diff --git a/wagtail/contrib/wagtailapi/renderers.py b/wagtail/contrib/wagtailapi/renderers.py
index d7f9a5e90..f9828f3a2 100644
--- a/wagtail/contrib/wagtailapi/renderers.py
+++ b/wagtail/contrib/wagtailapi/renderers.py
@@ -6,11 +6,6 @@ from django.utils.six import text_type
 
 from rest_framework import renderers
 
-from taggit.managers import _TaggableManager
-from taggit.models import Tag
-
-from wagtail.wagtailcore.blocks import StreamValue
-
 from .utils import URLPath, ObjectDetailURL, get_base_url
 
 
@@ -35,11 +30,7 @@ class WagtailJSONRenderer(renderers.BaseRenderer):
 
         class WagtailAPIJSONEncoder(DjangoJSONEncoder):
             def default(self, o):
-                if isinstance(o, _TaggableManager):
-                    return list(o.all())
-                elif isinstance(o, Tag):
-                    return o.name
-                elif isinstance(o, URLPath):
+                if isinstance(o, URLPath):
                     return get_full_url(request, o.path)
                 elif isinstance(o, ObjectDetailURL):
                     detail_view = find_model_detail_view(o.model, endpoints)
@@ -48,8 +39,6 @@ class WagtailJSONRenderer(renderers.BaseRenderer):
                         return get_full_url(request, reverse(detail_view, args=(o.pk, )))
                     else:
                         return None
-                elif isinstance(o, StreamValue):
-                    return o.stream_block.get_prep_value(o)
                 else:
                     return super(WagtailAPIJSONEncoder, self).default(o)
 
diff --git a/wagtail/contrib/wagtailapi/serializers.py b/wagtail/contrib/wagtailapi/serializers.py
index a28f6f2f5..c0f26101c 100644
--- a/wagtail/contrib/wagtailapi/serializers.py
+++ b/wagtail/contrib/wagtailapi/serializers.py
@@ -7,65 +7,119 @@ from django.utils.encoding import force_text
 
 from modelcluster.models import get_all_child_relations
 
+from taggit.managers import TaggableManager
+
 from rest_framework.serializers import BaseSerializer
 
 from wagtail.utils.compat import get_related_model
 from wagtail.wagtailcore.models import Page
+from wagtail.wagtailcore import fields as wagtailcore_fields
 
 from .utils import ObjectDetailURL, URLPath, BadRequestError, pages_for_site
 
 
-def get_api_data(obj, fields):
+class Field(object):
+    def __init__(self, field_name):
+        self.field_name = field_name
+
+    def get_attribute(self, instance):
+        return getattr(instance, self.field_name)
+
+    def to_representation(self, value):
+        return value
+
+
+class AttrField(Field):
+    def to_representation(self, value):
+        return force_text(value, strings_only=True)
+
+
+class ChildRelationField(Field):
+    def __init__(self, field_name, fields):
+        self.field_name = field_name
+        self.fields = fields
+
+    def to_representation(self, value):
+        return [
+            dict(get_api_data(child_object, self.fields))
+            for child_object in value.all()
+        ]
+
+
+class RelatedObjectField(Field):
+    def to_representation(self, value):
+        model = type(value)
+
+        return OrderedDict([
+            ('id', value.pk),
+            ('meta', OrderedDict([
+                 ('type', model._meta.app_label + '.' + model.__name__),
+                 ('detail_url', ObjectDetailURL(model, value.pk)),
+            ])),
+        ])
+
+
+class StreamField(Field):
+    def to_representation(self, value):
+        return value.stream_block.get_prep_value(value)
+
+
+class TagsField(Field):
+    def to_representation(self, value):
+        return list(value.all().values_list('name', flat=True))
+
+
+def get_serializer_fields(model, fields):
     # Find any child relations (pages only)
     child_relations = {}
-    if isinstance(obj, Page):
+    if issubclass(model, Page):
         child_relations = {
             child_relation.field.rel.related_name: get_related_model(child_relation)
-            for child_relation in get_all_child_relations(type(obj))
+            for child_relation in get_all_child_relations(model)
         }
 
     # Loop through fields
     for field_name in fields:
         # Check child relations
         if field_name in child_relations and hasattr(child_relations[field_name], 'api_fields'):
-            yield field_name, [
-                dict(get_api_data(child_object, child_relations[field_name].api_fields))
-                for child_object in getattr(obj, field_name).all()
-            ]
+            yield ChildRelationField(field_name, child_relations[field_name].api_fields)
             continue
 
         # Check django fields
         try:
-            field = obj._meta.get_field(field_name)
+            field = model._meta.get_field(field_name)
 
             if field.rel and isinstance(field.rel, models.ManyToOneRel):
-                # Foreign key
-                val = field._get_val_from_obj(obj)
-
-                if val:
-                    yield field_name, OrderedDict([
-                        ('id', field._get_val_from_obj(obj)),
-                        ('meta', OrderedDict([
-                             ('type', field.rel.to._meta.app_label + '.' + field.rel.to.__name__),
-                             ('detail_url', ObjectDetailURL(field.rel.to, val)),
-                        ])),
-                    ])
-                else:
-                    yield field_name, None
+                yield RelatedObjectField(field_name)
+            elif isinstance(field, wagtailcore_fields.StreamField):
+                yield StreamField(field_name)
+            elif isinstance(field, TaggableManager):
+                yield TagsField(field_name)
             else:
-                yield field_name, field._get_val_from_obj(obj)
+                yield AttrField(field_name)
 
             continue
         except models.fields.FieldDoesNotExist:
             pass
 
         # Check attributes
-        if hasattr(obj, field_name):
-            value = getattr(obj, field_name)
-            yield field_name, force_text(value, strings_only=True)
+        if hasattr(model, field_name):
+            yield AttrField(field_name)
             continue
 
 
+def get_api_data(obj, fields):
+    serializer_fields = get_serializer_fields(type(obj), fields)
+
+    for field in serializer_fields:
+        value = field.get_attribute(obj)
+
+        if value is not None:
+            yield field.field_name, field.to_representation(value)
+        else:
+            yield field.field_name, None
+
+
 class WagtailSerializer(BaseSerializer):
     def to_representation(self, instance):
         request = self.context['request']