problems in using python

python

发布日期: 2017-10-25

文章字数: 461

阅读时长: 2 分

(声明，以下Q代表问题，A代表答案)

Q1: 安装mysql-python库报错，如下：

描述

  (python27) jockie:/usr/local/bin$ pip install mysql-python
  Collecting mysql-python
    Using cached MySQL-python-1.2.5.zip
      Complete output from command python setup.py egg_info:
      sh: mysql_config: command not found
      Traceback (most recent call last):
        File "<string>", line 1, in <module>
        File "/private/var/folders/yf/m8nhcn4x1vd1snmnykt7n89h0000gn/T/pip-build-sSaKtK/mysql-python/setup.py", line 17, in <module>
          metadata, options = get_config()
        File "setup_posix.py", line 43, in get_config
          libs = mysql_config("libs_r")
        File "setup_posix.py", line 25, in mysql_config
          raise EnvironmentError("%s not found" % (mysql_config.path,))
      EnvironmentError: mysql_config not found

      ----------------------------------------
  Command "python setup.py egg_info" failed with error code 1 in /private/var/folders/yf/m8nhcn4x1vd1snmnykt7n89h0000gn/T/pip-build-sSaKtK/mysql-python/

A1: 找不到mysql_config，原因mysql安装目录/usr/local/mysql/bin不在PATH中,临时解决方法：
```
  export PATH=$PATH:/usr/local/mysql/bin
```

Q2: import循环引用，导致ImportError，

描述：如下两个文件互相调用：

  #home/__init__.py
  from flask import Blueprint
  import app.home.views
  home = Blueprint('home', __name__)
  
  #home/views.py
  from . import home
  @home.route('/')
  def index():
      return '<h1 style="color:green">this is home!</h1>'

  Traceback (most recent call last):
    File "/Users/jockie/programs/micro_movie/manage.py", line 7, in <module>
      from app import app
    File "/Users/jockie/programs/micro_movie/app/__init__.py", line 8, in <module>
      from app.home import home as home_blueprint
    File "/Users/jockie/programs/micro_movie/app/home/__init__.py", line 9, in <module>
      import app.home.views
    File "/Users/jockie/programs/micro_movie/app/home/views.py", line 7, in <module>
      from . import home
  ImportError: cannot import name 'home'

A2: 程序执行的顺序是从上往下执行，所以要先定义home对象，再导入视图！修改__init__.py中import顺序
```
  #home/__init__.py
  from flask import Blueprint
  home = Blueprint('home', __name__)
  import app.home.views
```