详解Flask前后端分离项目案例

app = Flask(__name__, static_folder='views/statics', static_url_path='/static', template_folder="templates")

@property
  def static_url_path(self):
    """The URL prefix that the static route will be accessible from.

    If it was not configured during init, it is derived from
    :attr:`static_folder`.
    """
    if self._static_url_path is not None:
      return self._static_url_path

    if self.static_folder is not None:
      basename = os.path.basename(self.static_folder)
      return ("/" + basename).rstrip("/")

  @static_url_path.setter
  def static_url_path(self, value):
    if value is not None:
      value = value.rstrip("/")

    self._static_url_path = value

from flask import Flask

app = Flask(__name__)

from werkzeug.routing import BaseConverter

class RegexUrl(BaseConverter):
  # 指定匹配参数时的正则表达式
  # 如: # regex = '\d{6}'
  def __init__(self, url_map, regex):
    """
    :param url_map: flask会自动传递该参数
    :param regex: 自定义的匹配规则
    """
    super(RegexUrl, self).__init__(url_map)
    self.regex = regex
  
  # 在对应的试图函数之前调用
  # 从url中提取出参数之后，会先调用to_python
  # 会把提取出的值作为参数传递给to_pthon在返回给对应的试图
  def to_python(self, value):
    """可以在这里做一些参数的类型转换"""
    return value
  
  # 调用url_for时会被调用, 用来处理url反向解析时url参数处理
 # 返回值用来拼接url
  def to_url(self, value):
    """对接收到参数做一些过滤等"""
    return value
    
# 将自定义路由转换器类添加到转换器字典中
app.url_map.converters['re'] = RegexUrl


# 案例
@app.route('/user/<re("[a-z]{3}"):id>')
def hello(id):
  return f'hello {id}'


if __name__ == '__main__':
  app.run(debug=True)

@app.errorhandler(Exception)
def framework_error(e):
  if isinstance(e, APIException):
    return e
  elif isinstance(e, HTTPException):
    code = e.code
    msg = e.description
    error_code = 1007
    return APIException(msg, code, error_code)

  else:
    if not current_app.config['DEBUG']:
      return ServerError()
    else:
      raise e

from datetime import date
from flask import Flask as _Flask
from flask.json import JSONEncoder as _JSONEncoder

class JSONEncoder(_JSONEncoder):
  """
  重写json序列化，使得模型类的可序列化
  """
  def default(self, o):
    if hasattr(o, 'keys') and hasattr(o, '__getitem__'):
      return dict(o)
    if isinstance(o, date):
      return o.strftime('%Y-%m-%d')
    
   super(JSONEncoder, self).default(o)
    

# 需要将重写的类绑定到应用程序中
class Flask(_Flask):
  json_encoder = JSONEncoder

class User(Base):
  id = Column(Integer, primary_key=True)
  email = Column(String(24), unique=True, nullable=False)
  nickname = Column(String(24), unique=True)
  auth = Column(SmallInteger, default=1)
  _password = Column('password', String(100))
  
  def keys(self):
    return ['id', 'email', 'nickname', 'auth']
  
  def __getitem__(self, item):
    return getattr(self, item)

class Book(Base):
  id = Column(Integer, primary_key=True, autoincrement=True)
  title = Column(String(50), nullable=False)
  author = Column(String(30), default='未名')
  binding = Column(String(20))
  publisher = Column(String(50))
  price = Column(String(20))
  pages = Column(Integer)
  pubdate = Column(String(20))
  isbn = Column(String(15), nullable=False, unique=True)
  summary = Column(String(1000))
  image = Column(String(50))
 
  # orm实例化对象, 字段需要写在构造函数中，这样每个实例对象都会有自己的一份，删除增加都不会互相影响
  @orm.reconstructor
  def __init__(self):
    self.fields = ['id', 'title', 'author', 'binding',
            'publisher', 'price', 'pages', 'pubdate',
            'isbn', 'summary', 'image']
    
  def keys(self):
    return self.fields if hasattr(self, 'fields') else []
  
  def hide(self, *keys):
    for key in keys:
      self.fields.remove(key)
    return self
  
  def append(self, *keys):
    for key in keys:
      self.fields.append(key)
    return self


@api.route('/search')
def search():
  books = Book.query.filter().all() # 根据某些条件搜索的
  books = [book.hide('summary') for book in books]
  return jsonify(books)
  
  
@api,route('/<isbn>/detail')
def detail(isbn):
  book = Book.query.filter_by(isbn=isbn).first_or_404()
  return jsonify(book)

str2obj = {}
level2str = {}


def iteritems(d, *args, **kwargs):
  return iter(d.items(*args, **kwargs))


def _find_scope_group():
  for _name, obj in iteritems(globals()):
    try:
      is_scope_obj = issubclass(obj, BaseScope)
    except TypeError:
      is_scope_obj = False
    if not is_scope_obj or obj.level < 1:
      continue

    old_obj = str2obj.get(_name, None)
    if old_obj is not None and issubclass(obj, old_obj):
      continue
    str2obj[_name] = obj
    level2str[obj.level] = _name


# 模仿flask exceptions 预加载各个异常类的方式，将用户组自动加载进内存
_find_scope_group()
del _find_scope_group