example to log undefined vals (related to pull #473)

Also, a changelog update for a recent change.
master
Trent Mick 2017-03-04 13:43:38 -08:00
parent 2d535a6395
commit 4d4663758e
2 changed files with 62 additions and 0 deletions

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@ -7,6 +7,8 @@ Known issues:
## not yet released
- [pull #469] Fix a strict mode (`"use strict;"`) error in some versions of
Safari.
## 1.8.8

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@ -0,0 +1,60 @@
#!/usr/bin/env node
/* BEGIN JSSTYLED */
/**
* <https://github.com/trentm/node-bunyan/pull/473> is a change to add a
* feature to Bunyan's log record stringification to log `undefined` values.
* Let's attempt that with a custom raw stream.
*
* Note that a raw stream here isn't ideal, because using a custom raw stream
* means that it is a pain to use some of the other built-in stream types
* (file, rotating-file). However, it might be a satisfactory workaround for
* some.
*
* Example:
* $ node log-undefined-values.js
* {"name":"log-undefined-values","hostname":"danger0.local","pid":28161,"level":30,"anull":null,"aundef":"[Undefined]","anum":42,"astr":"foo","msg":"hi","time":"2017-03-04T20:53:54.331Z","v":0}
* $ node log-undefined-values.js | bunyan
* [2017-03-04T20:54:41.874Z] INFO: log-undefined-values/28194 on danger0.local: hi (anull=null, aundef=[Undefined], anum=42, astr=foo)
*/
/* END JSSTYLED */
var bunyan = require('../lib/bunyan');
var fs = require('fs');
function replacer() {
// Note: If node > 0.10, then could use Set here (see `safeCyclesSet()`
// in bunyan.js) for a performance improvement.
var seen = [];
return function (key, val) {
if (val === undefined) {
return '[Undefined]';
} else if (!val || typeof (val) !== 'object') {
return val;
}
if (seen.indexOf(val) !== -1) {
return '[Circular]';
}
seen.push(val);
return val;
};
}
function LogUndefinedValuesStream(stream) {
this.stream = stream;
}
LogUndefinedValuesStream.prototype.write = function (rec) {
var str = JSON.stringify(rec, replacer()) + '\n';
this.stream.write(str);
}
var log = bunyan.createLogger({
name: 'log-undefined-values',
streams: [ {
level: 'info',
type: 'raw',
stream: new LogUndefinedValuesStream(process.stdout)
} ]
});
log.info({anull: null, aundef: undefined, anum: 42, astr: 'foo'}, 'hi');