feedback

Author: nimarb

langfuse/model.py

@@ -370,8 +370,8 @@ def __eq__(self, other):
 
     def compile_with_placeholders(
         self,
-        variables: Dict[str, str],
         placeholders: Dict[str, List[ChatMessageDict]],
+        variables: Optional[Dict[str, str]] = None,
     ) -> List[ChatMessageDict]:
         """Compile chat prompt by first replacing placeholders, then expanding variables.
 
@@ -382,22 +382,26 @@ def compile_with_placeholders(
         Returns:
             List[ChatMessageDict]: Compiled chat messages
         """
+        if variables is None:
+            variables = {}
+
         messages_with_placeholders_replaced: List[ChatMessageDict] = []
 
         # Subsitute the placeholders for their supplied ChatMessages
         for item in self.prompt:
             if item["type"] == "placeholder" and item["name"] in placeholders:
                 if (
-                    isinstance(placeholders[item["name"]], Iterable)
+                    isinstance(placeholders[item["name"]], List)
                     and len(placeholders[item["name"]]) > 0
                 ):
                     messages_with_placeholders_replaced.extend(
                         placeholders[item["name"]]
                     )
                 else:
-                    raise ValueError(
+                    empty_placeholder_error = (
                         f"The provided placeholder: {item['name']} is empty"
                     )
+                    raise ValueError(empty_placeholder_error)
             elif item["type"] == "message":
                 messages_with_placeholders_replaced.append(
                     ChatMessageDict(
@@ -437,7 +441,7 @@ def get_langchain_prompt(self, **kwargs):
                 self._get_langchain_prompt_string(
                     TemplateParser.compile_template(msg["content"], kwargs)
                     if kwargs
-                    else msg["content"]
+                    else msg["content"],
                 ),
             )
             for msg in self.prompt

tests/test_prompt.py

@@ -110,13 +110,13 @@ def test_create_chat_prompt_with_placeholders():
     second_prompt_client = langfuse.get_prompt(prompt_name, type="chat")
 
     messages = second_prompt_client.compile_with_placeholders(
-        variables={"role": "helpful", "task": "coding"},
         placeholders={
             "history": [
                 {"role": "user", "content": "Example: {{task}}"},
                 {"role": "assistant", "content": "Example response"},
             ],
         },
+        variables={"role": "helpful", "task": "coding"},
     )
 
     # Create a test generation using compiled messages
@@ -205,7 +205,7 @@ def test_get_prompt_with_placeholders():
 
 
 @pytest.mark.parametrize(
-    "variables,placeholders,expected_len,expected_contents",
+    ("variables", "placeholders", "expected_len", "expected_contents"),
     [
         # Variables only, no placeholders
         (
@@ -223,7 +223,24 @@ def test_get_prompt_with_placeholders():
                 "examples": [
                     {"role": "user", "content": "Example question"},
                     {"role": "assistant", "content": "Example answer"},
-                ]
+                ],
+            },
+            4,
+            [
+                "You are a {{role}} assistant",
+                "Example question",
+                "Example answer",
+                "Help me with {{task}}",
+            ],
+        ),
+        # Placeholders only, variables None
+        (
+            None,
+            {
+                "examples": [
+                    {"role": "user", "content": "Example question"},
+                    {"role": "assistant", "content": "Example answer"},
+                ],
             },
             4,
             [
@@ -240,7 +257,7 @@ def test_get_prompt_with_placeholders():
                 "examples": [
                     {"role": "user", "content": "Show me {{task}}"},
                     {"role": "assistant", "content": "Here's {{task}}"},
-                ]
+                ],
             },
             4,
             [
@@ -250,13 +267,14 @@ def test_get_prompt_with_placeholders():
                 "Help me with coding",
             ],
         ),
-        # Empty placeholder array
-        (
-            {"role": "helpful", "task": "coding"},
-            {"examples": []},
-            2,
-            ["You are a helpful assistant", "Help me with coding"],
-        ),
+        # # Empty placeholder array
+        # This is expected to fail! If the user provides a placeholder, it should contain an array
+        # (
+        #     {"role": "helpful", "task": "coding"},
+        #     {"examples": []},
+        #     2,
+        #     ["You are a helpful assistant", "Help me with coding"],
+        # ),
         # Unused placeholders
         (
             {"role": "helpful", "task": "coding"},
@@ -288,7 +306,8 @@ def test_compile_with_placeholders(
     )
 
     result = ChatPromptClient(mock_prompt).compile_with_placeholders(
-        variables, placeholders
+        placeholders,
+        variables,
     )
 
     assert len(result) == expected_len