JViewer

JViewer is an excellent way to declaratively represent Elixir data in a JSON encodable format.

Declarative

Explicitly describe what you want your data to look like in a schema.

defmodule MyApp.DataPresenter do
  import JViewer

  @return_schema object(
    fields: [
      field(
        key: "id",
        type: number()
      ),
      field(
        key: "nested_data",
        source_key: "data",
        type: object(
          fields: [
            field(
              key: "data",
              handler: &MyApp.Handlers.data_handler/2
            ),
            ...
          ]
        ),
        ...
      )
    ]
  )
end

Flexible

Add dynamic processing using handlers.

defmodule MyApp.DataPresenter do
  ...

  def present_for_client(data, general_handlers_params) do
    represent(data, @return_schema, general_handlers_params)
  end
end

What should I write here?

Get nicely looking data ready to be encoded in JSON!

%{
  "id" => 1,
  "nested_data" => %{
    ...
  }
}

Installation

The package can be installed by adding j_viewer to your list of dependencies in mix.exs:

def deps do
  [
    {:j_viewer, "~> 0.1.5"}
  ]
end

Documentation

https://hexdocs.pm/j_viewer

P.S.

JViewer's approach and implementation is inspired by an amazing params type validation library Talos.