LogLayer

Error Handling ​

LogLayer provides robust error handling capabilities with flexible configuration options for how errors are logged and serialized.

Basic Error Logging ​

With a Message ​

The most common way to log an error is using the withError method along with a message:

typescript
const error = new Error('Database connection failed')
log.withError(error).error('Failed to process request')

You can use any log level with error logging:

typescript
// Log error with warning level
log.withError(error).warn('Database connection unstable')

// Log error with info level
log.withError(error).info('Retrying connection')

Error-Only Logging ​

When you just want to log an error without an additional message:

typescript
// Default log level is 'error'
log.errorOnly(new Error('Database connection failed'))

// With custom log level
log.errorOnly(new Error('Connection timeout'), { 
  logLevel: LogLevel.warn 
})

Error Configuration ​

Error Field Name ​

By default, errors are logged under the err field. You can customize this:

typescript
const log = new LogLayer({
  errorFieldName: 'error', // Default is 'err'
})

log.errorOnly(new Error('test'))
// Output: { "error": { "message": "test", "stack": "..." } }

Error Serialization ​

Some logging libraries don't handle Error objects well. You can provide a custom error serializer:

typescript
const log = new LogLayer({
  errorSerializer: (err) => ({
    message: err.message,
    stack: err.stack,
    code: err.code
  }),
})

For libraries like roarr that require error serialization, you can use a package like serialize-error:

typescript
import { serializeError } from 'serialize-error'

const log = new LogLayer({
  errorSerializer: serializeError,
  transport: new RoarrTransport({
    logger: roarr
  })
})

Error Message Copying ​

You can configure LogLayer to automatically copy the error's message as the log message:

typescript
const log = new LogLayer({
  copyMsgOnOnlyError: true,
})

// Will include error.message as the log message
log.errorOnly(new Error('Connection failed'))

You can override this behavior per call:

typescript
// Disable message copying for this call
log.errorOnly(new Error('test'), { copyMsg: false })

// Enable message copying for this call even if disabled globally
log.errorOnly(new Error('test'), { copyMsg: true })

Error in Metadata ​

You can configure errors to be included in the metadata field instead of at the root level:

typescript
const log = new LogLayer({
  errorFieldInMetadata: true,
  metadataFieldName: 'metadata',
})

log.errorOnly(new Error('test'))
// Output: { "metadata": { "err": { "message": "test", "stack": "..." } } }

Combining Errors with Other Data ​

With Metadata ​

You can combine errors with metadata:

typescript
log.withError(new Error('Query failed'))
   .withMetadata({
     query: 'SELECT * FROM users',
     duration: 1500
   })
   .error('Database error')

With Context ​

Errors can be combined with context data:

typescript
log.withContext({ requestId: '123' })
   .withError(new Error('Not found'))
   .error('Resource not found')