Fix Prompt.get/2 returning nil data and add resolve parameter

CHANGELOG.md

@@ -7,10 +7,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- `Langfuse.Prompt.get/2` now returns prompt data correctly; the underlying HTTP call was sending the prompt name as a query parameter instead of in the URL path
+
 ### Changed
 - Relaxed Elixir version constraint from `~> 1.19` to `~> 1.17` to support projects on Elixir 1.17 and 1.18
 
 ### Added
+- `:resolve` option for `Langfuse.Prompt.get/2`, `Langfuse.Prompt.fetch/2`, `Langfuse.Client.get_prompt/2`, and `Langfuse.HTTP.get_prompt/2` to control server-side prompt dependency resolution
 - GitHub Actions CI with matrix testing across Elixir 1.17/OTP 26, 1.18/OTP 27, and 1.19/OTP 28
 
 ## [0.1.0] - 2025-11-29

devenv.nix

@@ -8,6 +8,7 @@
 
   packages = [
     pkgs.git
+    pkgs.nodejs
   ];
 
   enterShell = ''

lib/langfuse/client.ex

@@ -152,7 +152,11 @@ defmodule Langfuse.Client do
   @spec update_prompt_labels(String.t(), pos_integer(), keyword()) :: response()
   def update_prompt_labels(name, version, opts) do
     body = %{labels: Keyword.fetch!(opts, :labels)}
-    patch("/api/public/v2/prompts/#{URI.encode(name)}/versions/#{version}", body)
+
+    patch(
+      "/api/public/v2/prompts/#{URI.encode(name, &URI.char_unreserved?/1)}/versions/#{version}",
+      body
+    )
   end
 
   @doc """
@@ -167,6 +171,7 @@ defmodule Langfuse.Client do
 
     * `:version` - Specific version number to fetch
     * `:label` - Label to fetch (e.g., "production", "latest")
+    * `:resolve` - Whether to resolve prompt dependencies before returning (defaults to `true` on server)
 
   ## Examples
 
@@ -184,8 +189,9 @@ defmodule Langfuse.Client do
       []
       |> maybe_add_param(:version, opts[:version])
       |> maybe_add_param(:label, opts[:label])
+      |> maybe_add_param(:resolve, opts[:resolve])
 
-    get("/api/public/v2/prompts/#{URI.encode(name)}", params)
+    get("/api/public/v2/prompts/#{URI.encode(name, &URI.char_unreserved?/1)}", params)
   end
 
   @doc """
@@ -199,7 +205,7 @@ defmodule Langfuse.Client do
   """
   @spec get_dataset(String.t()) :: response()
   def get_dataset(name) do
-    get("/api/public/v2/datasets/#{URI.encode(name)}")
+    get("/api/public/v2/datasets/#{URI.encode(name, &URI.char_unreserved?/1)}")
   end
 
   @doc """
@@ -837,7 +843,7 @@ defmodule Langfuse.Client do
   """
   @spec delete_dataset(String.t()) :: :ok | {:error, term()}
   def delete_dataset(name) do
-    delete("/api/public/v2/datasets/#{URI.encode(name)}")
+    delete("/api/public/v2/datasets/#{URI.encode(name, &URI.char_unreserved?/1)}")
   end
 
   @doc """

lib/langfuse/http.ex

@@ -89,17 +89,19 @@ defmodule Langfuse.HTTP do
 
     * `:version` - Specific version number
     * `:label` - Label to fetch (e.g., "production")
+    * `:resolve` - Whether to resolve prompt dependencies before returning (defaults to `true` on server)
 
   """
   @impl true
   @spec get_prompt(String.t(), keyword()) :: response()
   def get_prompt(name, opts \\ []) do
     params =
-      [name: name]
+      []
       |> maybe_add(:version, opts[:version])
       |> maybe_add(:label, opts[:label])
+      |> maybe_add(:resolve, opts[:resolve])
 
-    get(@prompts_path, params)
+    get("#{@prompts_path}/#{URI.encode(name, &URI.char_unreserved?/1)}", params)
   end
 
   @doc """

lib/langfuse/prompt.ex

@@ -84,6 +84,7 @@ defmodule Langfuse.Prompt do
 
     * `:version` - Specific version number to fetch.
     * `:label` - Label to fetch (e.g., "production", "latest").
+    * `:resolve` - Whether to resolve prompt dependencies before returning (defaults to `true` on server).
     * `:cache_ttl` - Cache TTL in milliseconds. Defaults to 60,000 (1 minute).
     * `:fallback` - Fallback prompt struct or template to use if fetch fails.
       Can be a `%Langfuse.Prompt{}` struct or a string template.
@@ -188,6 +189,7 @@ defmodule Langfuse.Prompt do
 
     * `:version` - Specific version number to fetch.
     * `:label` - Label to fetch (e.g., "production", "latest").
+    * `:resolve` - Whether to resolve prompt dependencies before returning (defaults to `true` on server).
 
