Unfinished: dict_from_list_adaptor to convert easily from a list to a dict related to https://groups.google.com/forum/#!msg/ansible-project/TYbORkOM6Dw/5lusNmTIDzUJ

dict_from_list_adaptor

from collections import Counter

def dict_from_list_adaptor(key, _list, key_name=None, results_names=None, find_first=False):
    '''Given a list-flattened dict, do a key value retrieval
       
       Imagine a dictionary where every entry was {word: dictword, def: ditdef} instead of {dictword: dictdef}
       eg.  list_flattened_dict=[{word: apple, def: 'fruit...', noun: True},{word: ape, def: 'mamal of genus...', noun: True}]
       We have to loop over entries in order to extract the definition turning a constant time
       hash lookup of a dict into a linear time array scan for a list.
       Basically, our data is stored in the wrong datastructure and we need an adaptor.
       
       @key: key for which we wish to extract the value
       @_list: list of dict entries to scan.  We search for 'key' in the values of each dict entry of _list.
       @key_name: If defined, only search for the requested key as the value 
                  for the list key of this name.
       @results_names: If defined, only return _list values whose keys are in resutls_names,
                      otherwise, return the entire matching entry in list.
                  
       @returns: a dict which is a subset of the matching item (list entry) with keys in results_names, 
                 If results_names=None all key-value pairs besides the requested key are returned.
       @throws: NonUniqueKeyException if the key is found more than once
       @throws: NonUniqueKeyException when requesting a key that is the value in multiple
       fields in the flattened dict.  In the example above, the entry word: True would be a problem because 
       if we search for key=True we find it in multiple values.  Using key_name avoids this.
       '''
    def return_results(key, list_entry_dict, results_names):
        result=[]
        for _key in list_entry_dict.keys():
            # add the key-value pair to the results
             if _key != key:
                result.append({_key: list_entry_dict[_key]})
        return result
        
    results=[]
    for item in _list:
        if key_name:
            if item[key_name] == key:
                results.append(return_results(key, item, results_names))
                if find_first:
                    return results[0]
        else:
            if key in item.values():
                if Counter(item.values()).get(key) > 1:
                    raise Exception("NonUniqueKeysException", "Found multiple values for {} in {}".format(key,item))
                results.append(return_results(key, item, results_names))
                if find_first:
                    return results[0]
    if len(results) > 1:
        raise Exception("NonUniqueKeysException", "Found multiple values for {} in {}".format(key,results))
    if results:
        return results[0]
    else:
        return None