Keep in mind that Code.string_to_quoted is as unsafe as String.to_atom. A new atom will be created for each key, identifier, etc in your input, so it’s an invitation to denial of service. You can avoid this by using :static_atoms_encoder but never, ever parse user input without taking that into account.

Code.eval_string/3 is not safe, as you have full access to the runtime system, you can read the warning in the documentation.

I’ll try this and get back to you.

Thank you

You’re right. The AST is easy to parse.

I might settle for this approach.

Thanks for pointing this out.

Thanks, @kip

JSON would have been my goto approach.

However, there are two nuances I have to consider:

1. Any of Parent, Child, and GrandChild in the example above can be the root node, and the system’s behavior adjusts accordingly.

2. GrandChild can be of multiple types and the keys for each are different (imagine TypeOne{some_key: "Value",...}, TypeTwo{another_key: "Value"...}…)

If I go with JSON, handling these nuances might mean tagging each sub(object) with {"type": "NodeNameHere", ...}.

For our largely non-technical user base, requiring this tag (along with requiring quotes around each JSON key) will be too verbose.

Atom-keyed Elixir structs feel more succinct and expressive.

# JSON
{
  "type": "Parent",
  "field": "Value",
  "another_field": "Another value",
  "child_list": [
      {
          "type": "Child"
          "child_field": "Child 1 data",
          "grandchildren_list": [
            {
              "type": "TypeOne",
              "field": "Value"
            },
            {
              "type": "TypeTwo",
              "another_field": "Some other value"
            }
        ]
      },
      {
          "type": "Child",
          "child_field": "Child 2 data"
      }
  ]
}

vs

# Struct
%Parent{
  field: "Value",
  another_field: "Another value",
  child_list: [
      %Child{
          child_field: "Child 1 data",
          grandchildren_list: [
            %TypeOne{field: "Value"},
            %TypeTwo{another_field: "Some other value"}
        ]
      },
      %Child{child_field: "Child 2 data"}
  ]
}

If there’s a workaround to reduce this verbosity, I’ll surely want to know 'cause parsing JSON will be an almost zero-stress approach for me.