multer
| Property | Value |
|---|---|
| Package | multer |
| Versions Covered | >=2.0.0 <3.0.0 |
| Contract Version | 1.0.0 |
| Status | production |
| Last Verified | 2026-02-26 |
| Maintainer | corpus-team |
Installation
npm install multer
Covered Functions
This contract covers 2 function(s):
single()
Middleware for handling single file upload
Import:
import { single } from 'multer';
Postconditions
What happens after calling this function:
🔴 ERROR - single-throws-multer-error
Condition: file upload fails due to size limit, file type, or disk error
Throws: MulterError
Required Handling:
Caller MUST add error handling middleware after multer to catch MulterError. Check error.code for specific failure reason (LIMIT_FILE_SIZE, LIMIT_UNEXPECTED_FILE, etc.)
📖 Source
Edge Cases
Known gotchas and sharp edges:
⚠️ WARNING - file-size-dos-prevention
Configure limits option to prevent DoS via large file uploads. Unlimited file sizes can exhaust disk space or memory.
📖 Source
⚠️ WARNING - file-filter-validation
Use fileFilter to validate file types and prevent malicious uploads. Without validation, users can upload executables or scripts.
📖 Source
array()
Middleware for handling multiple file uploads
Import:
import { array } from 'multer';
Postconditions
What happens after calling this function:
🔴 ERROR - array-throws-multer-error
Condition: one or more file uploads fail
Throws: MulterError
Required Handling:
Caller MUST add error handling middleware after multer to catch MulterError. Multiple file uploads can fail individually or collectively.
📖 Source
Example: Proper Error Handling
import multer from 'multer';
async function example() {
try {
const result = await single(/* args */);
// Handle success
return result;
} catch (error) {
// Handle error according to contract postconditions
console.error('Error:', error);
throw error;
}
}