[庫地址](https://www.npmjs.com/package/express-winston)

express-winston 為 express.js 應用程式的請求和錯誤記錄提供中介軟體。 它使用“白名單”從請求和（0.2.x 中新增的）響應物件中選擇屬性。

要使用 express-winston，您需要將以下內容新增到您的應用程式中：

在 package.json 中：

```json
{
  "dependencies": {
    "...": "...",
    "winston": "^3.0.0",
    "express-winston": "^4.0.4",
    "...": "..."
  }
}
```

server.js:

```typescript
var winston = require('winston'),
    expressWinston = require('express-winston');
```

# Request Logging

使用 expressWinston.logger(options) 建立一箇中介軟體來記錄您的 HTTP 請求。

```typescript
 var router = require('./my-express-router');

app.use(expressWinston.logger({
      transports: [
        new winston.transports.Console()
      ],
      format: winston.format.combine(
        winston.format.colorize(),
        winston.format.json()
      ),
      meta: true, // optional: control whether you want to log the meta data about the request (default to true)
      msg: "HTTP {{req.method}} {{req.url}}", // optional: customize the default logging message. E.g. "{{res.statusCode}} {{req.method}} {{res.responseTime}}ms {{req.url}}"
      expressFormat: true, // Use the default Express/morgan request formatting. Enabling this will override any msg if true. Will only output colors with colorize set to true
      colorize: false, // Color the text and status code, using the Express/morgan color palette (text: gray, status: default green, 3XX cyan, 4XX yellow, 5XX red).
      ignoreRoute: function (req, res) { return false; } // optional: allows to skip some log messages based on request and/or response
    }));

app.use(router); // notice how the router goes after the logger.
```

引數定義：

> transports: [<winstontransport>], // list of all winston transports instances to use.
    format: [<logform.format>], // formatting desired for log output.
    winstonInstance: <winstonlogger>, // a winston logger instance. If this is provided the transports and formats options are ignored.
    level: String or function(req, res) { return String; }, // log level to use, the default is "info". Assign a  function to dynamically set the level based on request and response, or a string to statically set it always at that level. statusLevels must be false for this setting to be used.
    msg: String or function, // customize the default logging message. E.g. "{{res.statusCode}} {{req.method}} {{res.responseTime}}ms {{req.url}}", "HTTP {{req.method}} {{req.url}}" or function(req, res) { return `${res.statusCode} - ${req.method}`.  Warning: while supported, returning mustache style interpolation from an options.msg function has performance and memory implications under load.
    expressFormat: Boolean, // Use the default Express/morgan request formatting. Enabling this will override any msg if true. Will only output colors when colorize set to true
    colorize: Boolean, // Color the text and status code, using the Express/morgan color palette (text: gray, status: default green, 3XX cyan, 4XX yellow, 5XX red).
    meta: Boolean, // control whether you want to log the meta data about the request (default to true).
    baseMeta: Object, // default meta data to be added to log, this will be merged with the meta data.
    metaField: String, // if defined, the meta data will be added in this field instead of the meta root object. Defaults to 'meta'. Set to `null` to store metadata at the root of the log entry.
    requestField: [String] // the property of the metadata to store the request under (default 'req'). Set to null to exclude request from metadata
    statusLevels: Boolean or Object, // different HTTP status codes caused log messages to be logged at different levels (info/warn/error), the default is false. Use an object to control the levels various status codes are logged at. Using an object for statusLevels overrides any setting of options.level.
    ignoreRoute: function (req, res) { return false; }, // A function to determine if logging is skipped, defaults to returning false. Called _before_ any later middleware.
    skip: function(req, res) { return false; }, // A function to determine if logging is skipped, defaults to returning false. Called _after_ response has already been sent.
    requestFilter: function (req, propName) { return req[propName]; }, // A function to filter/return request values, defaults to returning all values allowed by whitelist. If the function returns undefined, the key/value will not be included in the meta.
    responseFilter: function (res, propName) { return res[propName]; }, // A function to filter/return response values, defaults to returning all values allowed by whitelist. If the function returns undefined, the key/value will not be included in the meta.
    requestWhitelist: [String], // Array of request properties to log. Overrides global requestWhitelist for this instance
    responseWhitelist: [String], // Array of response properties to log. Overrides global responseWhitelist for this instance
    bodyWhitelist: [String], // Array of body properties to log. Overrides global bodyWhitelist for this instance
    bodyBlacklist: [String], // Array of body properties to omit from logs. Overrides global bodyBlacklist for this instance
    ignoredRoutes: [String], // Array of paths to ignore/skip logging. Overrides global ignoredRoutes for this instance
    dynamicMeta: function(req, res) { return [Object]; } // Extract additional meta data from request or response (typically req.user data if using passport). meta must be true for this function to be activated
    headerBlacklist: [String], // Array of headers to omit from logs. Applied after any previous filters.

一個完整的例子：

```typescript
  var express = require('express');
    var expressWinston = require('express-winston');
    var winston = require('winston'); // for transports.Console
    var app = module.exports = express();

app.use(express.bodyParser());
    app.use(express.methodOverride());

// Let's make our express `Router` first.
    var router = express.Router();
    router.get('/error', function(req, res, next) {
      // here we cause an error in the pipeline so we see express-winston in action.
      return next(new Error("This is an error and it should be logged to the console"));
    });

router.get('/', function(req, res, next) {
      res.write('This is a normal request, it should be logged to the console too');
      res.end();
    });

// express-winston logger makes sense BEFORE the router
    app.use(expressWinston.logger({
      transports: [
        new winston.transports.Console()
      ],
      format: winston.format.combine(
        winston.format.colorize(),
        winston.format.json()
      )
    }));

// Now we can tell the app to use our routing code:
    app.use(router);

// express-winston errorLogger makes sense AFTER the router.
    app.use(expressWinston.errorLogger({
      transports: [
        new winston.transports.Console()
      ],
      format: winston.format.combine(
        winston.format.colorize(),
        winston.format.json()
      )
    }));

// Optionally you can include your custom error handler after the logging.
    app.use(express.errorLogger({
      dumpExceptions: true,
      showStack: true
    }));

app.listen(3000, function(){
      console.log("express-winston demo listening on port %d in %s mode", this.address().port, app.settings.env);
    });
```

訪問 /，能看到如下的日誌：

> {
  "req": {
    "httpVersion": "1.1",
    "headers": {
      "host": "localhost:3000",
      "connection": "keep-alive",
      "accept": "*/*",
      "user-agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_4) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.57 Safari/536.11",
      "accept-encoding": "gzip,deflate,sdch",
      "accept-language": "en-US,en;q=0.8,es-419;q=0.6,es;q=0.4",
      "accept-charset": "ISO-8859-1,utf-8;q=0.7,*;q=0.3",
      "cookie": "connect.sid=nGspCCSzH1qxwNTWYAoexI23.seE%2B6Whmcwd"
    },
    "url": "/",
    "method": "GET",
    "originalUrl": "/",
    "query": {}
  },
  "res": {
    "statusCode": 200
  },
  "responseTime" : 12,
  "level": "info",
  "message": "HTTP GET /favicon.ico"
}

控制檯列印的日誌如下：

![](https://img-blog.csdnimg.cn/img_convert/7eb4e8cafae34fd41012c223cdaa3b68.png)</winstonlogger></logform.format></winstontransport>

express-winston 庫的學習筆記

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