Infer ChoiceField type from model field when in ModelSerializer

Fixes part of issue #69

testproj/articles/migrations/0002_article_article_type.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.0.1 on 2018-02-26 18:32
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('articles', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='article',
+            name='article_type',
+            field=models.PositiveSmallIntegerField(choices=[(1, 'first'), (2, 'second'), (3, 'third'), (7, 'seven'), (8, 'eight')], help_text='IntegerField declared on model with choices=(...) and exposed via ModelSerializer', null=True),
+        ),
+    ]

testproj/articles/models.py

@@ -8,5 +8,9 @@ class Article(models.Model):
     date_created = models.DateTimeField(auto_now_add=True)
     date_modified = models.DateTimeField(auto_now=True)
     author = models.ForeignKey('auth.User', related_name='articles', on_delete=models.CASCADE)
+    article_type = models.PositiveSmallIntegerField(
+        help_text="IntegerField declared on model with choices=(...) and exposed via ModelSerializer",
+        choices=((1, "first"), (2, "second"), (3, "third"), (7, "seven"), (8, "eight")), null=True
+    )
 
     cover = models.ImageField(upload_to='article/original/', blank=True)

testproj/articles/serializers.py

@@ -16,7 +16,7 @@ class ArticleSerializer(serializers.ModelSerializer):
     class Meta:
         model = Article
         fields = ('title', 'author', 'body', 'slug', 'date_created', 'date_modified',
-                  'references', 'uuid', 'cover', 'cover_name')
+                  'references', 'uuid', 'cover', 'cover_name', 'article_type')
         read_only_fields = ('date_created', 'date_modified',
                             'references', 'uuid', 'cover_name')
         lookup_field = 'slug'