feature request: Filtering function for maps about jason HOT 1 CLOSED

The main advantage of using the derived implementation is that it pre-computes some things at compile-time. But with dynamic filtering this wouldn't be possible.

One way to do it, is to explicitly implement the protocol with something like:

defimpl Jason.Encode, for: [Struct1, Struct2, ...] do
   def encode(struct, opts) do
      to_encode = for {key, value} <- Map.to_list(stuct), value != nil, key != :__struct__, do: {key, value}
      Jason.Encoder.keyword(to_encode, opts)
   end
end

I believe this should be close to the most efficient implementation possible

from jason.