While applying some external module method to a class I need to be able to pass different pairs of arg = 'value' to the function, like:
Ad.nodes.get(id_ = '11974312')
How to pass dicts or tuples to the function, so that it recognises 'id_' (string) as id_ (argument) in
('id_', '11974312') (tuple) or {'id_':'11974312'} (dictionary) ?
Basically, I just need to get id_ out of 'id_'
For your reference, I am trying to use neomodel module for neo4j graph db.
To pass multiple arguments to a function, you use the * operator and ** operator as shown below.
def myfoo(*arg, **karg):
print arg, karg
The * operator pack all ordered argument in it, and the ** operator packs all unmatched key argument in it.
For example:
def myfoo(a, *arg):
return a, arg
myfoo(11,22,33)
>> (11, [22, 33])
myfoo(11)
>> (11, [])
For key argument it works the same way,
def myfoo(a=11, b=22, **kargs):
return a, b, kargs
myfoo(22, c=100, b=233)
>> (22, 233, {'c': 100})
(ref.)
You can unfold the positional argument of a function with a single asterisk * and unfold dictionaries as key/value pairs with two asterisks **. For example
def get(a, b, c=0):
print(a, b, c)
args = (1, 2)
kwargs = {'c': 3}
get(*args, **kwargs)
The Python Reference has details on this.
A more specific example for OP
If you have a function get(id_=None) with the keyword argument id_ you can use **some_dict to unfold the key/value pairs into keyword arguments. For example
In [1]: def get(id_=None):
...: print(id_)
...: # do something with id_ ...
...:
In [2]: get(**{'id_': 1})
1
In [3]: get(**{'id_': 2})
2
If instead you have a function get(id_) with the positional argument id_ you can use *some_iterable to unfold the values into positional arguments. You can also use **some_dict to unfold the key/value pairs as long as the keys exactly match the positional arguments. For example
In [4]: def get(id_):
...: print(id_)
...: # do something with id_ ...
...:
In [5]: get(*(1,))
1
In [6]: get(*(2,))
2
In [7]: get(**{'id_': 3})
3
In [8]: # this will fail because `id` is not the argument, `id_` is
In [9]: get(**{'id': 4})
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-9-922e10531f8a> in <module>
----> 1 get(**{'id': 4})
TypeError: get() got an unexpected keyword argument 'id'
