Added support for numeric Feature.Id values (Issue #35)

Signed-off-by: Dmitry Kandiner <dmitry.kandiner@gmail.com>

Author: Dmitry Kandiner

src/GeoJSON.Text.Test.Unit/Feature/FeatureCollectionTests.cs

@@ -134,7 +134,7 @@ public void FeatureCollection_Test_IndexOf()
             var actualId = actualFeature.Id;
             var actualIndex = model.Features.IndexOf(actualFeature);
 
-            var expectedId = expectedIds[i];
+            FeatureId expectedId = expectedIds[i];
             var expectedIndex = expectedIndexes[i];
 
             Assert.AreEqual(expectedId, actualId);

src/GeoJSON.Text.Test.Unit/Feature/FeatureTests.cs

@@ -1,3 +1,4 @@
+using GeoJSON.Text.Feature;
 using GeoJSON.Text.Geometry;
 using NUnit.Framework;
 using System;
@@ -24,7 +25,26 @@ public void Can_Deserialize_Point_Feature()
             Assert.IsTrue(feature.Properties.ContainsKey("name"));
             Assert.AreEqual(feature.Properties["name"].ToString(), "Dinagat Islands");
 
-            Assert.AreEqual("test-id", feature.Id);
+            Assert.AreEqual((FeatureId)"test-id", feature.Id);
+
+            Assert.AreEqual(GeoJSONObjectType.Point, feature.Geometry.Type);
+        }
+
+        [Test]
+        public void Can_Deserialize_Point_Feature_With_Numeric_Id()
+        {
+            var json = GetExpectedJson();
+
+            var feature = JsonSerializer.Deserialize<Text.Feature.Feature>(json);
+
+            Assert.IsNotNull(feature);
+            Assert.IsNotNull(feature.Properties);
+            Assert.IsTrue(feature.Properties.Any());
+
+            Assert.IsTrue(feature.Properties.ContainsKey("name"));
+            Assert.AreEqual(feature.Properties["name"].ToString(), "Dinagat Islands");
+
+            Assert.AreEqual((FeatureId)17, feature.Id);
 
             Assert.AreEqual(GeoJSONObjectType.Point, feature.Geometry.Type);
         }
@@ -354,6 +374,32 @@ public void Serialized_And_Deserialized_Feature_Equals_And_Share_HashCode()
             Assert_Are_Equal(left, right); // assert id's + properties doesn't influence comparison and hashcode
         }
 
+        [Test]
+        public void Serialized_And_Deserialized_Feature_With_Numeric_Id_Equals_And_Share_HashCode()
+        {
+            var geometry = GetGeometry();
+
+            var leftFeature = new Text.Feature.Feature(geometry, null, 42);
+            var leftJson = JsonSerializer.Serialize(leftFeature);
+            var left = JsonSerializer.Deserialize<Text.Feature.Feature>(leftJson);
+
+            var rightFeature = new Text.Feature.Feature(geometry, null, 42);
+            var rightJson = JsonSerializer.Serialize(rightFeature);
+            var right = JsonSerializer.Deserialize<Text.Feature.Feature>(rightJson);
+
+            Assert_Are_Equal(left, right); // assert id's doesn't influence comparison and hashcode
+
+            leftFeature = new Text.Feature.Feature(geometry, GetPropertiesInRandomOrder(), uint.MaxValue);
+            leftJson = JsonSerializer.Serialize(leftFeature);
+            left = JsonSerializer.Deserialize<Text.Feature.Feature>(leftJson);
+
+            rightFeature = new Text.Feature.Feature(geometry, GetPropertiesInRandomOrder(), uint.MaxValue);
+            rightJson = JsonSerializer.Serialize(rightFeature);
+            right = JsonSerializer.Deserialize<Text.Feature.Feature>(rightJson);
+
+            Assert_Are_Equal(left, right); // assert id's + properties doesn't influence comparison and hashcode
+        }
+
         [Test]
         public void Feature_Equals_Null_Issue94()
         {

src/GeoJSON.Text.Test.Unit/Feature/FeatureTests_Can_Deserialize_Point_Feature_With_Numeric_Id.json

