), name='zero')
+            book = Book.objects.get(isbn=Decimal('0'))
+            self.assertEquals(book.name, 'zero')
+            book = Book.objects.get(isbn=Decimal('-0'))
+            self.assertEquals(book.name, 'zero')
+
+            Book.objects.create(isbn=Decimal('1.0E+3'), name='1k')
+            book = Book.objects.get(isbn=Decimal('1.0E+3'))
+            self.assertEquals(book.name, '1k')
+            book = Book.objects.get(isbn=Decimal('1000'))
+            self.assertEquals(book.name, '1k')
+        finally:
+            Book.objects.all().delete()
+
+    def test_decimal_field_works1(self):
+        """
+        For some reason, the test doesn't fail when we iterate with this
+        test from 1 to 31.
+        """
+        self.help_decimal_field('1234567890', range(1, 32))
+
+    def test_decimal_field_works2(self):
+        """
+        The original test reversed. Works too.
+        """
+        self.help_decimal_field('1234567890', range(31, 0, -1))
+
+    def test_decimal_field_broken1(self):
+        """
+        Testing with just one element. This fails nicely.
+
+        This fails on:
+        * MySQL 5.1.66
+
+        Doesn't fail on:
+        * MySQL 5.5.28
+        """
+        self.help_decimal_field('1234567890', [31])
+
+    def test_decimal_field_broken2(self):
+        """
+        Testing with just one element. This fails nicely.
+
+        This fails on:
+        * MySQL 5.1.66
+
+        Doesn't fail on:
+        * MySQL 5.5.28
+        """
+        self.help_decimal_field('1234567890', [22])
+
+    def test_decimal_field_broken3(self):
+        """
+        Testing with just one element. This fails nicely.
+
+        This fails on:
+        * MySQL 5.1.66
+
+        Doesn't fail on:
+        * MySQL 5.5.28
+        """
+        self.help_decimal_field('1234567890', [18])