example_test.go

// Copyright (c) 2016 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package zap_test

import (
	"os"
	"time"

	"github.com/uber-common/zap"
)

func Example() {
	// Log in JSON, using zap's reflection-free JSON encoder.
	logger := zap.NewJSON(zap.Info, os.Stdout)

	logger.Warn("Log without structured data...")
	logger.Warn(
		"Or use strongly-typed wrappers to add structured context.",
		zap.String("library", "zap"),
		zap.Duration("latency", time.Nanosecond),
	)

	// Avoid re-serializing the same data repeatedly by creating a child logger
	// with some attached context. That context is added to all the child's
	// log output, but doesn't affect the parent.
	child := logger.With(zap.String("user", "jane@test.com"), zap.Int("visits", 42))
	child.Error("Oh no!")
}

func ExampleNest() {
	logger := zap.NewJSON(zap.Info, os.Stdout)
	// We'd like the logging context to be {"outer":{"inner":42}}
	logger.Debug("Nesting context.", zap.Nest("outer",
		zap.Int("inner", 42),
	))
}