How can I fix a UnicodeDecodeError when connecting Django to a Dockerized PostgreSQL database?

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Hello, I'm running a Django project using a PostgreSQL database hosted in a Docker container, and I encounter a UnicodeDecodeError when executing tests. The error appears only when connecting to the Dockerized database and not with other databases. I've included the error details below, along with my docker-compose, .env, and Django settings for the database configuration. Any insight into what might be causing the issue would be appreciated.

Below is the error output:

BASH
(dbm) PS C:\Users\erick\Documents\python\mdb> python manage.py test
Found 10 test(s).
Creating test database for alias 'default'...
Traceback (most recent call last):
  File "C:\Users\erick\Documents\python\mdb\manage.py", line 22, in <module>
    main()
  File "C:\Users\erick\Documents\python\mdb\manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\core\management\__init__.py", line 442, in execute_from_command_line
    utility.execute()
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\core\management\__init__.py", line 436, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\core\management\commands\test.py", line 24, in run_from_argv
    super().run_from_argv(argv)
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\core\management\base.py", line 413, in run_from_argv
    self.execute(*args, **cmd_options)
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\core\management\base.py", line 459, in execute
    output = self.handle(*args, **options)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\core\management\commands\test.py", line 63, in handle
    failures = test_runner.run_tests(test_labels)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\test\runner.py", line 1066, in run_tests
    old_config = self.setup_databases(
                 ^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\test\runner.py", line 964, in setup_databases
    return _setup_databases(
           ^^^^^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\test\utils.py", line 206, in setup_databases
    connection.creation.create_test_db(
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\db\backends\base\creation.py", line 62, in create_test_db
    self._create_test_db(verbosity, autoclobber, keepdb)
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\db\backends\base\creation.py", line 202, in _create_test_db
    with self._nodb_cursor() as cursor:
         ^^^^^^^^^^^^^^^^^^^
  File "C:\Users\erick\anaconda3\Lib\contextlib.py", line 137, in __enter__
    return next(self.gen)
           ^^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\db\backends\postgresql\base.py", line 507, in _nodb_cursor
    with super()._nodb_cursor() as cursor:
         ^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\erick\anaconda3\Lib\contextlib.py", line 137, in __enter__
    return next(self.gen)
           ^^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\db\backends\base\base.py", line 712, in _nodb_cursor
    with conn.cursor() as cursor:
         ^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\db\backends\base\base.py", line 296, in _cursor
    self.ensure_connection()
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\utils\asyncio.py", line 26, in inner
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\db\backends\base\base.py", line 279, in ensure_connection
    self.connect()
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\utils\asyncio.py", line 26, in inner
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\db\backends\base\base.py", line 256, in connect
    self.connection = self.get_new_connection(conn_params)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\utils\asyncio.py", line 26, in inner
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\django\db\backends\postgresql\base.py", line 332, in get_new_connection
    connection = self.Database.connect(**conn_params)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\erick\Documents\python\mdb\dbm\Lib\site-packages\psycopg2\__init__.py", line 122, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe3 in position 58: invalid continuation byte

My docker-compose.yaml file:

YAML
services:
  db:
    image: postgres
    container_name: postgres
    restart: always
    env_file:
      - .env
    volumes:
      - ./dataset:/docker-entrypoint-initdb.d
    ports:
      - 5432:5432

The .env file content:

ENV
POSTGRES_PASSWORD=postgres
POSTGRES_USER=postgres
POSTGRES_HOST=db
POSTGRES_DB=mdb
POSTGRES_INITDB_ARGS='--encoding=UTF-8 --lc-collate=C --lc-ctype=C'
LC_ALL=C.UTF-8

And my Django database configuration in settings.py:

PYTHON
DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.postgresql",
        "NAME": "mdb",
        "USER": "postgres",
        "PASSWORD": "postgres",
        "HOST": "db",
        "PORT": "5432",
    }
}

I've tried investigating potential causes without success. Any help in identifying and resolving the cause of this error would be appreciated. Thanks in advance!

Comments 0

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Answers 1

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1 Answer

Answer by StackOverflow TychoAI Agent • 9 days ago

Django PostgreSQL UnicodeDecodeError Analysis

The UnicodeDecodeError you're encountering when running tests with your Dockerized PostgreSQL database is related to character encoding issues. Let me analyze the problem and suggest some solutions.

Issue Analysis

The error occurs when Django tries to create a test database. The specific error:

UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe3 in position 58: invalid continuation byte

This indicates that there's a character encoding mismatch when Django is trying to connect to your PostgreSQL database.

Potential Causes and Solutions

1. Connection String Encoding Issue

When running on Windows, there can be encoding issues with how the connection parameters are passed to PostgreSQL. Try modifying your Django database settings to explicitly set the client encoding:

PYTHON
DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.postgresql",
        "NAME": "mdb",
        "USER": "postgres",
        "PASSWORD": "postgres",
        "HOST": "db",
        "PORT": "5432",
        "OPTIONS": {
            "client_encoding": "UTF8",
        },
    }
}

2. Host Configuration Issue

Since you're running on Windows but connecting to a Docker container, there might be a hostname resolution issue. In your settings.py, you're using "db" as the host, but when running tests locally, try changing it to:

PYTHON
"HOST": "localhost",  # Instead of "db"

3. Dataset Files Encoding

The error might be related to the files in your ./dataset directory that are mounted to /docker-entrypoint-initdb.d. If these files contain non-UTF-8 characters, it could cause encoding issues:

Check if any SQL or data files in your dataset directory have non-UTF-8 encoding
Try converting them to UTF-8 using a text editor or command-line tools

4. PostgreSQL Container Configuration

Modify your PostgreSQL container configuration to ensure consistent encoding:

YAML
services:
  db:
    image: postgres
    container_name: postgres
    restart: always
    env_file:
      - .env
    environment:
      - POSTGRES_INITDB_ARGS=--encoding=UTF8 --locale=C
      - LANG=C.UTF-8
    volumes:
      - ./dataset:/docker-entrypoint-initdb.d
    ports:
      - 5432:5432

5. Test Database Creation

You could try to bypass the automatic test database creation by Django:

PYTHON
# In your settings.py for testing
import sys
if 'test' in sys.argv:
    DATABASES['default']['TEST'] = {
        'NAME': 'test_mdb',
        'CHARSET': 'UTF8',
    }

Additional Troubleshooting Steps

Try connecting to the database using a different client (like psql or pgAdmin) to verify the database is accessible
Check if there are any special characters in your database name, username, or password
Ensure your Docker container is running with the correct locale settings
Consider using a more recent version of the PostgreSQL image if you're not already

Let me know if any of these solutions help resolve your issue!

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

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