Proper polygon handling in the API

arkindex/documents/serializers/ml.py

 from rest_framework import serializers
 from arkindex_common.ml_tool import MLToolType
-from arkindex.project.serializer_fields import EnumField, MLToolField
+from arkindex.project.serializer_fields import EnumField, MLToolField, PolygonField
 from arkindex.documents.models import \
     Corpus, Element, Page, Transcription, TranscriptionType, DataSource, Classification
 from arkindex.images.serializers import ZoneSerializer
@@ -72,14 +72,7 @@ class TranscriptionCreateSerializer(serializers.Serializer):
     source = serializers.PrimaryKeyRelatedField(
         queryset=DataSource.objects.filter(type=MLToolType.Recognizer),
     )
-    polygon = serializers.ListField(
-        child=serializers.ListField(
-            child=serializers.IntegerField(),
-            min_length=2,
-            max_length=2
-        ),
-        min_length=3
-    )
+    polygon = PolygonField()
     text = serializers.CharField()
     score = serializers.FloatField(min_value=0, max_value=1)
     type = EnumField(TranscriptionType)
@@ -100,14 +93,7 @@ class TranscriptionBulkSerializer(serializers.Serializer):
     in Bulk (used by serializer below)
     Note: no element !
     """
-    polygon = serializers.ListField(
-        child=serializers.ListField(
-            child=serializers.IntegerField(),
-            min_length=2,
-            max_length=2
-        ),
-        min_length=3
-    )
+    polygon = PolygonField()
     text = serializers.CharField()
     score = serializers.FloatField(min_value=0, max_value=1)
     type = EnumField(TranscriptionType)

arkindex/images/serializers.py

 from rest_framework import serializers
+from arkindex.project.serializer_fields import PolygonField
 from arkindex.images.models import Image, Zone
 
 
 class ZoneSerializer(serializers.ModelSerializer):
-    x = serializers.IntegerField(source='polygon.x')
-    y = serializers.IntegerField(source='polygon.y')
-    width = serializers.IntegerField(source='polygon.width')
-    height = serializers.IntegerField(source='polygon.height')
+    polygon = PolygonField()
     image_url = serializers.URLField(source='image.url')
 
     class Meta:
         model = Zone
         fields = (
             'id',
-            'x',
-            'y',
-            'width',
-            'height',
+            'polygon',
             'url',
             'image_url',
         )

arkindex/project/polygon.py

@@ -44,7 +44,7 @@ class Polygon(collections.abc.MutableSequence):
     A hashable Polygon in-memory
     '''
     def __init__(self, points):
-        assert len(points) > 0
+        assert len(points) > 1
         if not all(isinstance(point, Point) for point in points):
             points = [Point(*p) for p in points]
 
@@ -60,11 +60,16 @@ class Polygon(collections.abc.MutableSequence):
         * from a direct polygon as list of tuples
         * from x,y + width,height
         '''
+        if isinstance(data, list):
+            return Polygon(data)
         assert isinstance(data, dict)
 
         # Direct usage
-        if 'polygon' in data and isinstance(data['polygon'], list):
-            return Polygon(data['polygon'])
+        if 'polygon' in data:
+            if isinstance(data['polygon'], list):
+                return Polygon(data['polygon'])
+            elif isinstance(data['polygon'], Polygon):
+                return data['polygon']
 
         # Build from coords
         for k in ('x', 'y', 'width', 'height'):

arkindex/project/serializer_fields.py

@@ -2,6 +2,7 @@ from django.conf import settings
 from rest_framework import serializers
 from enum import Enum
 from arkindex_common.ml_tool import MLTool, MLToolType
+from arkindex.project.polygon import Point, Polygon
 from arkindex.project.tools import elasticsearch_escape
 
 
@@ -50,3 +51,29 @@ class SearchTermsField(serializers.CharField):
     """
     def to_internal_value(self, query_terms):
         return elasticsearch_escape(query_terms)
+
+
+class PointField(serializers.ListField):
+    child = serializers.IntegerField()
+    min_length = 2
+    max_length = 2
+
+    def to_representation(self, point):
+        return [point.x, point.y]
+
+    def to_internal_value(self, coords):
+        try:
+            return Point(*super().to_internal_value(coords))
+        except (AssertionError, TypeError, ValueError) as e:
+            raise serializers.ValidationError(str(e))
+
+
+class PolygonField(serializers.ListField):
+    child = PointField()
+    min_length = 3
+
+    def to_internal_value(self, data):
+        try:
+            return Polygon(super().to_internal_value(data))
+        except (AssertionError, ValueError) as e:
+            raise serializers.ValidationError(str(e))

arkindex/project/tests/test_drf_polygonfield.py

+from unittest import TestCase
+from arkindex.project.polygon import Point, Polygon
+from arkindex.project.serializer_fields import PointField, PolygonField
+from rest_framework.serializers import ValidationError
+
+
+class TestPolygonSerializerField(TestCase):
+
+    def test_pointfield_to_json(self):
+        self.assertListEqual(
+            PointField().to_representation(Point(13, 37)),
+            [13, 37],
+        )
+
+    def test_json_to_pointfield(self):
+        self.assertEqual(
+            PointField().to_internal_value([13, 37]),
+            Point(13, 37),
+        )
+
+    def test_bad_json_to_pointfield(self):
+        with self.assertRaises(ValidationError):
+            PointField().to_internal_value([])
+        with self.assertRaises(ValidationError):
+            PointField().to_internal_value([1, 2, 3])
+        with self.assertRaises(ValidationError):
+            PointField().to_internal_value(['a', 5])
+
+    def test_polygonfield_to_json(self):
+        self.assertListEqual(
+            PolygonField().to_representation(Polygon([
+                Point(10, 20),
+                Point(30, 40),
+                Point(-40, 50),
+            ])),
+            [
+                [10, 20],
+                [30, 40],
+                [-40, 50],
+                [10, 20],
+            ]
+        )
+
+    def test_json_to_polygonfield(self):
+        self.assertEqual(
+            PolygonField().to_internal_value([
+                [10, 20],
+                [30, 40],
+                [-40, 50],
+            ]), Polygon([
+                Point(10, 20),
+                Point(30, 40),
+                Point(-40, 50),
+                Point(10, 20),
+            ])
+        )
+
+    def test_bad_json_to_polygonfield(self):
+        with self.assertRaises(ValidationError):
+            PolygonField().to_internal_value([])
+        with self.assertRaises(ValidationError):
+            PolygonField().to_internal_value([1, 2, 3])
+        with self.assertRaises(ValidationError):
+            PolygonField().to_internal_value([[1, 2]])