From 81097520619aef6cd001f85d8bd5ec133a9e20df Mon Sep 17 00:00:00 2001
From: Erick Wilder <erickwilder@gmail.com>
Date: Wed, 17 Feb 2016 10:52:21 +0100
Subject: [PATCH 1/3] Closes #3937. Support callable as the value of `initial`
 for any `serializer.Field`

---
 rest_framework/fields.py |  2 ++
 tests/test_fields.py     | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 6d5962c8e..917e412cc 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -370,6 +370,8 @@ class Field(object):
         Return a value to use when the field is being returned as a primitive
         value, without any object instance.
         """
+        if callable(self.initial):
+            return self.initial()
         return self.initial
 
     def get_value(self, dictionary):
diff --git a/tests/test_fields.py b/tests/test_fields.py
index 43441c2e7..0a878ca79 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -191,6 +191,24 @@ class TestInitial:
         }
 
 
+class TestInitialWithCallable:
+    def setup(self):
+        def initial_value():
+            return 123
+
+        class TestSerializer(serializers.Serializer):
+            initial_field = serializers.IntegerField(initial=initial_value)
+        self.serializer = TestSerializer()
+
+    def test_initial_should_accept_callable(self):
+        """
+        Follows the default ``Field.initial`` behaviour where they accept a
+        callable to produce the initial value"""
+        assert self.serializer.data == {
+            'initial_field': 123,
+        }
+
+
 class TestLabel:
     def setup(self):
         class TestSerializer(serializers.Serializer):

From 908efd665699aedd11878fecaa094c263cf9f457 Mon Sep 17 00:00:00 2001
From: Erick Wilder <erickwilder@gmail.com>
Date: Wed, 17 Feb 2016 11:01:09 +0100
Subject: [PATCH 2/3] #3937 Update docs for the Field.initial attribute.

Add an usage example on how to pass a callable to the `Field.initial` in the docs.
---
 docs/api-guide/fields.md | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/docs/api-guide/fields.md b/docs/api-guide/fields.md
index 5acaf123e..a9bbabc89 100644
--- a/docs/api-guide/fields.md
+++ b/docs/api-guide/fields.md
@@ -81,7 +81,13 @@ A text string that may be used as a description of the field in HTML form fields
 
 ### `initial`
 
-A value that should be used for pre-populating the value of HTML form fields.
+A value that should be used for pre-populating the value of HTML form fields. You may pass a callable to it, just as
+you may do with any regular Django `Field`:
+
+    def user_default_color():
+        return 'blue'
+
+    color = serializers.CharField(initial=user_default_color)
 
 ### `style`
 

From a32baeab0c4324989f0d7f17b934a671f2537105 Mon Sep 17 00:00:00 2001
From: Erick Wilder <erickwilder@gmail.com>
Date: Fri, 19 Feb 2016 09:53:40 +0100
Subject: [PATCH 3/3] Use datetime example for the `Field.initial` attribute

Just like regular Django fields, the example adopted uses a `datetiume.date.today` to
illustrate the functionality.
---
 docs/api-guide/fields.md | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/docs/api-guide/fields.md b/docs/api-guide/fields.md
index a9bbabc89..0409f9a6c 100644
--- a/docs/api-guide/fields.md
+++ b/docs/api-guide/fields.md
@@ -84,10 +84,10 @@ A text string that may be used as a description of the field in HTML form fields
 A value that should be used for pre-populating the value of HTML form fields. You may pass a callable to it, just as
 you may do with any regular Django `Field`:
 
-    def user_default_color():
-        return 'blue'
-
-    color = serializers.CharField(initial=user_default_color)
+    import datetime
+    from rest_framework import serializers
+    class ExampleSerializer(serializers.Serializer):
+        day = serializers.DateField(initial=datetime.date.today)
 
 ### `style`