   ## Examples
 
@@ -324,10 +326,8 @@ defmodule Langfuse.Prompt do
   """
   @spec invalidate(String.t(), keyword()) :: :ok
   def invalidate(name, opts \\ []) do
-    key = cache_key(name, opts)
-
     if opts[:version] || opts[:label] do
-      delete_cache_key(key)
+      delete_cache_entries(name, opts[:version], opts[:label])
     else
       delete_cache_by_name(name)
     end
@@ -361,21 +361,28 @@ defmodule Langfuse.Prompt do
   defp cache_key(name, opts) do
     version = opts[:version]
     label = opts[:label]
-    {name, version, label}
+    resolve = if(opts[:resolve] == false, do: false, else: true)
+    {name, version, label, resolve}
   end
 
-  defp delete_cache_key(key) do
-    :ets.delete(:langfuse_prompt_cache, key)
+  defp delete_cache_entries(name, version, label) do
+    :ets.match_delete(
+      :langfuse_prompt_cache,
+      {{name, cache_match(version), cache_match(label), :_}, :_, :_}
+    )
   rescue
     ArgumentError -> :ok
   end
 
   defp delete_cache_by_name(name) do
-    :ets.match_delete(:langfuse_prompt_cache, {{name, :_, :_}, :_, :_})
+    :ets.match_delete(:langfuse_prompt_cache, {{name, :_, :_, :_}, :_, :_})
   rescue
     ArgumentError -> :ok
   end
 
+  defp cache_match(nil), do: :_
+  defp cache_match(value), do: value
+
   defp get_cached(key) do
     case :ets.lookup(:langfuse_prompt_cache, key) do
       [{^key, prompt, expires_at}] ->

test/langfuse/http_test.exs

@@ -153,9 +153,7 @@ defmodule Langfuse.HTTPTest do
     end
 
     test "get_prompt/2 fetches prompt by name", %{bypass: bypass} do
-      Bypass.expect_once(bypass, "GET", "/api/public/v2/prompts", fn conn ->
-        assert conn.query_string =~ "name=test-prompt"
-
+      Bypass.expect_once(bypass, "GET", "/api/public/v2/prompts/test-prompt", fn conn ->
         conn
         |> Plug.Conn.put_resp_content_type("application/json")
         |> Plug.Conn.resp(
@@ -177,8 +175,7 @@ defmodule Langfuse.HTTPTest do
     end
 
     test "get_prompt/2 with version option", %{bypass: bypass} do
-      Bypass.expect_once(bypass, "GET", "/api/public/v2/prompts", fn conn ->
-        assert conn.query_string =~ "name=test-prompt"
+      Bypass.expect_once(bypass, "GET", "/api/public/v2/prompts/test-prompt", fn conn ->
         assert conn.query_string =~ "version=3"
 
         conn
@@ -194,8 +191,7 @@ defmodule Langfuse.HTTPTest do
     end
 
     test "get_prompt/2 with label option", %{bypass: bypass} do
-      Bypass.expect_once(bypass, "GET", "/api/public/v2/prompts", fn conn ->
-        assert conn.query_string =~ "name=test-prompt"
+      Bypass.expect_once(bypass, "GET", "/api/public/v2/prompts/test-prompt", fn conn ->
         assert conn.query_string =~ "label=staging"
 
         conn
@@ -210,8 +206,24 @@ defmodule Langfuse.HTTPTest do
       assert "staging" in prompt["labels"]
     end
 
+    test "get_prompt/2 with resolve option", %{bypass: bypass} do
+      Bypass.expect_once(bypass, "GET", "/api/public/v2/prompts/test-prompt", fn conn ->
+        assert conn.query_string =~ "resolve=false"
+
+        conn
+        |> Plug.Conn.put_resp_content_type("application/json")
+        |> Plug.Conn.resp(
+          200,
+          Jason.encode!(%{name: "test-prompt", version: 1, prompt: "raw {{dep}}"})
+        )
+      end)
+
+      assert {:ok, prompt} = Langfuse.HTTP.get_prompt("test-prompt", resolve: false)
+      assert prompt["prompt"] == "raw {{dep}}"
+    end
+
     test "get_prompt/2 handles not found", %{bypass: bypass} do
-      Bypass.expect_once(bypass, "GET", "/api/public/v2/prompts", fn conn ->
+      Bypass.expect_once(bypass, "GET", "/api/public/v2/prompts/nonexistent", fn conn ->
         conn
         |> Plug.Conn.put_resp_content_type("application/json")
         |> Plug.Conn.resp(404, Jason.encode!(%{error: "Prompt not found"}))