flask/django 动态查询表结构相同表名不同数据的Model实现方法

# -*-coding:utf-8class NewDynamicModel(object): """ 动态产生模型和表的对应关系模型 :param base_cls: 基类模型，虚类，如TemplateModel :param tb_name: 数据库中对应的表名， 如tb_test_2017 :return: Model class eg: ''' class TemplateModel(db.Model):  __abstract__ = True  id = db.Column(db.Integer(), autoincrement=True, primary_key=True)  name = db.Column(db.VARCHAR(32), nullable=False) Test_2017 = NewDynamicModel(TemplateModel, 'tb_test_2017') print Test_2017.query.all() ''' """ _instance = dict() def __new__(cls, base_cls, tb_name):  new_cls_name = "%s_To_%s" % (   base_cls.__name__, '_'.join(map(lambda x:x.capitalize(),tb_name.split('_'))))  if new_cls_name not in cls._instance:   model_cls = type(new_cls_name, (base_cls,),        {'__tablename__': tb_name})   cls._instance[new_cls_name] = model_cls  return cls._instance[new_cls_name]

class NewDynamicModel(object): """ 动态产生模型和表的对应关系模型 :param base_cls: 基类模型，虚类，如TemplateModel :param tb_name: 数据库中对应的表名， 如tb_test_2017 :return: Model class eg: ''' class TemplateModel(db.Model):  __abstract__ = True  id = db.Column(db.Integer(), autoincrement=True, primary_key=True)  name = db.Column(db.VARCHAR(32), nullable=False) Test_2017 = NewDynamicModel(TemplateModel, 'tb_test_2017') print Test_2017.query.all() ''' """ @staticmethod def get_import_codes(Model):  """  获取基类的import依赖  :param Model:  :return:  """  module = inspect.getmodule(Model)  all_codelines = inspect.getsourcelines(module)  import_codes = []  import_codes.append('# -*-coding:utf-8/n')  for i in all_codelines[0]:   match = re.search(r'[from]*[/w|/s]*import [/w|/s]*', i)   if match:    import_codes.append(i)  import_codes.extend(['/n', '/n'])  return import_codes @staticmethod def get_codes(Model, new_model_name, tb_name):  """  获取基类的实现代码  :param Model:  :param new_model_name:  :param tb_name:  :return:  """  codes = inspect.getsourcelines(Model)[0]  result = []  has_alias_tb_name = False  result.append(codes[0].replace(Model.__name__, new_model_name))  for line in codes[1:]:   match = re.search(r'/s+__tablename__/s+=/s+/'(?P<name>/w+)/'', line)   abstract = re.search(r'(?P<indent>/s+)__abstract__/s+=/s+', line)   if abstract:    del line    continue   if match:    name = match.groupdict()['name']    line = line.replace(name, tb_name)    has_alias_tb_name = True   result.append(line)  if not has_alias_tb_name:   result.append("%s__tablename__ = '%s'/n" % (' ', tb_name))  return result @staticmethod def create_new_module(module_name, codes):  """  创建新表映射类的module文件  :param module_name:  :param codes:  :return:  """  f_path = os.path.join(CURRENT_PATH, '_tmp/%s.py' % module_name)  fp = open(f_path, 'w')  for i in codes:   fp.write(i)  fp.close()  return import_module('sync_session.models._tmp.%s' % module_name) _instance = dict() def __new__(cls, base_cls, tb_name):  new_cls_name = "%s_To_%s" % (   base_cls.__name__, ''.join(map(lambda x: x.capitalize(), tb_name.split('_'))))  if tb_name not in engine.table_names():   raise TableNotExist  if new_cls_name not in cls._instance:   import_codes = cls.get_import_codes(base_cls)   class_codes = cls.get_codes(base_cls, new_cls_name, tb_name)   import_codes.extend(class_codes)   new_module_name = new_cls_name.lower()   new_module = cls.create_new_module(new_module_name, import_codes)   model_cls = getattr(new_module, new_cls_name)   cls._instance[new_cls_name] = model_cls  return cls._instance[new_cls_name]

# -*-coding:utf-8from django.db import modelsclass NewDynamicModel(object): """ 动态产生模型和表的对应关系模型 :param base_cls: 基类模型，虚类，如TemplateModel :param tb_name: 数据库中对应的表名， 如tb_test_2017 :return: Model class eg: ''' class TemplateModel(models.Model):  id = models.AutoField(primary_key=True)  name = models.CharField(max_length=50)  class Meta:   abstract = True Test_2017 = NewDynamicModel(TemplateModel, 'tb_test_2017') print Test_2017.objects.all() ''' """ _instance = dict() def __new__(cls, base_cls, tb_name):  new_cls_name = "%s_To_%s" % (   base_cls.__name__, '_'.join(map(lambda x:x.capitalize(),tb_name.split('_'))))  if new_cls_name not in cls._instance:   new_meta_cls = base_cls.Meta   new_meta_cls.db_table = tb_name   model_cls = type(new_cls_name, (base_cls,),        {'__tablename__': tb_name, 'Meta': new_meta_cls, '__module__': cls.__module__})   cls._instance[new_cls_name] = model_cls  return cls._instance[new_cls_name]