Added support for button properties.

Src/Notion.Client/Models/Database/Properties/ButtonProperty.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Newtonsoft.Json;
+using System.Threading.Tasks;
+
+namespace Notion.Client
+{
+    public class ButtonProperty : Property
+    {
+        public override PropertyType Type => PropertyType.Button;
+
+        [JsonProperty("button")]
+        public Dictionary<string,object> Button { get; set; }
+    }
+}

Src/Notion.Client/Models/Database/Properties/Property.cs

@@ -26,6 +26,7 @@ namespace Notion.Client
     [JsonSubtypes.KnownSubTypeAttribute(typeof(TitleProperty), PropertyType.Title)]
     [JsonSubtypes.KnownSubTypeAttribute(typeof(UrlProperty), PropertyType.Url)]
     [JsonSubtypes.KnownSubTypeAttribute(typeof(UniqueIdProperty), PropertyType.UniqueId)]
+    [JsonSubtypes.KnownSubTypeAttribute(typeof(ButtonProperty), PropertyType.Button)]
     public class Property
     {
         [JsonProperty("id")]

Src/Notion.Client/Models/Database/Properties/PropertyType.cs

@@ -71,5 +71,8 @@ public enum PropertyType
 
         [EnumMember(Value = "unique_id")]
         UniqueId,
+
+        [EnumMember(Value = "button")]
+        Button,
     }
 }

Src/Notion.Client/Models/PropertyValue/ButtonPropertyValue.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Newtonsoft.Json;
+
+namespace Notion.Client
+{
+    public class ButtonPropertyValue : PropertyValue
+    {
+        public override PropertyValueType Type => PropertyValueType.Button;
+
+        [JsonProperty("button")]
+        public ButtonValue Button { get; set; }
+
+        public class ButtonValue { }
+    }
+}

Src/Notion.Client/Models/PropertyValue/PropertyValue.cs

@@ -30,6 +30,7 @@ namespace Notion.Client
     [JsonSubtypes.KnownSubTypeAttribute(typeof(TitlePropertyValue), PropertyValueType.Title)]
     [JsonSubtypes.KnownSubTypeAttribute(typeof(UrlPropertyValue), PropertyValueType.Url)]
     [JsonSubtypes.KnownSubTypeAttribute(typeof(UniqueIdPropertyValue), PropertyValueType.UniqueId)]
+    [JsonSubtypes.KnownSubTypeAttribute(typeof(ButtonPropertyValue), PropertyValueType.Button)]
     [JsonSubtypes.KnownSubTypeAttribute(typeof(VerificationPropertyValue), PropertyValueType.Verification)]
     [SuppressMessage("ReSharper", "UnusedMember.Global")]
     [SuppressMessage("ReSharper", "UnassignedGetOnlyAutoProperty")]

Src/Notion.Client/Models/PropertyValue/PropertyValueType.cs

@@ -77,5 +77,8 @@ public enum PropertyValueType
 
         [EnumMember(Value = "verification")]
         Verification,
+
+        [EnumMember(Value = "button")]
+        Button,
     }
 }

Test/Notion.UnitTests/PagesClientTests.cs

@@ -222,7 +222,7 @@ public async Task TrashPageAsync()
 
         page.Id.Should().Be(pageId);
         page.InTrash.Should().BeTrue();
-        page.Properties.Should().HaveCount(2);
+        page.Properties.Should().HaveCount(3);
         var updatedProperty = page.Properties.First(x => x.Key == "In stock");
 
         var checkboxPropertyValue = (CheckboxPropertyItem)await _client.RetrievePagePropertyItemAsync(

Test/Notion.UnitTests/PropertyTests.cs

@@ -27,6 +27,7 @@ public class PropertyTests
     [InlineData(typeof(TitleProperty), PropertyType.Title)]
     [InlineData(typeof(UrlProperty), PropertyType.Url)]
     [InlineData(typeof(UniqueIdProperty), PropertyType.UniqueId)]
+    [InlineData(typeof(ButtonProperty),PropertyType.Button)]
     public void TestPropertyType(Type type, PropertyType expectedPropertyType)
     {
         var typeInstance = (Property)Activator.CreateInstance(type);
@@ -56,6 +57,7 @@ public void TestPropertyType(Type type, PropertyType expectedPropertyType)
     [InlineData(typeof(TitleProperty), "title")]
     [InlineData(typeof(UrlProperty), "url")]
     [InlineData(typeof(UniqueIdProperty), "unique_id")]
+    [InlineData(typeof(ButtonProperty), "button")]
     public void TestPropertyTypeText(Type type, string expectedPropertyType)
     {
         var typeInstance = (Property)Activator.CreateInstance(type);

Test/Notion.UnitTests/data/databases/DatabaseRetrieveResponse.json

@@ -90,6 +90,12 @@
         }
       }
     },
+    "SimpleButton": {
+      "id":"_ri%7C",
+      "name":"SimpleButton",
+      "type":"button",
+      "button": {}
+    },
     "Name": {
       "id": "title",
       "name": "Name",

Test/Notion.UnitTests/data/databases/DatabasesListResponse.json

@@ -81,6 +81,12 @@
             }
           }
         },
+        "SimpleButton": {
+          "id":"_ri%7C",
+          "name":"SimpleButton",
+          "type":"button",
+          "button": {}
+        },
         "Name": {
           "id": "title",
           "name": "Name",

Test/Notion.UnitTests/data/databases/DatabasesQueryResponse.json

@@ -45,6 +45,11 @@
           "id": "{>U;",
           "type": "checkbox",
           "checkbox": false
+        },
+        "Add Page Button": {
+          "id":"_ri%7C",
+          "type":"button",
+          "button": {}
         }
       }
     }

Test/Notion.UnitTests/data/pages/TrashPageResponse.json

@@ -11,6 +11,11 @@
       "type": "checkbox",
       "checkbox": true
     },
+    "Add Page Button": {
+        "id":"_ri%7C",
+        "type":"button",
+        "button": {}
+    },
     "Name": {
       "id": "title",
       "type": "title",