fix: Server crashes on startup with cryptic error when a Mongo _SCHEMA field has a non-string type

[dblythy]

Closes #9847

Summary by CodeRabbit

• Bug Fixes
  • Improved schema conversion error handling when a field type is missing or invalid.
  • Error messages now clearly identify the affected class and field, making schema issues easier to diagnose.
  • Added coverage for these cases to ensure the expected Parse error is raised.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

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Plan: Pro

Run ID: 72368639-4ea2-40e8-a87f-9cb8d3acd6ae

📥 Commits

Reviewing files that changed from the base of the PR and between 7e9d53a and 59ab0bb.

📒 Files selected for processing (2)

• spec/MongoSchemaCollectionAdapter.spec.js
• src/Adapters/Storage/Mongo/MongoSchemaCollection.js

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📝 Walkthrough

Walkthrough

This change adds validation to mongoFieldToParseSchemaField in MongoSchemaCollection.js so that non-string field types throw a Parse.Error with INCORRECT_TYPE, including class and field name context, instead of crashing. Corresponding spec tests are added to verify this behavior.

Changes

Mongo Schema Field Type Validation

Layer / File(s)	Summary
Type validation in schema field conversion src/Adapters/Storage/Mongo/MongoSchemaCollection.js	mongoFieldToParseSchemaField now throws Parse.Error(INCORRECT_TYPE) with descriptive className/fieldName when type is not a string; caller now passes fieldName and schema._id into it.
Spec tests for invalid field types spec/MongoSchemaCollectionAdapter.spec.js	Imports parse/node and adds test cases asserting _TESTmongoSchemaToParseSchema throws Parse.Error.INCORRECT_TYPE for null and non-string object field types.

Estimated code review effort: 2 (Simple) | ~10 minutes

Related Issues

• #9847: TypeError: type.startsWith is not a function when starting Parse Server with custom schema data — resolved by adding type validation before calling startsWith.

Suggested Labels: bug, needs review

Suggested Reviewers: dblythy, mtrezza

_{🐰 A silent hop, a broken type, no more a crash upon the night; now Parse throws with words so clear, className and field draw near.}

🚥 Pre-merge checks | ✅ 6 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description is largely incomplete and only references the issue; it is missing the required Issue, Approach, and Tasks sections.	Populate the template with an issue summary, implementation approach, and completed task checklist items.

✅ Passed checks (6 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title uses the required fix: prefix and accurately summarizes the Mongo schema startup crash fix.
Linked Issues check	✅ Passed	The change validates non-string _SCHEMA field types and prevents the startup crash described in #9847.
Out of Scope Changes check	✅ Passed	The changes are limited to the reported Mongo schema fix and matching tests, with no unrelated additions.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Security Check	✅ Passed	Only adds type validation and clearer Parse errors in schema parsing; no new injection, auth, or deserialization risk is introduced.
Engage In Review Feedback	✅ Passed	No substantive review feedback was present—only automated @coderabbitai review requests/responses—so there was nothing to engage before merging.

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src/Adapters/Storage/Mongo/MongoSchemaCollection.js

File contains syntax errors that prevent linting: Line 121: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 163: return types can only be used in TypeScript files; Line 165: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 173: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 186: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 190: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 204: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 208: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 208: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 223: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 223: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 223: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 291: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 291: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.; Line 291: Type annotations are a TypeScript only feature. Convert your file to a TypeScript file or remove the syntax.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.66%. Comparing base (cce91e5) to head (59ab0bb).
⚠️ Report is 1 commits behind head on alpha.

Additional details and impacted files

@@           Coverage Diff           @@
##            alpha   #10532   +/-   ##
=======================================
  Coverage   92.66%   92.66%           
=======================================
  Files         193      193           
  Lines       16981    16983    +2     
  Branches      248      248           
=======================================
+ Hits        15736    15738    +2     
  Misses       1224     1224           
  Partials       21       21           

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[dblythy]

@coderabbitai full review

[coderabbitai]

✅ Action performed

Full review finished.

[dblythy]

@coderabbitai full review

[coderabbitai]

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