@@ -0,0 +1,11 @@
+{
+  "type": "Feature",
+  "id" : 17,
+  "geometry": {
+    "type": "Point",
+    "coordinates": [125.6, 10.1]
+  },
+  "properties": {
+    "name": "Dinagat Islands"
+  }
+}

src/GeoJSON.Text.Test.Unit/Feature/GenericFeatureTests.cs

@@ -26,7 +26,7 @@ public void Can_Deserialize_Point_Feature()
             string name = feature.Properties["name"].ToString();
             Assert.AreEqual("Dinagat Islands", name);
 
-            Assert.AreEqual("test-id", feature.Id);
+            Assert.AreEqual((FeatureId)"test-id", feature.Id);
 
             Assert.AreEqual(GeoJSONObjectType.Point, feature.Geometry.Type);
             Assert.AreEqual(125.6, feature.Geometry.Coordinates.Longitude);
@@ -47,7 +47,7 @@ public void Can_Deserialize_LineString_Feature()
             Assert.IsTrue(feature.Properties.ContainsKey("name"));
             Assert.AreEqual("Dinagat Islands", feature.Properties["name"].ToString());
 
-            Assert.AreEqual("test-id", feature.Id);
+            Assert.AreEqual((FeatureId)"test-id", feature.Id);
 
             Assert.AreEqual(GeoJSONObjectType.LineString, feature.Geometry.Type);
 
@@ -103,7 +103,7 @@ public void Can_Deserialize_Typed_Point_Feature()
             Assert.AreEqual(feature.Properties.Name, "Dinagat Islands");
             Assert.AreEqual(feature.Properties.Value, 4.2);
 
-            Assert.AreEqual(feature.Id, "test-id");
+            Assert.AreEqual(feature.Id, (FeatureId)"test-id");
 
             Assert.AreEqual(feature.Geometry.Type, GeoJSONObjectType.Point);
         }

src/GeoJSON.Text.Test.Unit/GeoJSON.Text.Test.Unit.csproj

@@ -39,6 +39,7 @@
   <ItemGroup>
     <EmbeddedResource Include="Feature\FeatureCollectionTests_Can_Deserialize.json" />
     <EmbeddedResource Include="Feature\FeatureCollectionTests_Can_DeserializeGeneric.json" />
+    <EmbeddedResource Include="Feature\FeatureTests_Can_Deserialize_Point_Feature_With_Numeric_Id.json" />
     <EmbeddedResource Include="Feature\FeatureTests_Can_Deserialize_Point_Feature.json" />
     <EmbeddedResource Include="Feature\FeatureTests_Can_Serialize_Dictionary_Subclass.json" />
     <EmbeddedResource Include="Feature\FeatureTests_Can_Serialize_LineString_Feature.json" />

src/GeoJSON.Text/Converters/FeatureIdConverter.cs

@@ -0,0 +1,25 @@
+// Copyright © Joerg Battermann 2014, Matt Hunt 2017
+
+using GeoJSON.Text.Feature;
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace GeoJSON.Text.Converters
+{
+    internal class FeatureIdConverter : JsonConverter<FeatureId>
+    {
+        public override FeatureId Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) => reader.TokenType switch
+        {
+            JsonTokenType.String => reader.GetString(),
+            JsonTokenType.Number => reader.TryGetUInt64(out var value) ? value : throw new JsonException(),
+            _ => throw new JsonException(),
+        };
+
+        public override void Write(Utf8JsonWriter writer, FeatureId value, JsonSerializerOptions options)
+        {
+            if (value.IsNumeric) writer.WriteNumberValue(value);
+            else                 writer.WriteStringValue(value);
+        }
+    }
+}

src/GeoJSON.Text/Feature/Feature.cs

@@ -21,7 +21,7 @@ namespace GeoJSON.Text.Feature
     public class Feature<TGeometry, TProps> : GeoJSONObject, IEquatable<Feature<TGeometry, TProps>>
         where TGeometry : IGeometryObject
     {
-        private string _id;
+        private FeatureId _id;
         private bool _idHasValue = false;
         private TGeometry _geometry;
         private bool _geometryHasValue = false;
@@ -33,14 +33,14 @@ public Feature()
 
