fix: handle Message objects in build_output by extracting text attribute

[edwinjosechittilappilly]

Summary by CodeRabbit

• Bug Fixes
  • Improved handling of tool arguments by ensuring that message-type inputs are properly converted to text before processing. This enhances compatibility and prevents errors when using message objects as tool arguments.

[coderabbitai]

Walkthrough

A type check was introduced in the build_output method of the MCPToolsComponent class to handle Message objects. Now, when constructing keyword arguments for tool execution, any Message instance is replaced by its text attribute, ensuring that only the textual content is passed to the tool's coroutine.

Changes

File	Change Summary
src/backend/base/langflow/components/data/mcp_component.py	Added type check in build_output to extract .text from Message instances in tool arguments.

Sequence Diagram(s)

sequenceDiagram
    participant User
    participant MCPToolsComponent
    participant ToolCoroutine

    User->>MCPToolsComponent: Provide tool argument values
    MCPToolsComponent->>MCPToolsComponent: Iterate over argument values
    alt Value is Message
        MCPToolsComponent->>MCPToolsComponent: Extract text attribute
    else Value is not Message
        MCPToolsComponent->>MCPToolsComponent: Use value as is
    end
    MCPToolsComponent->>ToolCoroutine: Call with processed arguments
    ToolCoroutine-->>MCPToolsComponent: Return result
    MCPToolsComponent-->>User: Output result

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📥 Commits

Reviewing files that changed from the base of the PR and between 0d74474 and 4e7b44f.

📒 Files selected for processing (1)

• src/backend/base/langflow/components/data/mcp_component.py (2 hunks)

🧰 Additional context used

📓 Path-based instructions (3)

`src/backend/base/langflow/components/**/*`: Add new backend components to the appropriate subdirectory under src/backend/base/langflow/components/.

src/backend/base/langflow/components/**/*: Add new backend components to the appropriate subdirectory under src/backend/base/langflow/components/.

📄 Source: CodeRabbit Inference Engine (.cursor/rules/backend_development.mdc)

List of files the instruction was applied to:

• src/backend/base/langflow/components/data/mcp_component.py

`src/backend/**/*component*.py`: In your component class, set the 'icon' attribute to a string matching the frontend icon mapping exactly (case-sensitive).

src/backend/**/*component*.py: In your component class, set the 'icon' attribute to a string matching the frontend icon mapping exactly (case-sensitive).

📄 Source: CodeRabbit Inference Engine (.cursor/rules/icons.mdc)

List of files the instruction was applied to:

• src/backend/base/langflow/components/data/mcp_component.py

`src/backend/**/components/**/*.py`: In your component class, set the 'icon' attribute to a string matching the frontend icon mapping exactly (case-sensitive).

src/backend/**/components/**/*.py: In your component class, set the 'icon' attribute to a string matching the frontend icon mapping exactly (case-sensitive).

📄 Source: CodeRabbit Inference Engine (.cursor/rules/icons.mdc)

List of files the instruction was applied to:

• src/backend/base/langflow/components/data/mcp_component.py

⏰ Context from checks skipped due to timeout of 90000ms (2)

• GitHub Check: Update Starter Projects
• GitHub Check: Optimize new Python code in this PR

🔇 Additional comments (2)

src/backend/base/langflow/components/data/mcp_component.py (2)

17-17: LGTM: Import addition supports the new Message type check.

The import of Message from langflow.schema.message is correctly added to support the type checking functionality introduced in the build_output method.

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409-412: Excellent improvement: Message objects are now properly handled.

The type check ensures that when Message objects are passed as tool arguments, only their textual content is extracted and passed to the MCP tool's coroutine. This prevents potential serialization issues and ensures tools receive the expected primitive data types.

The implementation is clean and follows good practices:

• Uses proper isinstance type checking
• Extracts the text attribute from Message objects
• Falls back to the original value for non-Message types
• Maintains backward compatibility

✨ Finishing Touches

• 📝 Generate Docstrings

🧪 Generate Unit Tests

• Create PR with Unit Tests
• Post Copyable Unit Tests in Comment
• Commit Unit Tests in branch fix-mcp-component

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[ogabrielluiz]

LGTM

[edwinjosechittilappilly]

closes #8166