ExJsonschema.RefResolver behaviour (ExJsonschema v0.2.0)

Behaviour for resolving external $ref URIs in JSON Schemas.

Implement this behaviour to control how external schema references are fetched — via HTTP, database, filesystem, a hardcoded map, etc.

Example

defmodule MyApp.SchemaResolver do
  @behaviour ExJsonschema.RefResolver

  @impl true
  def resolve(uris) do
    resolved =
      Map.new(uris, fn uri ->
        {:ok, body} = fetch_schema(uri)
        {uri, body}
      end)

    {:ok, resolved}
  end

  defp fetch_schema(uri), do: {:ok, ~s({"type": "object"})}
end

{:ok, compiled} = ExJsonschema.compile(schema, ref_resolver: MyApp.SchemaResolver)

Transitive resolution

When a ref_resolver is used, ExJsonschema automatically handles transitive references: if a resolved schema itself contains $refs, the resolver is called again for the new URIs until no unresolved external refs remain.

Summary

Callbacks

resolve(uris)

Resolve a list of external $ref URIs to their JSON Schema strings.

Callbacks

resolve(uris)

@callback resolve(uris :: [String.t()]) ::
  {:ok, %{required(String.t()) => String.t()}} | {:error, term()}

Resolve a list of external $ref URIs to their JSON Schema strings.

Receives a list of URI strings and must return either:

{:ok, %{uri => json_string}} — a map from each URI to its JSON content
{:error, term()} — if resolution fails

The resolver may return schemas for a subset of the requested URIs; any missing URIs will be treated as permissive empty schemas ({}).