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BitLogger/docs/api/logger-error.md
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2026-05-12 16:06:00 +08:00

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---
name: logger-error
group: api
category: logging
update-time: 20260512
description: Emit an error-level record through the logger using the highest built-in severity shortcut.
key-word:
- logger
- error
- sync
- public
---
## Logger-error
Emit an error-level record through the synchronous logger. This is the convenience wrapper for `log(Level::Error, ...)`.
### Interface
```moonbit
pub fn[S : Sink] Logger::error(self : Logger[S], message : String, fields~ : Array[Field] = []) -> Unit {}
```
#### input
- `self : Logger[S]` - Logger that should emit the error record.
- `message : String` - Error message text.
- `fields : Array[Field]` - Optional structured fields attached to the record.
#### output
- `Unit` - No return value. The record is handled according to the logger threshold and sink pipeline.
### Explanation
Detailed rules explaining key parameters and behaviors
- This helper delegates to `log(Level::Error, ...)`.
- `Error` is the highest built-in severity in this sync logger API.
- Per-call target override is not exposed here; use `log(...)` when explicit target control is required.
- Sink composition, filtering, patching, and queue wrappers still apply normally.
### How to Use
Here are some specific examples provided.
#### When Report A Failing Operation
When an operation should emit a high-severity failure event:
```moonbit
logger.error("worker execution failed")
```
In this example, the call site clearly communicates failure severity.
#### When Attach Structured Error Context
When an error event should include diagnostic fields:
```moonbit
logger.error("dispatch failed", fields=[field("job_id", "42")])
```
In this example, the record carries machine-readable context without dropping to the generic `log(...)` form.
### Error Case
e.g.:
- If the logger minimum level is above `Error`, the call still returns without writing, though this configuration is unusual.
- If a target override is required, use `log(...)` instead of this severity shortcut.
### Notes
1. Use this helper for high-severity application failures.
2. Emitting an error record is separate from throwing or handling program exceptions.