add Traversal.fetch_in_schema/2 and bang variation

Author: IgnacioGoldchluk

CHANGELOG.md

@@ -4,6 +4,9 @@ All notable changes to this project will be documented in this file.
 
 ## Unreleased
 
+## 0.0.10 [2026-06-17]
+- Rename `Traversal.get_in_schema/2` to `Traversal.fetch_in_schema!/2` and add safe `Traversal.fetch_in_schema/2`
+
 ## 0.0.9 [2026-06-15]
 - Fix regex intersection timeouts by replacing `greenery`/`pythonx` with rustler precompiled `regex_solver`
 

README.md

@@ -14,7 +14,7 @@ Add to your list of dependencies
 ```elixir
 def deps do
   [
-    {:rock_solid, "~> 0.0.9", only: :test}
+    {:rock_solid, "~> 0.0.10", only: :test}
   ]
 end
 ```

lib/rock_solid/context.ex

@@ -91,7 +91,7 @@ defmodule RockSolid.Context do
         path = to_path(relative_pointer)
         reversed_path = Enum.reverse(path)
 
-        non_simplified = get_in_schema(base_schema, path)
+        non_simplified = fetch_in_schema!(base_schema, path)
         simplified = Transformation.simplify(non_simplified, reversed_path)
         put_simplified(pointer, simplified)
         get_ref(pointer)

lib/rock_solid/migration.ex

@@ -457,7 +457,7 @@ defmodule RockSolid.Migration do
     if property?(reversed_path) or definition?(reversed_path) do
       ref_behaviour(schema, reversed_path |> tl() |> Enum.reverse())
     else
-      case get_in_schema(schema, path) do
+      case fetch_in_schema!(schema, path) do
         %{"$schema" => value} -> ref_behaviour(Vocabulary.vocabulary(value))
         _ -> ref_behaviour(schema, remove_last(path))
       end

lib/rock_solid/traversal.ex

@@ -202,36 +202,59 @@ defmodule RockSolid.Traversal do
     end
   end
 
+  @doc """
+  Same as `fetch_in_schema/2` but raises on error
+  """
+  @spec fetch_in_schema!(any(), list(String.t())) :: any()
+  def fetch_in_schema!(schema, path) do
+    case fetch_in_schema(schema, path) do
+      {:ok, value} -> value
+      {:error, exc} when is_exception(exc) -> raise exc
+    end
+  end
+
   @doc """
   Returns the value at the given location in the schema.
 
   The path argument may contain a leading "#". You can convert a JSON Pointer string
   to a valid path by calling `to_path/1`
 
   ## Examples
-      iex> RockSolid.Traversal.get_in_schema(%{"foo" => %{"bar" => "baz"}}, ["#", "foo", "bar"])
-      "baz"
 
-      iex> RockSolid.Traversal.get_in_schema(%{"foo" => ["a", "b"]}, ["#", "foo", "1"])
-      "b"
+      iex> RockSolid.Traversal.fetch_in_schema(%{"foo" => %{"bar" => "baz"}}, ["#", "foo", "bar"])
+      {:ok, "baz"}
+
+      iex> RockSolid.Traversal.fetch_in_schema(%{"foo" => ["a", "b"]}, ["#", "foo", "1"])
+      {:ok, "b"}
+
+      iex> RockSolid.Traversal.fetch_in_schema(%{"foo" => ["a", "b"]}, ["#", "foo", "3"])
+      {:error, %RockSolid.Traversal.InvalidPath{key: "3", schema: ["a", "b"]}}
+
+      iex> RockSolid.Traversal.fetch_in_schema(%{"foo" => 2}, ["#","bar"])
+      {:error, %RockSolid.Traversal.InvalidPath{key: "bar", schema: %{"foo" => 2}}}
   """
-  @spec get_in_schema(any(), list(String.t())) :: any()
-  def get_in_schema(schema, []), do: schema
-  def get_in_schema(schema, ["#" | rest]), do: get_in_schema(schema, rest)
+  @spec fetch_in_schema(any(), list(String.t())) :: {:ok, any()} | {:error, Exception.t()}
+  def fetch_in_schema(schema, []), do: {:ok, schema}
+  def fetch_in_schema(schema, ["#" | rest]), do: fetch_in_schema(schema, rest)
 
-  def get_in_schema(schema, [k | rest]) when is_map(schema) do
+  def fetch_in_schema(schema, [k | rest]) when is_map(schema) do
     key = if Map.has_key?(schema, k), do: k, else: URI.decode(k)
 
     if Map.has_key?(schema, key) do
-      get_in_schema(schema[key], rest)
+      fetch_in_schema(schema[key], rest)
     else
-      # This one should never happen anyway
-      raise InvalidPath, key: key, schema: schema
+      {:error, %InvalidPath{key: key, schema: schema}}
     end
   end
 
-  def get_in_schema(schema, [k | rest]) when is_list(schema),
-    do: get_in_schema(Enum.at(schema, String.to_integer(k)), rest)
+  def fetch_in_schema(schema, [k | rest]) when is_list(schema) do
+    with {index, ""} <- Integer.parse(k),
+         {:ok, element} <- Enum.fetch(schema, index) do
+      fetch_in_schema(element, rest)
+    else
+      _ -> {:error, %InvalidPath{key: k, schema: schema}}
+    end
+  end
 
   @doc """
   Sets a value in the given (existing) path and returns the updated schema

mix.exs

@@ -2,7 +2,7 @@ defmodule RockSolid.MixProject do
   use Mix.Project
 
   @source_url "https://github.com/IgnacioGoldchluk/rock_solid"
-  @version "0.0.9"
+  @version "0.0.10"
 
   def project do
     [

test/rock_solid/traversal_test.exs

@@ -6,13 +6,13 @@ defmodule RockSolid.TraversalTest do
 
   doctest RockSolid.Traversal
 
-  describe "get_in_schema/2" do
+  describe "fetch_in_schema!/2" do
     test "raiss for invalid path" do
       schema = %{"properties" => %{"foo" => %{"type" => "string"}}}
       wrong_path = ["#", "properties", "bar"]
 
       assert_raise Traversal.InvalidPath, ~r/Invalid key 'bar' .*/, fn ->
-        Traversal.get_in_schema(schema, wrong_path)
+        Traversal.fetch_in_schema!(schema, wrong_path)
       end
     end
   end