I want to replace the inner maps that match the supplied source_id and replace them with a default value of %{"source" => "", "value" => ""}
If the matched map was is a list, then it should be removed (if it‘s a top level item in that list).
So if I call cleanup(data, "my-id"), the expected output should be:
Not sure if this is elegant, but this one way of doing it
defmodule Example do
def cleanup(data, source) when is_map(data) do
if filter?(data, source) do
%{"source" => "", "value" => ""}
else
Map.new(data, fn {key, value} ->
{key, cleanup(value, source)}
end)
end
end
def cleanup([hd | tail], source) do
list = if filter?(hd, source), do: tail, else: [hd | tail]
Enum.map(list, &cleanup(&1, source))
end
def cleanup(data, _source), do: data
defp filter?(data, source), do: match?(%{"source" => ^source}, data)
end
arbitrary keys (Most of the time I’d prefer %{key: "foo", value: "bar"} over %{foo: "bar"})
maps may occur in lists and as single item (why not lists of one instead?)
nested structure, most of the times a flat structure is easier to handle
Its impossible to say if that would be better not knowing what you are doing. But I found that thinking twice about the data structures can lead to way simpler code.
defmodule Cleanup do
def cleanup(data, source_id) do
case data do
%{"source" => ^source_id} ->
%{"source" => "", "value" => ""}
%{} ->
Map.new(data, fn {k, v} -> {k, cleanup(v, source_id)} end)
[_ | _] ->
data
|> Enum.reject(&match?(%{"source" => ^source_id}, &1))
|> Enum.map(fn v -> cleanup(v, source_id) end)
_ ->
data
end
end
end
Just like the data structure, the code is recursive (for handling list elements and child maps).
The most unique part of this is the middle line in the list case:
@akash-akya@al2o3cr Very cool. I see some similar ideas, will try it out. Thanks you both. I was also thinking about giving Pathex a try, but your solutions are much easier to understand.
@Sebb Unfortunately the data shape is out of my control. It’s an arbitrary external JSON without any standard shape, that represents params that need to be passed to another endpoint.