Adding `BLANK_CHOICE_DASH` as a choice if the model's field isn't required

1 files changed, 3 insertions, 0 deletions

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index c83ee5ec..7fd4c638 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -15,6 +15,7 @@ import warnings
 from django.core import validators
 from django.core.exceptions import ValidationError
 from django.conf import settings
+from django.db.models.fields import BLANK_CHOICE_DASH
 from django import forms
 from django.forms import widgets
 from django.utils.encoding import is_protected_type
@@ -402,6 +403,8 @@ class ChoiceField(WritableField):
     def __init__(self, choices=(), *args, **kwargs):
         super(ChoiceField, self).__init__(*args, **kwargs)
         self.choices = choices
+        if not self.required:
+            self.choices = BLANK_CHOICE_DASH + self.choices
 
     def _get_choices(self):
         return self._choices