Support new nestedKey config to avoid property name collisions with pino standard properties when logging objects

docs/api.md

@@ -201,6 +201,32 @@ Default: `'msg'`
 
 The string key for the 'message' in the JSON object.
 
+<a id=opt-nestedkey></a>
+#### `nestedKey` (String)
+
+Default: `null`
+
+If there's a chance that objects being logged have properties that conflict with those from pino itself (`level`, `timestamp`, `v`, `pid`, etc)
+and duplicate keys in your log records are undesirable, pino can be configured with a `nestedKey` option that causes any `object`s that are logged
+to be placed under a key whose name is the value of `nestedKey`.
+
+This way, when searching something like Kibana for values, one can consistently search under the configured `nestedKey` value instead of the root log record keys.
+
+For example,
+```js
+const logger = require('pino')({
+  nestedKey: 'payload'
+})
+
+const thing = { level: 'hi', time: 'never', foo: 'bar'} // has pino-conflicting properties!
+logger.info(thing)
+
+// logs the following:
+// {"level":30,"time":1578357790020,"pid":91736,"hostname":"x","payload":{"level":"hi","time":"never","foo":"bar"},"v":1}
+```
+In this way, logged objects' properties don't conflict with pino's standard logging properties,
+and searching for logged objects can start from a consistent path.
+
 <a id=prettyPrint></a>
 #### `prettyPrint` (Boolean | Object)
 

lib/symbols.js

@@ -24,6 +24,7 @@ const stringifiersSym = Symbol('pino.stringifiers')
 const endSym = Symbol('pino.end')
 const formatOptsSym = Symbol('pino.formatOpts')
 const messageKeySym = Symbol('pino.messageKey')
+const nestedKeySym = Symbol('pino.nestedKey')
 
 const wildcardFirstSym = Symbol('pino.wildcardFirst')
 
@@ -54,6 +55,7 @@ module.exports = {
   endSym,
   formatOptsSym,
   messageKeySym,
+  nestedKeySym,
   wildcardFirstSym,
   changeLevelNameSym,
   wildcardGsym,

lib/tools.js

@@ -20,7 +20,8 @@ const {
   needsMetadataGsym,
   wildcardGsym,
   redactFmtSym,
-  streamSym
+  streamSym,
+  nestedKeySym
 } = require('./symbols')
 
 function noop () {}
@@ -33,6 +34,7 @@ function genLog (z) {
       } else if (typeof o.setHeader === 'function') {
         o = mapHttpResponse(o)
       }
+      if (this[nestedKeySym]) o = { [this[nestedKeySym]]: o }
       this[writeSym](o, format(null, n, this[formatOptsSym]), z)
     } else this[writeSym](null, format(o, n, this[formatOptsSym]), z)
   }

pino.js

@@ -27,6 +27,7 @@ const {
   endSym,
   formatOptsSym,
   messageKeySym,
+  nestedKeySym,
   useLevelLabelsSym,
   changeLevelNameSym,
   mixinSym,
@@ -40,6 +41,7 @@ const defaultOptions = {
   level: 'info',
   useLevelLabels: false,
   messageKey: 'msg',
+  nestedKey: null,
   enabled: true,
   prettyPrint: false,
   base: { pid, hostname },
@@ -66,6 +68,7 @@ function pino (...args) {
     serializers,
     timestamp,
     messageKey,
+    nestedKey,
     base,
     name,
     level,
@@ -112,6 +115,7 @@ function pino (...args) {
     [endSym]: end,
     [formatOptsSym]: formatOpts,
     [messageKeySym]: messageKey,
+    [nestedKeySym]: nestedKey,
     [serializersSym]: serializers,
     [mixinSym]: mixin,
     [chindingsSym]: chindings

test/basic.test.js

@@ -286,6 +286,26 @@ test('set the messageKey', async ({ is, same }) => {
   })
 })
 
+test('set the nestedKey', async ({ is, same }) => {
+  const stream = sink()
+  const object = { hello: 'world' }
+  const nestedKey = 'stuff'
+  const instance = pino({
+    nestedKey
+  }, stream)
+  instance.info(object)
+  const result = await once(stream, 'data')
+  is(new Date(result.time) <= new Date(), true, 'time is greater than Date.now()')
+  delete result.time
+  same(result, {
+    pid: pid,
+    hostname: hostname,
+    level: 30,
+    stuff: object,
+    v: 1
+  })
+})
+
 test('set undefined properties', async ({ is, same }) => {
   const stream = sink()
   const instance = pino(stream)