fix(SerpApi Tool Node): Fix missing query parameter error

[actuallyzefe]

Problem

The SerpAPI tool fails with error Missing query 'q' parameter because it passes the entire n8n input object to the SerpAPI invoke() method instead of extracting the query string

Root Cause

In the execute() method, the code passes the complete input data object (containing json, pairedItem, etc.) directly to tool.invoke(), but SerpAPI expects a simple string parameter for the search query

Summary

Implementation (ToolSerpApi.node.ts)

• Extract query string from input or chatInput fields before invoking the tool
• Pass extracted string directly to tool.invoke() instead of entire object
• Add proper error handling when neither input nor chatInput is provided
• Add logging for missing query string errors

Tests (ToolSerpApi.node.test.ts)

• Update all test cases to use input field matching actual implementation
• Verify tool.invoke() is called with extracted string, not object
• Add test for chatInput fallback when input is not provided
• Add test for error handling when neither field is present
• Verify error logging is called with correct message

Related Linear tickets, Github issues, and Community forum posts

Fixes #21471

Review / Merge checklist

• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with release/backport (if the PR is an urgent fix that needs to be backported)

---

Note

Extracts query from input or chatInput, validates it, and passes the string to SerpAPI; updates tests with fallbacks and error cases.

• ToolSerpApi.node.ts
  • Extract query from json.input or json.chatInput; validate non-empty string and throw NodeOperationError if missing.
  • Pass extracted string to SerpAPI.invoke instead of the whole item.
• ToolSerpApi.node.test.ts
  • Update tests to use input and assert invoke receives the string.
  • Add fallback test for chatInput.
  • Add error tests for missing or invalid query types.

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[CLAassistant]

All committers have signed the CLA.

[n8n-assistant]

Hey @actuallyzefe,

Thank you for your contribution. We appreciate the time and effort you’ve taken to submit this pull request.

Before we can proceed, please ensure the following:
• Tests are included for any new functionality, logic changes or bug fixes.
• The PR aligns with our contribution guidelines.

Regarding new nodes:
We no longer accept new nodes directly into the core codebase. Instead, we encourage contributors to follow our Community Node Submission Guide to publish nodes independently.

If your node integrates with an AI service that you own or represent, please email [email protected] and we will be happy to discuss the best approach.

About review timelines:
This PR has been added to our internal tracker as "GHC-5374". While we plan to review it, we are currently unable to provide an exact timeframe. Our goal is to begin reviews within a month, but this may change depending on team priorities. We will reach out when the review begins.

Thank you again for contributing to n8n.

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[cursor]

Bug: Nullish coalescing misses empty string fallback bug

The nullish coalescing operator (??) only checks for null/undefined, not other falsy values. If item.input is an empty string ("") and item.chatInput contains a valid query, the code will not fall back to chatInput. Instead, queryString will be "" and the subsequent validation will throw an error, even though a valid query exists in chatInput. This should use the logical OR operator (||) instead to properly handle empty strings as missing input.

 

[cubic-dev-ai]

1 issue found across 2 files

Prompt for AI agents (all 1 issues)

Understand the root cause of the following 1 issues and fix them.


<file name="packages/@n8n/nodes-langchain/nodes/tools/ToolSerpApi/ToolSerpApi.node.ts">

<violation number="1" location="packages/@n8n/nodes-langchain/nodes/tools/ToolSerpApi/ToolSerpApi.node.ts:138">
Rule violated: **Prefer Typeguards over Type casting**

Replace the `as string` assertion with an explicit string check so the query is narrowed without violating the Prefer Typeguards over Type casting rule.</violation>
</file>

_{React with 👍 or 👎 to teach cubic. Mention @cubic-dev-ai to give feedback, ask questions, or re-run the review.}

[cubic-dev-ai]

Rule violated: Prefer Typeguards over Type casting

Replace the as string assertion with an explicit string check so the query is narrowed without violating the Prefer Typeguards over Type casting rule.

Prompt for AI agents

Address the following comment on packages/@n8n/nodes-langchain/nodes/tools/ToolSerpApi/ToolSerpApi.node.ts at line 138:

<comment>Replace the `as string` assertion with an explicit string check so the query is narrowed without violating the Prefer Typeguards over Type casting rule.</comment>

<file context>
@@ -133,8 +134,16 @@ export class ToolSerpApi implements INodeType {
-			const query = inputData[itemIndex];
-			const result = await tool.invoke(query);
+			const item = inputData[itemIndex].json;
+			const queryString = (item.input ?? item.chatInput) as string;
+
+			if (!queryString) {
</file context>

✅ Addressed in 4a476e1