Django 3.2+：在 MySQL 表中实现区分大小写的字符串比较

Question

Django 文档（3.2 到 4.0）指出：

In MySQL, a database table’s collation determines whether string comparisons (such as the expression and substring of this function) are case-sensitive. Comparisons are case-insensitive by default.

从 3.2 开始，提到现在可以在 CharField 级别定义要使用的排序规则： https://docs.djangoproject.com/en/3.2/ref/databases/#collation-settings

但我找不到我应该为 db_collation 使用什么值来为给定的 CharField 启用区分大小写的字符串比较：

case_sensitive_collation = ???    
name = models.CharField(max_length=50, db_collation=case_sensitive_collation)

刚刚发现这个要点恰恰相反： CreateCollation and db_collation to implement a case-insensitive Charfield with Postgres > 12 https://gist.github.com/hleroy/2f3c6b00f284180da10ed9d20bf9240a

有人可以帮我吗？

编辑：这是 SHOW CREATE TABLE。目标是让字段 pieces 区分大小写：

MariaDB [FormApp_db]> show create table puzzles_puzzlepieces; 

    +----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
    | Table                | Create Table                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
    +----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
    | puzzles_puzzlepieces | CREATE TABLE `puzzles_puzzlepieces` (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      `pieces` varchar(255) NOT NULL,
      `uncolored_id` int(11) DEFAULT NULL,
      `piece_setup_id` int(11) DEFAULT NULL,
      PRIMARY KEY (`id`),
      UNIQUE KEY `pieces` (`pieces`),
      KEY `puzzles_puzzlepieces_uncolored_id_8afb6603_fk_puzzles_p` (`uncolored_id`),
      CONSTRAINT `puzzles_puzzlepieces_uncolored_id_8afb6603_fk_puzzles_p` FOREIGN KEY (`uncolored_id`) REFERENCES `puzzles_puzzlepieces` (`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=3094388 DEFAULT CHARSET=utf8mb4 |
    +----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
    1 row in set (0.003 sec)

和生成的SELECT:

>>> x = PuzzlePieces.objects.all()
>>> x[0]
SELECT `puzzles_puzzlepieces`.`id`,
       `puzzles_puzzlepieces`.`pieces`,
       `puzzles_puzzlepieces`.`uncolored_id`,
       `puzzles_puzzlepieces`.`piece_setup_id`
  FROM `puzzles_puzzlepieces`
 LIMIT 1

Execution time: 0.002870s [Database: default]

Answer 1

为了验证@rickjames 提出的解决方案，我将在此处记录答案的实现：

在settings.py中：

if app_version == 'prod':
    DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.mysql',
            'OPTIONS': {
                'read_default_file': '/home/src/my.cnf'
            }
        }
    }
    DB_IS_MYSQL = True
else:
    DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.sqlite3',
            'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
        }
    }
    DB_IS_MYSQL = False

MYSQL_SENSITIVE_COLLATION = 'ascii_bin'  
DB_CASE_SENSITIVE_COLLATION  = {'db_collation': MYSQL_SENSITIVE_COLLATION} if DB_IS_MYSQL else {}
# Use: 
# from django.conf import settings
# pieces = models.CharField(max_length=255, default='empty', unique=True, **settings.DB_CASE_SENSITIVE_COLLATION)

在model.py中：

name = models.CharField(max_length=50, **settings.DB_CASE_SENSITIVE_COLLATION)

Django 3.2+：在 MySQL 表中实现区分大小写的字符串比较

Django 3.2+: implementing case-sensitive string comparisons within MySQL tables

mysql

django

collation

case-sensitive

django-models