Dynamically generate getter methods for a repository based on the name of fields

repository_method_generator.py

from typing import List, Callable, Iterator, Tuple

LOGICAL_SEPARATORS = ["and", "or"]
OPERATORS = ["lt", "gt", "not", "in", "none"]
OPERATORS_MAPPING = {"=": "=", "lt": "<", "gt": ">", "lte": "<=", "gte": ">=", "not": "!=", "none": "is None",
                     "is": "is"}

# TODO: Add docstrings
# After first generation, add method to the repository class for further calling.
def _generate_method(method_name: str) -> Callable:
    zip_iterator = _process_getter(method_name.split("_"))

    def the_method(*args):
        res = []
        l = len(args)
        it = iter(args)
        for param, operation, logical in zip_iterator:
            try:
                value = next(it)
                if isinstance(value, bool):  # we must base on type of param
                    operation = "is"
                res.append(f"{param} {OPERATORS_MAPPING[operation]} {value}")
            except StopIteration:
                raise TypeError(f"{method_name} is missing 1 required positional argument: '{param}'")
        return ", ".join(res)

    return the_method


def _process_getter(parts: List[str]) -> Iterator[Tuple[str, str, str]]:
    current_name = None
    operators = []
    logicals = []
    names = []
    last_logical = None
    operation = None
    for name in parts:
        if not current_name:
            current_name = name
            continue
        if name in OPERATORS:
            operation = name
        elif name in LOGICAL_SEPARATORS:
            operators.append(operation or "=")
            logicals.append(last_logical or "and")
            names.append(current_name)
            last_logical = name
            current_name = None
        else:
            current_name = f"{current_name}_{name}"
    operators.append(operation or "=")
    logicals.append(last_logical or "and")
    names.append(current_name)
    return zip(names, operators, logicals)


def test():
    methods = {"username_and_password": ("mouhamad", "CTSM@@Ngui"), "value_gt_and_name_not_and_age_lt": (2, "Beep", 63), "last_change_or_password_expired": ("2019-05-21", False), "age_gt_and_is_enabled_and_locked": (18, False, False)}
    # for m in methods:
    #     r = _process_getter(m.split("_"))
    #     r = [str(e) for e in r]
    #     print(f"{m} -> {r}")
    for m, values in methods.items():
        f = _generate_method(m)
        res = f(*values)
        print(f"{m} -> {res}")


if __name__ == "__main__":
    test()