list of dicts to list of chainmap dicts with unique keys

Question

How to convert this

l = [{'a':1}, {'b':2}, {'a':3}, {'b':4}]
   

to

 l_chained = [{'a':1, 'b':2}, {'a':3, 'b':4}]

I know how to fetch unique keys, but stuck with further implementation ChainMap just makes plain dictionary excluding l[2] and l[3]

UPDATE1

I use Mapping to pass it as ORM kwargs

user_data = [{'name':'John'}, {'lastname':'Doe'}]
user_data = {'name':'John', 'lastname':'Doe'}

user = User.create(**data1_chained)

User provides FK that must be passed to related model

courses_data = [{'title':'Python'}, {'paid':0}, {'title':'Kubernetes'}, {'paid':1}]

courses_data_chained = [{'title':'Python', 'paid':0}, {'title':'Kubernetes', 'paid':1}]
for c_d_c in  courses_data_chained:
     Course.create(**c_d_c, user=user)

length of data is dynamic so I have to check if it has duplicated keys and generate array of dicts and than create records.

UPDATE2 First attempt still provides non generic solution, because dictionaries must go in that order, but works for arrays of various lengths

def chainmap_unique(arr:List[Dict[str, Any]]):
    unique_keys:List[str] = [next(k for k in tuple(elem.keys())) for elem in arr]
    deque_arr:Deque = deque(arr)
    last_keys = []
    output = []
    container = []
    while deque_arr:
        key = next(k for k in tuple(deque_arr[0].keys()))
        if not key in last_keys:
            container.append(deque_arr[0])
            deque_arr.popleft()
            last_keys.append(key)
        else:
            if all([k in unique_keys for k in last_keys]):
                d = dict(ChainMap(*container))
                last_keys.clear()
                container.clear()
                output.append(d)
            else:
                continue
    else:
        d = dict(ChainMap(*container))
        last_keys.clear()
        container.clear()
        output.append(d)
    # assert result
    return output

l1 = [{'a':1}, {'b':2}, {'c':6},  {'a':3}, {'b':4},{'c':8}]

result1 = chainmap_unique(l1)

assert result1 == [{'c': 6, 'b': 2, 'a': 1}, {'c': 8, 'b': 4, 'a': 3}]

l2 =  [{'a':1}, {'b':2}, {'c':6}, {'d':9}, {'a':3}, {'b':4},{'c':8}, {'d':10}]

result2 = chainmap_unique(l2)

assert result2 == [{'d':9, 'c': 6, 'b': 2, 'a': 1}, {'d':10, 'c': 8, 'b': 4, 'a': 3}]

Answer 1

you should try something like this:

l = [{'a':1}, {'b':2}, {'a':3}, {'b':4}]
l_chained = list()

for a, b in zip(l[::2], l[1::2]):
    l_chained.append({**a, **b})