fix(mongodb): close client connection on dispose

[greymoth-jp]

The mongodb driver creates a MongoClient on first access but never closes it, so the connection pool stays open after storage.dispose(). The redis, deno-kv and db0 (#693) drivers already close their connection on dispose; this brings mongodb in line.

It keeps a reference to the client and closes it in dispose(). The optional chain covers the case where dispose runs before any connection was opened, and MongoClient.close() is safe to call more than once, so the driver.dispose() then storage.dispose() path in the test harness is fine.

Summary by CodeRabbit

• Bug Fixes
  • Improved database connection cleanup to ensure MongoDB clients are properly closed when no longer needed.
  • Added a cleanup action to the driver so resources are released reliably after use.

[coderabbitai]

📝 Walkthrough

Walkthrough

The MongoDB driver now holds a reference to the created MongoClient in a closure-scoped let variable instead of a block-local const. A dispose() method is added to the returned driver object, calling mongoClient?.close() to release the connection.

Changes

MongoDB Driver Lifecycle

Layer / File(s)	Summary
Client hoisting and dispose() src/drivers/mongodb.ts	mongoClient is declared with let in the driver closure so getMongoCollection() assigns to it instead of a block-local variable; a new dispose() method closes the client via await mongoClient?.close().

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

A rabbit hops in, checks the door is shut tight,
dispose() now called to end the MongoDB night.
No clients left open, no connections astray,
We close what we open — the unstorage way! 🐇✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: closing the MongoDB client during dispose.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/drivers/mongodb.ts`:
- Line 32: Declare the shared mongoClient in mongodb.ts as optional/possibly
undefined instead of a definitely assigned MongoClient, since dispose() may run
before getMongoCollection() initializes it. Update the mongoClient declaration
and keep the optional close call in dispose() aligned with that type so strict
definite-assignment checks pass.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: c2c2b4d0-d0cf-4056-bc4e-2ee8943b7e70

📥 Commits

Reviewing files that changed from the base of the PR and between 2727956 and 8613218.

📒 Files selected for processing (1)

• src/drivers/mongodb.ts

[coderabbitai]

🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

echo "== tsconfig strictness =="
fd -HI '^tsconfig.*\.json$' . -x sh -c '
  echo "--- $1"
  jq "{strict:.compilerOptions.strict, strictNullChecks:.compilerOptions.strictNullChecks}" "$1" 2>/dev/null || cat "$1"
' sh {}

echo
echo "== mongodb driver snippet =="
sed -n '30,40p;117,119p' src/drivers/mongodb.ts

Repository: unjs/unstorage

Length of output: 1542

---

Declare mongoClient as optional. dispose() can run before getMongoCollection() assigns the client, and let mongoClient: MongoClient; can fail strict definite-assignment checks at mongoClient?.close().

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/drivers/mongodb.ts` at line 32, Declare the shared mongoClient in
mongodb.ts as optional/possibly undefined instead of a definitely assigned
MongoClient, since dispose() may run before getMongoCollection() initializes it.
Update the mongoClient declaration and keep the optional close call in dispose()
aligned with that type so strict definite-assignment checks pass.