Set attributes from dictionary in python

Question

Is it possible to create an object from a dictionary in python in such a way that each key is an attribute of that object?

Something like this:

 dict = { 'name': 'Oscar', 'lastName': 'Reyes', 'age':32 }

 e = Employee( dict ) 
 print e.name # Oscar 
 print e.age + 10 # 42 

I think it would be pretty much the inverse of this question: Python dictionary from an object's fields

Answer 1

Sure, something like this:

class Employee(object):
    def __init__(self, initial_data):
        for key in initial_data:
            setattr(self, key, initial_data[key])

Update

As Brent Nash suggests, you can make this more flexible by allowing keyword arguments as well:

class Employee(object):
    def __init__(self, *initial_data, **kwargs):
        for dictionary in initial_data:
            for key in dictionary:
                setattr(self, key, dictionary[key])
        for key in kwargs:
            setattr(self, key, kwargs[key])

Then you can call it like this:

e = Employee({"name": "abc", "age": 32})

or like this:

e = Employee(name="abc", age=32)

or even like this:

employee_template = {"role": "minion"}
e = Employee(employee_template, name="abc", age=32)

Answer 2

You can access the attributes of an object with __dict__, and call the update method on it:

>>> class Employee(object):
...     def __init__(self, _dict):
...         self.__dict__.update(_dict)
... 


>>> dict = { 'name': 'Oscar', 'lastName': 'Reyes', 'age':32 }

>>> e = Employee(dict)

>>> e.name
'Oscar'

>>> e.age
32

Answer 3

I think that answer using settattr are the way to go if you really need to support dict.

But if Employee object is just a structure which you can access with dot syntax (.name) instead of dict syntax (['name']), you can use namedtuple like this:

from collections import namedtuple

Employee = namedtuple('Employee', 'name age')
e = Employee('noname01', 6)
print e
#>> Employee(name='noname01', age=6)

# create Employee from dictionary
d = {'name': 'noname02', 'age': 7}
e = Employee(**d)
print e
#>> Employee(name='noname02', age=7)
print e._asdict()
#>> {'age': 7, 'name': 'noname02'}

You do have _asdict() method to access all properties as dictionary, but you cannot add additional attributes later, only during the construction.

Answer 4

Setting attributes in this way is almost certainly not the best way to solve a problem. Either:

1. You know what all the fields should be ahead of time. In that case, you can set all the attributes explicitly. This would look like

   class Employee(object):
       def __init__(self, name, last_name, age):
           self.name = name
           self.last_name = last_name
           self.age = age
   
   
   d = {'name': 'Oscar', 'last_name': 'Reyes', 'age':32 }
   e = Employee(**d) 
   
   
   print e.name # Oscar 
   print e.age + 10 # 42 
   

   or

2. You don't know what all the fields should be ahead of time. In this case, you should store the data as a dict instead of polluting an objects namespace. Attributes are for static access. This case would look like

   class Employee(object):
       def __init__(self, data):
           self.data = data
   
   
   d = {'name': 'Oscar', 'last_name': 'Reyes', 'age':32 }
   e = Employee(d) 
   
   
   print e.data['name'] # Oscar 
   print e.data['age'] + 10 # 42 
   

---

Another solution that is basically equivalent to case 1 is to use a collections.namedtuple. See van's answer for how to implement that.