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BitLogger/docs/api/parse-and-build-application-logger.md
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2026-06-14 01:33:06 +08:00

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---
name: parse-and-build-application-logger
group: api
category: facade
update-time: 20260520
description: Parse JSON logger config text and build the application-facing sync logger alias by delegating directly to the configured runtime logger parse-and-build path.
key-word:
- application
- facade
- parse
- public
---
## Parse-and-build-application-logger
Parse raw JSON config text and build an `ApplicationLogger` in one step. This facade is the application-oriented counterpart to `parse_and_build_logger(...)`.
### Interface
```moonbit
pub fn parse_and_build_application_logger(
input : String,
) -> ApplicationLogger raise ConfigError {
```
#### input
- `input : String` - Raw JSON logger config text.
#### output
- `ApplicationLogger` - Application-facing configured runtime logger built from parsed config.
### Explanation
Detailed rules explaining key parameters and behaviors
- This API delegates to `parse_and_build_logger(...)` directly.
- JSON parsing and config validation happen before the logger is built.
- The parsed config still goes through the normal configured runtime logger build path, including runtime sink selection, optional queue wrapping, and timestamp application.
- Because the result is only the `ApplicationLogger` alias over `ConfiguredLogger`, this parse-and-build path returns the same underlying configured runtime logger value that `parse_and_build_logger(...)` would produce directly, without hiding any queue, drain, flush, or file runtime helper methods.
- Use `parse_and_build_library_logger(...)` instead when the same parsed configured logger result should be wrapped and narrowed for a library boundary.
### How to Use
Here are some specific examples provided.
#### When Need Direct JSON Bootstrapping For Applications
When config is stored as text and should be built immediately:
```moonbit
let logger = parse_and_build_application_logger(
"{\"min_level\":\"warn\",\"target\":\"app\",\"sink\":{\"kind\":\"console\"}}",
)
```
In this example, parsing and runtime construction are combined into one facade call.
And any queue/file/runtime helpers selected by the parsed config remain directly available on the returned alias value.
### Error Case
e.g.:
- If the JSON is malformed, a `ConfigError` is raised.
- If the parsed config is invalid, such as an empty file sink path, a `ConfigError` is raised.
### Notes
1. Use this facade when application code wants a text-to-runtime entry point.
2. Use `build_application_logger(...)` when the config is already typed as `LoggerConfig`.
3. Use `parse_and_build_library_logger(...)` instead when text-driven construction should narrow the public sync logger surface for a library boundary.