Creating class instance properties from a dictionary?

Rizwan Kassim picture Rizwan Kassim · Oct 28, 2009 · Viewed 70.4k times · Source

I'm importing from a CSV and getting data roughly in the format

{ 'Field1' : 3000, 'Field2' : 6000, 'RandomField' : 5000 }

The names of the fields are dynamic. (Well, they're dynamic in that there might be more than Field1 and Field2, but I know Field1 and Field2 are always going to be there.

I'd like to be able to pass in this dictionary into my class allMyFields so that I can access the above data as properties.

class allMyFields:
    # I think I need to include these to allow hinting in Komodo. I think.
    self.Field1 = None
    self.Field2 = None

    def __init__(self,dictionary):
        for k,v in dictionary.items():
            self.k = v
            #of course, this doesn't work. I've ended up doing this instead
            #self.data[k] = v
            #but it's not the way I want to access the data.

q = { 'Field1' : 3000, 'Field2' : 6000, 'RandomField' : 5000 }
instance = allMyFields(q)
# Ideally I could do this.
print q.Field1

Any suggestions? As far as why -- I'd like to be able to take advantage of code hinting, and importing the data into a dictionary called data as I've been doing doesn't afford me any of that.

(Since the variable names aren't resolved till runtime, I'm still going to have to throw a bone to Komodo - I think the self.Field1 = None should be enough.)

So - how do I do what I want? Or am I barking up a poorly designed, non-python tree?

Answer

Stephan202 picture Stephan202 · Oct 28, 2009

You can use setattr (be careful though: not every string is a valid attribute name!):

>>> class AllMyFields:
...     def __init__(self, dictionary):
...         for k, v in dictionary.items():
...             setattr(self, k, v)
... 
>>> o = AllMyFields({'a': 1, 'b': 2})
>>> o.a
1

Edit: let me explain the difference between the above code and SilentGhost's answer. The above code snippet creates a class of which instance attributes are based on a given dictionary. SilentGhost's code creates a class whose class attributes are based on a given dictionary.

Depending on your specific situation either of these solutions may be more suitable. Do you plain to create one or more class instances? If the answer is one, you may as well skip object creation entirely and only construct the type (and thus go with SilentGhost's answer).