From 511792f912917750f1b62629b2060ca36a59f1be Mon Sep 17 00:00:00 2001
From: Shuhao Wu <shuhao@shuhaowu.com>
Date: Mon, 9 Jun 2014 11:31:46 -0400
Subject: [PATCH 1/2] Added support to chain withfields

`WithField` and `WithFields` right now doesn't chain properly. Meaning
that if you do something like:

    localLog := logger.WithField("tag", "value")
    localLog.WithField("v1", "value").Info("message1")
    localLog.Info("message2")

The `v1` will be carried over to `message2`.

With this patch, each WithField/WithFields call are isolated.
---
 entry.go | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/entry.go b/entry.go
index 8cd312e..052697c 100644
--- a/entry.go
+++ b/entry.go
@@ -38,15 +38,23 @@ func (entry *Entry) String() (string, error) {
 }
 
 func (entry *Entry) WithField(key string, value interface{}) *Entry {
-	entry.Data[key] = value
-	return entry
+	data := Fields{}
+	for k, v := range entry.Data {
+		data[k] = v
+	}
+	data[key] = value
+	return &Entry{Logger: entry.Logger, Data: data}
 }
 
 func (entry *Entry) WithFields(fields Fields) *Entry {
-	for key, value := range fields {
-		entry.WithField(key, value)
+	data := Fields{}
+	for k, v := range entry.Data {
+		data[k] = v
 	}
-	return entry
+	for k, v := range fields {
+		data[k] = v
+	}
+	return &Entry{Logger: entry.Logger, Data: data}
 }
 
 func (entry *Entry) log(level string, levelInt Level, msg string) string {

From 7a3a90cb3dace16f6732f12bf05f469e1e921a19 Mon Sep 17 00:00:00 2001
From: Shuhao Wu <shuhao@shuhaowu.com>
Date: Mon, 9 Jun 2014 11:53:23 -0400
Subject: [PATCH 2/2] Added test

---
 entry.go       |  7 +------
 logrus_test.go | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/entry.go b/entry.go
index 052697c..08cc15f 100644
--- a/entry.go
+++ b/entry.go
@@ -38,12 +38,7 @@ func (entry *Entry) String() (string, error) {
 }
 
 func (entry *Entry) WithField(key string, value interface{}) *Entry {
-	data := Fields{}
-	for k, v := range entry.Data {
-		data[k] = v
-	}
-	data[key] = value
-	return &Entry{Logger: entry.Logger, Data: data}
+	return entry.WithFields(Fields{key: value})
 }
 
 func (entry *Entry) WithFields(fields Fields) *Entry {
diff --git a/logrus_test.go b/logrus_test.go
index 96a66a2..82187ae 100644
--- a/logrus_test.go
+++ b/logrus_test.go
@@ -98,3 +98,33 @@ func TestInfoShouldNotAddSpacesBetweenStrings(t *testing.T) {
 		assert.Equal(t, fields["msg"], "testtest")
 	})
 }
+
+func TestWithFieldsShouldAllowAssignments(t *testing.T) {
+	var buffer bytes.Buffer
+	var fields Fields
+
+	logger := New()
+	logger.Out = &buffer
+	logger.Formatter = new(JSONFormatter)
+
+	localLog := logger.WithFields(Fields{
+		"key1": "value1",
+	})
+
+	localLog.WithField("key2", "value2").Info("test")
+	err := json.Unmarshal(buffer.Bytes(), &fields)
+	assert.Nil(t, err)
+
+	assert.Equal(t, "value2", fields["key2"])
+	assert.Equal(t, "value1", fields["key1"])
+
+	buffer = bytes.Buffer{}
+	fields = Fields{}
+	localLog.Info("test")
+	err = json.Unmarshal(buffer.Bytes(), &fields)
+	assert.Nil(t, err)
+
+	_, ok := fields["key2"]
+	assert.Equal(t, false, ok)
+	assert.Equal(t, "value1", fields["key1"])
+}