Model object save gives Warning: Data truncated for column

[Chen Xu]

Hi Everyone,

I am new to Django, I am currently converting my site from php to Django. I have already have my database (all the tables) setup when I wrote in php; now when I convert to Django, I am basically matching each column with the existing column. After I finished doing this, I try to create an object, and doing a <object>.save()  gives me Warning: Data truncated for column '<some column>'. However, I checked, the length of my string did not excess the limit.

Could anyone help?

Thanks

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⚡ Chen Xu ⚡

[Bill Freeman]

Does the field in question have "max_length" specified (assuming that it is a character field or a sub class)?  Does introspecting the database with the database's tools indicate that the corresponding field has that size?  Was the database created using Django's syncdb, or are you attempting to use an existing database.  Which database engine are you using (e,g.; PostgreSQL, MySQL, etc. - different people will have insights into different back ends)?  Is a stack trace printed - if so, provide it for us?  At least, what is the exact text of the error message?

Bill

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[Chen Xu]

I am using my existing mysql db. I found out that if I have an enum and try to insert a value not present in the enum this error will occur.

However, my problem occurs on a TimeField. I created this field using phpMyAdmin, it is a timestamp, and default is current time. Therefore, I did the following in my Django model:

message_create_time = models.TimeField(auto_now_add=True)

When I create an object, and save, it gives me:

Traceback (most recent call last):

  File "<console>", line 1, in <module>

  File "/Library/Python/2.7/site-packages/django/db/models/base.py", line 463, in save

    self.save_base(using=using, force_insert=force_insert, force_update=force_update)

  File "/Library/Python/2.7/site-packages/django/db/models/base.py", line 551, in save_base

    result = manager._insert([self], fields=fields, return_id=update_pk, using=using, raw=raw)

  File "/Library/Python/2.7/site-packages/django/db/models/manager.py", line 203, in _insert

    return insert_query(self.model, objs, fields, **kwargs)

  File "/Library/Python/2.7/site-packages/django/db/models/query.py", line 1593, in insert_query

    return query.get_compiler(using=using).execute_sql(return_id)

  File "/Library/Python/2.7/site-packages/django/db/models/sql/compiler.py", line 912, in execute_sql

    cursor.execute(sql, params)

  File "/Library/Python/2.7/site-packages/django/db/backends/util.py", line 40, in execute

    return self.cursor.execute(sql, params)

  File "/Library/Python/2.7/site-packages/django/db/backends/mysql/base.py", line 114, in execute

    return self.cursor.execute(query, args)

  File "/Library/Python/2.7/site-packages/MySQL_python-1.2.4-py2.7-macosx-10.8-intel.egg/MySQLdb/cursors.py", line 203, in execute

    if not self._defer_warnings: self._warning_check()

  File "/Library/Python/2.7/site-packages/MySQL_python-1.2.4-py2.7-macosx-10.8-intel.egg/MySQLdb/cursors.py", line 117, in _warning_check

    warn(w[-1], self.Warning, 3)

Warning: Data truncated for column 'message_create_time' at row 1

However if I change it to :

message_create_time = models.DateTimeField()

It works perfectly.

Any ideas?

Thanks in advance

--
⚡ Chen Xu ⚡

[Bill Freeman]

Not being a MySQL expert, I'll still have a guess.  The TimeField just represents the time of day, with no notion of what day, see http://docs.python.org/2.7/library/datetime.html#time-objects .  The term "timestamp", on the other hand, means to me a point in time in the more grand sense, such as the integer number of seconds since the "epoch", and thus embodies date and time.  So if the "timestamp" in your database is something from which you can figure out when something happened, including on which day it happened, then DateTimeField is the correct one to use.

By the way, Django provides a feature to "introspect" an existing database and to compose models for it.  I'll bet that it suggests the DataTimeField.

Bill

[Chen Xu]

Yes, this sound reasonable, and I verified it. You are absolutely correct.

Thanks for your help

Best regards