npm package: @malijs/logger
Description: Development logging middleware for Mali
Author: Bojan D.
Latest version: 0.6.0


# @malijs/logger

[![npm version](https://img.shields.io/npm/v/@malijs/logger.svg?style=flat-square)](https://www.npmjs.com/package/@malijs/logger)
![Tests](https://github.com/malijs/logger/workflows/Tests/badge.svg)

Development style logger middleware for [Mali](https://github.com/malijs/mali).

```sh
--> GetFeature unary
--> GetFeature unary
<-- GetFeature unary 22ms
<-- GetFeature unary 32ms
--> ListFeatures response_stream
<-- ListFeatures response_stream 21ms
--> RecordRoute request_stream
<-- RecordRoute request_stream 10s
--> RouteChat duplex
<-- RouteChat duplex 10ms
```

## Installation

```js
$ npm install @malijs/logger
```

## Example

```js
import logger from '@malijs/logger'
import Mali from 'mali'

const app = new Mali(path.resolve(__dirname, './helloworld.proto'), 'Greeter')
app.use(logger())
app.use({
  sayHello: ({ res, req }) => (res = `Hello ${req.name}`)
})
app.start('0.0.0.0:50051')
```

## API

### logger(options)

#### options.fullName 

To log full name (`fullName`) from context, otherwise logs just the `name`. Default: `false`.

```js
app.use(logger({ fullName: true }))
```

Output:

```sh
--> /routeguide.RouteGuide/GetFeature unary
<-- /routeguide.RouteGuide/GetFeature unary 22ms
```

#### options.timestamp

Enables or disables the inclusion of a timestamp in the log message.
If a function is supplied, it is passed a `Date` timestamp and it must synchronously return the string representation to be logged.
There are predefined timestamp functions: `epochTime` (default), `unixTime`, and `isoTime`.

Default timestamp:

```js
app.use(logger({timestamp: true}))
```

Output:

```
--> 1556325859071 GetFeature unary
<-- 1556325859071 GetFeature unary 6ms
```

With custom predefined timestamp:

```js
app.use(logger({timestamp: logger.isoTime}))
```

Output:

```
--> 2019-04-27T00:44:19.083Z GetFeature unary
<-- 2019-04-27T00:44:19.083Z GetFeature unary 4ms
```

With custom timestamp function:

```js
app.use(logger({ timestamp: date => `${date.toDateString()} ${date.toLocaleTimeString()}` }))
```

Output:

```
--> Fri Apr 26 2019 9:44:19 PM GetFeature unary
<-- Fri Apr 26 2019 9:44:19 PM GetFeature unary 18ms
```

#### Timestamp functions

- `logger.epochTime` - Milliseconds since Unix epoch. Default. Used when `timestamp: true`.
- `logger.unixTime` - Seconds since Unix epoch.
- `logger.isoTime` - Timestamp in ISO time.

#### options.request

Enables or disables the inclusion of request in the log message.
By default `JSON.stringify` is used. If a function is supplied it is passed the request from the context.

```js
app.use(logger({ request: true }))
```

Output:

```
--> GetFeature {"latitude":409146138,"longitude":-746188906} unary
<-- GetFeature unary 2ms
```

#### options.response

Enables or disables the inclusion of response in the log message.
By default `JSON.stringify` is used. If a function is supplied it is passed the response from the context.

```js
app.use(logger({ response: true }))
```

Output:

```
--> GetFeature unary
<-- GetFeature {"location":{"latitude":409146138,"longitude":-746188906},"name":"Berkshire Valley Management Area Trail, Jefferson, NJ, USA"} unary 3ms
```

With custom request and response logging functions:

```js
app.use(logger({ 
  request: req => `(${req.latitude}, ${req.longitude})`,
  response: res => `[${res.name}]`
}))
```

Output:

```
--> GetFeature (409146138, -746188906) unary
<-- GetFeature [Berkshire Valley Management Area Trail, Jefferson, NJ, USA] unary 4ms
```

## Notes

Recommended that you `.use()` this middleware near the top to "wrap" all subsequent middleware.

## License

Apache 2.0