         }
 
-        public Feature(TGeometry geometry, TProps properties, string id = null)
+        public Feature(TGeometry geometry, TProps properties, FeatureId id = null)
         {
             Geometry = geometry;
             Properties = properties;
             Id = id;
         }
 
-        public Feature(IGeometryObject geometry, TProps properties, string id = null)
+        public Feature(IGeometryObject geometry, TProps properties, FeatureId id = null)
         {
             Geometry = (TGeometry)geometry;
             Properties = properties;
@@ -53,7 +53,8 @@ public Feature(IGeometryObject geometry, TProps properties, string id = null)
 
         [JsonPropertyName( "id")]
         [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
-        public string Id { 
+        [JsonConverter(typeof(FeatureIdConverter))]
+        public FeatureId Id { 
             get
             {
                 return _id;
@@ -195,12 +196,12 @@ public Feature()
 
         }
 
-        public Feature(IGeometryObject geometry, IDictionary<string, object> properties = null, string id = null)
+        public Feature(IGeometryObject geometry, IDictionary<string, object> properties = null, FeatureId id = null)
             : base(geometry, properties, id)
         {
         }
 
-        public Feature(IGeometryObject geometry, object properties, string id = null)
+        public Feature(IGeometryObject geometry, object properties, FeatureId id = null)
             : base(geometry, properties, id)
         {
         }
@@ -225,7 +226,7 @@ public Feature()
         /// <param name="geometry">The Geometry Object.</param>
         /// <param name="properties">The properties.</param>
         /// <param name="id">The (optional) identifier.</param>
-        public Feature(TGeometry geometry, IDictionary<string, object> properties = null, string id = null)
+        public Feature(TGeometry geometry, IDictionary<string, object> properties = null, FeatureId id = null)
         : base(geometry, properties ?? new Dictionary<string, object>(), id)
         {
         }
@@ -236,7 +237,7 @@ public Feature(TGeometry geometry, IDictionary<string, object> properties = null
         /// <param name="geometry">The Geometry Object.</param>
         /// <param name="properties">The properties.</param>
         /// <param name="id">The (optional) identifier.</param>
-        public Feature(IGeometryObject geometry, IDictionary<string, object> properties = null, string id = null)
+        public Feature(IGeometryObject geometry, IDictionary<string, object> properties = null, FeatureId id = null)
         : base((TGeometry)geometry, properties ?? new Dictionary<string, object>(), id)
         {
         }
@@ -250,7 +251,7 @@ public Feature(IGeometryObject geometry, IDictionary<string, object> properties
         /// properties
         /// </param>
         /// <param name="id">The (optional) identifier.</param>
-        public Feature(TGeometry geometry, object properties, string id = null)
+        public Feature(TGeometry geometry, object properties, FeatureId id = null)
         : this(geometry, GetDictionaryOfPublicProperties(properties), id)
         {
         }
@@ -312,5 +313,32 @@ public override int GetHashCode()
         {
             return !(left?.Equals(right) ?? right is null);
         }
+    }
+
+    public sealed class FeatureId : IEquatable<FeatureId>
+    {
+        private readonly string _strId;
+        private readonly ulong? _numId;
+
+        private FeatureId(string str, ulong? num) => (_strId, _numId) = (str, num);
+
+        public static implicit operator FeatureId(string str) => new(str, null);
+        public static implicit operator FeatureId(ulong num) => new(null, num);
+
+        public bool IsNumeric => _numId.HasValue;
+        public bool IsString => !IsNumeric;
+
+        public static implicit operator string(FeatureId id) => id.IsString ? id._strId : throw new InvalidCastException();
+        public static implicit operator ulong(FeatureId id) => id.IsNumeric ? id._numId.Value : throw new InvalidCastException();
+
+        public override int GetHashCode() => (_strId.GetHashCode() * 397) ^ _numId.GetHashCode();
+
+        public bool Equals(FeatureId other) => _strId == other._strId && _numId == other._numId;
+
+        public override bool Equals(object obj) => obj is FeatureId id && Equals(id);
+
+        public static bool operator ==(FeatureId left, FeatureId right) => left.Equals(right);
+
+        public static bool operator !=(FeatureId left, FeatureId right) => !(left == right);
     }
 }