JSON Array support

[kazegusuri]

zap supports nested JSON Objects with zap.Nest or zap.Marshaler, but does not support JSON Array yet. Current workaround is to use zap.Object and implement MarshalJSON to output JSON Array. How about built-in support for JSON Array like zap.Array?

[akshayjshah]

That's definitely on our radar. For now, you can use zap.Object - as long as you're passing a slice of primitive types, you don't even have to implement MarshalJSON.

The best way I can think of to support JSON arrays (while keeping performance good) is to add specific helpers for each slice type. We'd end up with zap.Ints, zap.Floats, zap.Durations, etc.

Are you interested in working on this feature?

[jcorbin]

@akshayjshah , what do you think of the following approach:

diff --git a/keyvalue.go b/keyvalue.go
index cda24f5..862ebb3 100644
--- a/keyvalue.go
+++ b/keyvalue.go
@@ -38,4 +38,26 @@ type KeyValue interface {
    // allocation-heavy. Consider implementing the LogMarshaler interface instead.
    AddObject(key string, value interface{}) error
    AddString(key, value string)
+   AddArray(key, valueAdder func(Values) error)
+}
+
+// Values is an encoding agnostic interface to add array data to a keyed value
+// within a logging context. Like slices, Values aren't safe for concurrent use
+// (though typical use shouldn't require locks).
+//
+// XXX example
+type Values interface {
+   AddBool(value bool)
+   AddFloat64(value float64)
+   AddInt(value int)
+   AddInt64(value int64)
+   AddUint(value uint)
+   AddUint64(value uint64)
+   AddUintptr(value uintptr)
+   AddMarshaler(marshaler LogMarshaler) error
+   // AddObject uses reflection to serialize arbitrary objects, so it's slow and
+   // allocation-heavy. Consider implementing the LogMarshaler interface instead.
+   AddObject(value interface{}) error
+   AddString(value string)
+   AddArray(valueAdder func(Values) error) // XXX to taste depending on how recursive you're feeling this morning ;-)
 }

[akshayjshah]

This is in-progress on the dev branch: #211

[akshayjshah]

Further support in #258.

[akshayjshah]

Landed on dev.