【从startproject开始的django源码学习】

在Django中，startproject是一个命令行工具，它用于创建新的Django项目。这个命令创建了一个新的项目目录，包含了Django的基础项目结构和文件。

以下是startproject命令的核心功能实现部分，这是一个简化的代码示例：

import os
import shutil
 
def create_project(project_name, directory=None):
    """
    创建一个新的Django项目。
    :param project_name: 项目名称
    :param directory: 项目创建的目录，如果未指定，则为当前目录
    """
    # 如果未指定目录，则在当前目录下创建项目
    if directory is None:
        directory = os.getcwd()
    
    project_directory = os.path.join(directory, project_name)
    if os.path.exists(project_directory):
        raise ValueError("项目目录已存在")
    
    os.mkdir(project_directory)
    
    # 初始化项目的文件结构
    manage_py_path = os.path.join(project_directory, 'manage.py')
    with open(manage_py_path, 'w') as file:
        file.write("#!/usr/bin/env python\n")
        file.write("import os\n")
        file.write("import sys\n\n")
        file.write("if __name__ == '__main__':\n")
        file.write("    os.environ.setdefault('DJANGO_SETTINGS_MODULE', '{}'.format(project_name))\n".format(project_name))
        file.write("    try:\n")
        file.write("        from django.core.management import execute_from_command_line\n")
        file.write("    except ImportError as exc:\n")
        file.write("        raise ImportError(exc.msg + 'Django project directory {project_name} does not exist.'.format(project_name=project_name))\n")
        file.write("    execute_from_command_line(sys.argv)\n")
 
    os.chmod(manage_py_path, 0o755)
    
    # 创建项目的初始settings.py文件
    settings_file_path = os.path.join(project_directory, '{project_name}/settings.py'.format(project_name=project_name))
    with open(settings_file_path, 'w') as file:
        file.write("from pathlib import Path\n\n")
        file.write("BASE_DIR = Path(__file__).resolve().parent.parent\n\n")
        file.write("SECRET_KEY = 'your-secret-key'\n")
        file.write("DEBUG = True\n")
        file.write("ALLOWED_HOSTS = []\n\n")
        file.write("INSTALLED_APPS = [\n")
        file.write("    'django.contrib.admin',\n")
        file.write("    'django.contrib.auth',\n")
        file.write("    'django.contrib.contenttypes',\n")
        file.write("    'django.contrib.ses