id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
4193	Error in creation of foreign key depends on spelling of field class	gerry@…	Philippe Raoult	"= Summary =

When a field class named ""Vehicle"" is attempted to be used as a foreign key, the SQL generated by django is incorrect.
Changing the name of the class to ""Vahicle"" or some other misspelling that does not begin with ""Veh"" results in the correct behavior.

= Example =

The following model definition does not work as expected. (N.B. I've trimmed some code to reduce the model definition to its essential bug-revealing form.)
{{{
from django.db import models
import datetime

class Vehicle(models.Model):
    type = models.CharField(maxlength=15)           #  e.g. truck, car
    manufacturer = models.CharField(maxlength=15)   #  e.g. Volkswagen, Isuzu
    theModel = models.CharField(maxlength=15)       #  e.g. Passat, Trooper
    year = models.IntegerField()
    
    def __str__(self):
        return repr(self.year) + ' ' + self.manufacturer + ' ' + self.theModel

class Route(models.Model):
    locFrom = models.CharField('Starting Location', maxlength=15)
    locTo   = models.CharField('Destination', maxlength=15) 

    def __str__(self):
        return self.locFrom + ' to ' + self.locTo

class Trip(models.Model):
    vehicle = models.ForeignKey(Vehicle)
    route   = models.ForeignKey(Route)

    def __str__(self):
        return repr(self.start) + ' ' + repr(self.route) + ' ' + repr(self.vehicle)
}}}

The models.py file is in the commuteTime app in the commute project
{{{
yoshiAshi:django$ ls -al commute
total 56
drwxr-xr-x   11 gerry  gerry   374 Apr 30 23:58 .
drwxr-xr-x    8 gerry  gerry   272 May  1 08:33 ..
-rw-r--r--    1 gerry  gerry     0 Apr 30 07:38 __init__.py
-rw-r--r--    1 gerry  gerry   157 Apr 30 08:07 __init__.pyc
drwxr-xr-x    9 gerry  gerry   306 May  1 08:33 commuteTime
drwxr-xr-x    3 gerry  gerry   102 Apr 30 23:32 db
-rw-r--r--    1 gerry  gerry   546 Apr 30 07:38 manage.py
-rw-r--r--    1 gerry  gerry  2828 Apr 30 23:06 settings.py
-rw-r--r--    1 gerry  gerry  1824 Apr 30 23:06 settings.pyc
-rw-r--r--    1 gerry  gerry   227 Apr 30 07:38 urls.py

yoshiAshi:django$ ls -al commute/commuteTime
total 48
drwxr-xr-x    9 gerry  gerry   306 May  1 08:33 .
drwxr-xr-x   11 gerry  gerry   374 Apr 30 23:58 ..
-rw-r--r--    1 gerry  gerry     0 Apr 30 08:10 __init__.py
-rw-r--r--    1 gerry  gerry   169 Apr 30 23:01 __init__.pyc
drwxr-xr-x    3 gerry  gerry   102 Apr 30 08:13 db
-rw-r--r--    1 gerry  gerry   876 May  1 08:13 models.py
-rw-r--r--    1 gerry  gerry  2312 May  1 08:13 models.pyc
-rw-r--r--    1 gerry  gerry    26 Apr 30 08:10 views.py
}}}

Testing the SQL generation give this
{{{
yoshiAshi:commute$ python manage.py sql commuteTime
BEGIN;
CREATE TABLE ""commuteTime_route"" (
    ""id"" integer NOT NULL PRIMARY KEY,
    ""locFrom"" varchar(15) NOT NULL,
    ""locTo"" varchar(15) NOT NULL
);
CREATE TABLE ""commuteTime_trip"" (
    ""id"" integer NOT NULL PRIMARY KEY,
    ""vehicle_id"" integer NOT NULL,
    ""route_id"" integer NOT NULL REFERENCES ""commuteTime_route"" (""id"")
);
CREATE TABLE ""commuteTime_vehicle"" (
    ""id"" integer NOT NULL PRIMARY KEY,
    ""type"" varchar(15) NOT NULL,
    ""manufacturer"" varchar(15) NOT NULL,
    ""theModel"" varchar(15) NOT NULL,
    ""year"" integer NOT NULL
);
COMMIT;
}}}
Note that the commuteTime_trip table does not have commuteTime_vehicle as a proper foreign key. We would expect
{{{
    ""vehicle_id"" integer NOT NULL REFERENCES ""commuteTime_vehicle"" (""id""),
}}}
but instead get
{{{
    ""vehicle_id"" integer NOT NULL,
}}}

== Work-Around ==

Misspelling ""Vehicle"" results in the correct behavior. For example if the Vehicle class and foreign key reference are replaced by
{{{
class Vahicle(models.Model):
    type = models.CharField(maxlength=15)           #  e.g. truck, car
    manufacturer = models.CharField(maxlength=15)   #  e.g. Volkswagen, Isuzu
    theModel = models.CharField(maxlength=15)       #  e.g. Passat, Trooper
    year = models.IntegerField()
    ...

class Trip(models.Model):
    vehicle = models.ForeignKey(Vahicle)
    route   = models.ForeignKey(Route)
    ...
}}}
the correct SQL is generated
{{{
yoshiAshi:commute$ python manage.py sql commuteTime
BEGIN;
CREATE TABLE ""commuteTime_route"" (
    ""id"" integer NOT NULL PRIMARY KEY,
    ""locFrom"" varchar(15) NOT NULL,
    ""locTo"" varchar(15) NOT NULL
);
CREATE TABLE ""commuteTime_vahicle"" (
    ""id"" integer NOT NULL PRIMARY KEY,
    ""type"" varchar(15) NOT NULL,
    ""manufacturer"" varchar(15) NOT NULL,
    ""theModel"" varchar(15) NOT NULL,
    ""year"" integer NOT NULL
);
CREATE TABLE ""commuteTime_trip"" (
    ""id"" integer NOT NULL PRIMARY KEY,
    ""vehicle_id"" integer NOT NULL REFERENCES ""commuteTime_vahicle"" (""id""),
    ""route_id"" integer NOT NULL REFERENCES ""commuteTime_route"" (""id"")
);
COMMIT;
}}}

I've experimented with different spellings: ""Ve"" gives the correct foreign key
definition, but ""Veh"" does not.

Weird.

= Hardware and Software Configuration =


Mac OS 10.4.9[[BR]]
python 2.3.5[[BR]]
django svn trunk revision 5127[[BR]]
Database: sqlite (for development server)

I started the discovery of this bug on another Mac running python 2.5, so I don't think it depends on the python version. I'll check later today, or maybe tonight, depending on when I get the time."		closed	Database layer (models, ORM)	dev		duplicate	foreignKey, spelling, SQL error		Accepted	1	0	0	0	0	0