Merge pull request #98 from MarcSkovMadsen/enhancement/error-handling

Enhancement/error handling

Author: MarcSkovMadsen

pyproject.toml

@@ -92,6 +92,7 @@ pydata = [
     "polars",
     "scikit-learn",
     "seaborn",
+    "yfinance",
 ]
 [tool.ruff]
 exclude = [

src/holoviz_mcp/display_mcp/database.py

@@ -24,6 +24,9 @@
 
 from holoviz_mcp.config import get_config
 from holoviz_mcp.config import logger
+from holoviz_mcp.display_mcp.utils import find_extensions
+from holoviz_mcp.display_mcp.utils import find_requirements
+from holoviz_mcp.display_mcp.utils import validate_code
 
 
 class Snippet(BaseModel):
@@ -435,7 +438,7 @@ def create_visualization(
         description: str = "",
         readme: str = "",
         method: Literal["jupyter", "panel"] = "jupyter",
-    ) -> dict[str, str]:
+    ) -> Snippet:
         """Create a visualization request.
 
         This is the core business logic for creating visualizations,
@@ -456,8 +459,8 @@ def create_visualization(
 
         Returns
         -------
-        dict[str, str]
-            Dictionary with 'id', 'url', and 'created_at' keys
+        Snippet
+            The snippet created for the visualization request.
 
         Raises
         ------
@@ -468,10 +471,6 @@ def create_visualization(
         Exception
             If database operation or other errors occur
         """
-        # Import here to avoid circular dependency
-        from holoviz_mcp.display_mcp.utils import find_extensions
-        from holoviz_mcp.display_mcp.utils import find_requirements
-
         # Validate app is not empty
         if not app:
             raise ValueError("App code is required")
@@ -481,6 +480,8 @@ def create_visualization(
         # Validate syntax
         ast.parse(app)  # Raises SyntaxError if invalid
 
+        validation_result = validate_code(app)
+
         # Infer requirements and extensions
         requirements = find_requirements(app)
         extensions = find_extensions(app) if method == "jupyter" else []
@@ -494,16 +495,14 @@ def create_visualization(
             method=method,
             requirements=requirements,
             extensions=extensions,
-            status="pending",
+            status="success" if not validation_result else "error",
+            error_message=validation_result if validation_result else None,
         )
 
-        self.create_snippet(snippet_obj)
+        snippet_saved = self.create_snippet(snippet_obj)
 
         # Return result
-        return {
-            "id": snippet_obj.id,
-            "created_at": snippet_obj.created_at.isoformat(),
-        }
+        return snippet_saved
 
     @staticmethod
     def _row_to_snippet(row: dict) -> Snippet:

src/holoviz_mcp/display_mcp/endpoints.py

@@ -37,21 +37,27 @@ def post(self):
             method = request_body.get("method", "jupyter")
 
             # Call shared business logic
-            result = db.create_visualization(
+            snippet = db.create_visualization(
                 app=code,
                 name=name,
                 description=description,
                 method=method,
             )
+
             if jupyter_base := os.getenv("JUPYTER_SERVER_PROXY_URL"):
                 port = self.request.host.split(":")[-1]
                 base_url = f"{jupyter_base.rstrip('/')}/{port}"
-                url = f"{base_url}/view?id={result['id']}"
+                url = f"{base_url}/view?id={snippet.id}"
             else:
                 full_url = self.request.full_url()
-                url = full_url.replace("/api/snippet", "/view?id=" + result["id"])
+                url = full_url.replace("/api/snippet", "/view?id=" + snippet.id)
 
-            result["url"] = url
+            result = {
+                "id": snippet.id,
+                "url": url,
+            }
+            if snippet.error_message:
+                result["error_message"] = snippet.error_message
 
             # Return success response
             self.set_status(200)

src/holoviz_mcp/display_mcp/utils.py

@@ -2,6 +2,7 @@
 
 import ast
 import importlib.util
+import traceback
 from typing import Any
 
 # Check for pandas availability once at module level
@@ -144,3 +145,31 @@ def get_relative_view_url(id: str) -> str:
         Relative URL to view the visualization
     """
     return f"./view?id={id}"
+
+
+def validate_code(code: str) -> str:
+    """
+    Validate Python code by attempting to execute it.
+
+    Parameters
+    ----------
+    code : str
+        Python code to validate as a string.
+
+    Returns
+    -------
+    str
+        An empty string if the code is valid, otherwise the traceback of the error.
+    """
+    try:
+        exec(code, {}, {})
+    except Exception as e:
+        # Get the traceback but skip the outermost frame (the exec call itself)
+        if e.__traceback__ is not None:
+            tb = e.__traceback__.tb_next  # Skip the exec() frame
+        else:
+            tb = None
+        traceback_str = "".join(traceback.format_exception(type(e), e, tb))
+        traceback_str = traceback_str.strip()
+        return traceback_str
+    return ""

src/holoviz_mcp/holoviz_mcp/server.py

@@ -433,30 +433,17 @@ async def display(
             description=description,
             method=method,
         )
+        url = response.get("url", "")
 
         # Check for errors in response
-        if "error" in response:
-            error_type = response.get("error", "Unknown")
-            message = response.get("message", "Unknown error")
-
-            if ctx:
-                await ctx.error(f"Code execution failed: {error_type}: {message}")
-
-            # Return detailed error
-            error_msg = f"Error: {error_type}\n\n{message}"
-
-            if "traceback" in response:
-                error_msg += f"\n\nTraceback:\n{response['traceback']}"
+        if error_message := response.get("error_message", None):
+            return f"""
+Visualization created with errors. View [here]({url})
 
-            return error_msg
-
-        # Success - return URL
-        url = response.get("url", "")
-
-        if ctx:
-            await ctx.info(f"Created visualization: {url}")
+{error_message}
+"""
 
-        return f"Visualization created successfully!\n\nView at: {url}"
+        return f"Visualization created successfully!\n\nView [here]({url})"
 
     except Exception as e:
         logger.exception(f"Error creating visualization: {e}")

tests/display_mcp/test_utils.py

@@ -91,3 +91,19 @@ def test_extract_last_expression_syntax_error(self):
 
         with pytest.raises(ValueError, match="Syntax error"):
             extract_last_expression(code)
+
+        def test_validate_code_valid(self):
+            """Test validate_code with valid Python code."""
+            from holoviz_mcp.display_mcp.utils import validate_code
+
+            code = "x = 1\ny = 2\nz = x + y"
+            result = validate_code(code)
+            assert result == ""
+
+        def test_validate_code_invalid(self):
+            """Test validate_code with invalid Python code."""
+            from holoviz_mcp.display_mcp.utils import validate_code
+
+            code = "x = 1\ny = 2\nz = x + undefined_var"
+            result = validate_code(code)
+            assert "NameError" in result