python - if exists else 的简短写法

Question

我想做的是:

if myObject:  # (not None)
    attr = myObject.someAttr
else:
    attr = ''

并尽可能避免使用三元表达式。有没有类似的东西:

attr = myObject.someAttr || '' ? 

我正在考虑创建自己的函数，例如:

get_attr_or_default(instance,attr,default):
    if instance:
        return instance.get_attribute(attr)
    else:
        return default

但是听到 python 没有这方面的快捷方式，我会感到很惊讶。

综合:

我尝试了两种解决方案，结果如下:

class myClass(Models.model):
    myObject = model.foreignKey('AnotherClass')

class AnotherClass(Models.model):
    attribute = models.charField(max_length=100,default = '')


attr = myClass.myObject.attribute if myClass.myObject else '' # WORKED
attr = myClass.myObject and myClass.myObject.attribute # WORKED with NONE as result
attr = myClass.myObject.attribute or ''  # Raises an error (myObject doesn't have attribute attribute)
try: attr = myClass.myObject.attribute
except AttributeError: attr = ''  # Worked

感谢您的回答!

Answer 1

6.11. Conditional expressions

attr = myObject.someAttr if myObject else ""