解決Django使用mysqlclient連接MySQL，而無法pip install mysqlclient 問題

解決Django使用mysqlclient連接MySQL，而無法pip install mysqlclient 問題

詳情：
    該問題主要出現在Django在Ubuntu系統中連接MySQL時會報錯：
    
        django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module.
        Did you install mysqlclient?
        
    然而，ubuntu安裝mysqlclient時會出現很多麻煩的問題

策略：使用pymysql連接MySQL

• 安裝pymysql

pip3 install pymysql

• 修改項目的__init__.py

import pymysql
pymysql.install_as_MySQLdb()

此時運行項目，會保錯：

......
File "/home/brightxu/Django/WGApps/venv/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 36, in <module>
    raise ImproperlyConfigured('mysqlclient 1.3.13 or newer is required; you have %s.' % Database.__version__)
django.core.exceptions.ImproperlyConfigured: mysqlclient 1.3.13 or newer is required; you have 0.9.3.

主要是pymysql與mysqlclient版本不一致的問題

• 修改環境

根據錯誤提示，打開文件venv/lib/python3.6/site-packages/django/db/backends/mysql/base.py ，找到第36行代碼，將34 ～ 36 行的代碼註釋掉：

# version = Database.version_info
# if version < (1, 3, 13):
#     raise ImproperlyConfigured('mysqlclient 1.3.13 or newer is required; you have %s.' % Database.__version__)

然後還會保錯：

......
File "/home/brightxu/Django/WGApps/venv/lib/python3.6/site-packages/django/db/backends/mysql/operations.py", line 146, in last_executed_query
    query = query.decode(errors='replace')
AttributeError: 'str' object has no attribute 'decode'

根據錯誤提示，打開文件venv/lib/python3.6/site-packages/django/db/backends/mysql/operations.py ，找到第146行代碼，將145和 146 行的代碼註釋掉：

        # if query is not None:
        #     query = query.decode(errors='replace')

• 然後就可以愉快的玩耍了