[utils] Implemented identifiers as parameters in utils.merge_list

This will allow each backend to supply its own list
of supported identifiers for the merge_list function.

netjsonconfig/utils.py

@@ -33,13 +33,13 @@ def merge_config(template, config):
    return result


def merge_list(list1, list2):
def merge_list(list1, list2, identifiers=['name', 'id']):
    """
    Merges ``list2`` on top of ``list1``.

    If both lists contain dictionaries which have keys like
    ``name`` or ``id`` of equal values, those dicts are merged
    (dicts in ``list2`` will override dicts in ``list1``).
    If both lists contain dictionaries which have keys specified
    in ``identifiers`` which have equal values, those dicts will
    be merged (dicts in ``list2`` will override dicts in ``list1``).
    The remaining elements will be summed in order to create a list
    which contains elements of both lists.

@@ -52,12 +52,14 @@ def merge_list(list1, list2):
    for list_ in [list1, list2]:
        container = dict_map['list{0}'.format(counter)]
        for el in list_:
            if isinstance(el, dict) and 'name' in el:
                key = el['name']
            elif isinstance(el, dict) and 'id' in el:
                key = el['id']
            else:
                key = id(el)
            # merge by internal python id by default
            key = id(el)
            # if el is a dict, merge by keys specified in ``identifiers``
            if isinstance(el, dict):
                for id_key in identifiers:
                    if id_key in el:
                        key = el[id_key]
                        break
            container[key] = deepcopy(el)
        counter += 1
    merged = merge_config(dict_map['list1'], dict_map['list2'])