How to fix AttributeError: 'bytes' object has no attribute 'encode' if using mysql?

Question

Django development server was running fine using mysql up to yesterday. But today I get the error AttributeError: 'bytes' object has no attribute 'encode'.

I created a new blank django instance by running django-admin startproject newProject. It runs with 'ENGINE': 'django.db.backends.sqlite3'. But produces same error when I change it to 'ENGINE': 'django.db.backends.mysql'

System specification:

os: manjaro linux
virtual environment python version: 3.6
Django version: 2.2
MariaDB version: 10.3.15-1

Have not updated any related package in last 3 days.

The error:

Watching for file changes with StatReloader
Performing system checks...

System check identified no issues (0 silenced).
Exception in thread django-main-thread:
Traceback (most recent call last):
  File "/usr/lib64/python3.6/threading.py", line 916, in _bootstrap_inner
    self.run()
  File "/usr/lib64/python3.6/threading.py", line 864, in run
    self._target(*self._args, **self._kwargs)
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/utils/autoreload.py", line 54, in wrapper
    fn(*args, **kwargs)
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/core/management/commands/runserver.py", line 120, in inner_run
    self.check_migrations()
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/core/management/base.py", line 453, in check_migrations
    executor = MigrationExecutor(connections[DEFAULT_DB_ALIAS])
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/migrations/executor.py", line 18, in __init__
    self.loader = MigrationLoader(self.connection)
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/migrations/loader.py", line 49, in __init__
    self.build_graph()
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/migrations/loader.py", line 212, in build_graph
    self.applied_migrations = recorder.applied_migrations()
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/migrations/recorder.py", line 73, in applied_migrations
    if self.has_table():
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/migrations/recorder.py", line 56, in has_table
    return self.Migration._meta.db_table in self.connection.introspection.table_names(self.connection.cursor())
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/backends/base/base.py", line 256, in cursor
    return self._cursor()
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/backends/base/base.py", line 233, in _cursor
    self.ensure_connection()
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/backends/base/base.py", line 217, in ensure_connection
    self.connect()
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/backends/base/base.py", line 197, in connect
    self.init_connection_state()
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 232, in init_connection_state
    if self.features.is_sql_auto_is_null_enabled:
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/utils/functional.py", line 80, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/backends/mysql/features.py", line 82, in is_sql_auto_is_null_enabled
    cursor.execute('SELECT @@SQL_AUTO_IS_NULL')
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/backends/utils.py", line 103, in execute
    sql = self.db.ops.last_executed_query(self.cursor, sql, params)
  File "/srv/http/python/env/env36/lib/python3.6/site-packages/django/db/backends/mysql/operations.py", line 147, in last_executed_query
    query = query.encode(errors='replace')
AttributeError: 'bytes' object has no attribute 'encode'

How do I fix this ?

Why does your traceback have query.encode() when the actual 2.2.2 Django release uses query.decode()? That entirely invalidates my diagnosis as I had mistakenly assumed I was looking at the same code by looking at the released version. You appear to have already altered your local Django source code, which also explains why the traceback puts the error at line 147 rather than the expected line 146. — Martijn Pieters
– Martijn Pieters, Commented Jun 23, 2019 at 15:06
Thank you for your help & time. I have confirmed my friend changed it while using my PC. I'm currently using if not isinstance(query, bytes): query = query.encode(errors='replace') If there are problems I will reinstall. Thanks again — Tuhin
– Tuhin, Commented Jun 25, 2019 at 16:55

Tuhin · Accepted Answer · 2019-06-23 13:36:55Z

3

Thank to Martijn, I have fixed this. In the source, stable 2.2 branch line 146 of django/db/backends/mysql/operations.py is

query = query.decode(errors='replace')

In my system path/to/virtualenv/django/db/backends/mysql/operations.py was like

# query = query.decode(errors='replace')
query = query.encode(errors='replace')

I changed it to

query = query.decode(errors='replace')
# query = query.encode(errors='replace')

It is working correctly now.

answered Jun 23, 2019 at 13:36

Tuhin

531 silver badge9 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Martijn Pieters Over a year ago

Right, so you really want to force a reinstall of Django, and everything else too if that’s been altered in-place: pip install —force-reinstall -r requirements.txt

Martijn Pieters Over a year ago

And that line was probably changed in an (I’ll-informed) attempt to try and make PyMySQL work, as per code.djangoproject.com/ticket/30380. In which case you’d want to add from django.utils.encoding import force_text At the top and then use query = force_string(query).

Collectives™ on Stack Overflow

How to fix AttributeError: 'bytes' object has no attribute 'encode' if using mysql?

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related