BooleanDictFilter

Sometimes it is necessary to be able to make a filter which is a string, that evaluates the contents of a dictionary object. Sure we could write that in Python and use eval, but that would be considered a security risk. Instead we use a conditional boolean string, which can handle the comparisons we need.

Operands

Features

Other then typical boolean operations and evaluations. I added the following evaluators to the flow, to make things a bit simpler.

• contains if the value of key is a string, and contains the string specified, this returns true. If key is not a string this returns false.
• anyof if the value of key is any of one the values specified in the list, then this returns true. Useful to remove a bunch of OR statements.
• noneof if the value of key is not in the list of values specified, then this returns true.

If any of the key does not exist in the dictionary, then result is false. However this is dependent on the key being reached. For instance:

(name == "John") or (nonexistentkey == "X")

Would be true, if the key "name" was "John" in the given dictionary.

Installation

To install, run:

pip install booleanDictFilter

Examples

Allows for testing a single, or group of dictionaries against a text defined filter.

from BooleanDictFilter import BooleanDictFilter

filter_str = "(anyof(role, ['admin', 'moderator']) and age >= 30)"
bf = BooleanDictFilter.BooleanDictFilter(filter_str)
print (bf.evaluate({"role": "admin", "age": 35, "status": "active", "name": "John"})) # True
print (bf.evaluate({"role": "user", "age":34, "status": "active", "name": "June"})) # False

The same filter can be used to evaluate a list of dictionaries, returning only those dictionaries which passed the evaluation:

from BooleanDictFilter import BooleanDictFilter
filter_str = "(anyof(role, ['admin', 'moderator']) and age >= 30)"  
bf = BooleanDictFilter.BooleanDictFilter(filter_str)
data_list = [  
	{"role": "admin", "age": 35, "status": "active", "name": "John"},
	{"role": "user", "age":34, "status": "active", "name": "June"}
]
filtered_data = bf.filter_dicts(data_list)  
for item in filtered_data:  
    print(item)

Result:

[  
	{"role": "admin", "age": 35, "status": "active", "name": "John"}
]

License

This project is licensed under the MIT License.