Issue #153: serialize multi-link link rels always as JSON array

.gitignore

@@ -115,3 +115,4 @@ WebApi.Hal*.nupkg
 .vscode/
 .DS_Store
 *~
+*.bak

WebApi.Hal.Tests/HalResourceListTests.one_item_organisation_list_get_json_test.approved.txt

@@ -3,9 +3,11 @@
     "self": {
       "href": "/api/organisations"
     },
-    "organisation": {
-      "href": "/api/organisations/1"
-    }
+    "organisation": [
+      {
+        "href": "/api/organisations/1"
+      }
+    ]
   },
   "_embedded": {
     "organisation": [

WebApi.Hal.Tests/HalResourceTest.cs

@@ -1,7 +1,14 @@
-using System.Buffers;
+using System;
+using System.Buffers;
 using System.IO;
+using System.Linq;
 using Assent;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.ObjectPool;
 using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
 using WebApi.Hal.Tests.Representations;
 using Xunit;
 
@@ -112,5 +119,148 @@ public void organisation_get_xml_test()
                 this.Assent(serialisedResult);
             }
         } 
+
+        [Fact]
+        public void organisation_get_json_with_multi_link_linkrel()
+        {
+            // arrange
+            var mediaFormatter = new JsonHalMediaTypeOutputFormatter(
+                new JsonSerializerSettings { Formatting = Formatting.Indented }, ArrayPool<char>.Shared);
+            var resourceWithAppPath = new OrganisationWithLinkTitleRepresentation(1, "Org Name");
+            resourceWithAppPath.Links.Add(new Link("multi-rel-with-single-link", "~/api/organisations/test")
+            {
+                IsMultiLink = true
+            });
+            resourceWithAppPath.Links.Add(new Link("multi-rel-with-multiple-links", "~/api/organisations/test1")
+            {
+                IsMultiLink = true
+            });
+            resourceWithAppPath.Links.Add(new Link("multi-rel-with-multiple-links", "~/api/organisations/test2")
+            {
+                IsMultiLink = true
+            });
+            resourceWithAppPath.Links.Add(new Link("multi-rel-with-multiple-links-with-is-multilink-false", "~/api/organisations/test-f1"));
+            resourceWithAppPath.Links.Add(new Link("multi-rel-with-multiple-links-with-is-multilink-false", "~/api/organisations/test-f2"));
+
+            // act
+            using (var stream = new StringWriter())
+            {
+                mediaFormatter.WriteObject(stream, resourceWithAppPath);
+
+                string serialisedResult = stream.ToString();
+
+                // assert
+                this.Assent(serialisedResult);
+            }
+        }
+
+        public class OrganisationRepresentationWithEmbeddedResources : OrganisationWithAppPathRepresentation
+        {
+            public OrganisationRepresentationWithEmbeddedResources(int id, string name) : base(id, name)
+            {
+            }
+
+            public TestRepresentation[] EmbeddedMultiResource { get; set; }
+
+            public TestRepresentation EmbeddedSingleResource { get; set; }
+        }
+
+        public class TestRepresentation : Representation
+        {
+        }
+
+        [Fact]
+        public void organisation_get_json_with_multi_link_embedded()
+        {
+            // arrange
+            var mediaFormatter = new JsonHalMediaTypeOutputFormatter(
+                new JsonSerializerSettings { Formatting = Formatting.Indented }, ArrayPool<char>.Shared);
+            var org = new OrganisationRepresentationWithEmbeddedResources(1, "Org Name");
+
+            org.EmbeddedSingleResource = new TestRepresentation
+            {
+                Rel = "single-resource",
+                Href = "~/single"
+            };
+            org.EmbeddedMultiResource = new[] { new TestRepresentation
+            {
+                Rel = "multi-resource",
+                Href = "~/multi"
+            } };
+
+            // act
+            using (var stream = new StringWriter())
+            {
+                mediaFormatter.WriteObject(stream, org);
+
+                string serialisedResult = stream.ToString();
+
+                // assert
+                this.Assent(serialisedResult);
+            }
+        }
+
+        private class JsonHalMediaTypeInputFormatterWithCreateSerializer : JsonHalMediaTypeInputFormatter
+        {
+            public JsonHalMediaTypeInputFormatterWithCreateSerializer(ILogger logger, JsonSerializerSettings serializerSettings, ArrayPool<char> charPool, ObjectPoolProvider objectPoolProvider, MvcOptions mvcOptions, MvcJsonOptions mvcJsonOptions) 
+                : base(logger, serializerSettings, charPool, objectPoolProvider, mvcOptions, mvcJsonOptions)
+            {
+            }
+
+            public new JsonSerializer CreateJsonSerializer()
+            {
+                return base.CreateJsonSerializer();
+            }
+        }
+
+        [Fact]
+        public void organisation_parse_json_with_multi_link_linkrel()
+        {
+            // arrange
+            var mediaFormatter = new JsonHalMediaTypeOutputFormatter(
+                new JsonSerializerSettings { Formatting = Formatting.Indented }, ArrayPool<char>.Shared);
+            var resourceWithAppPath = new OrganisationWithLinkTitleRepresentation(1, "Org Name");
+            resourceWithAppPath.Links.Add(new Link("multi-rel-with-single-link", "~/api/organisations/test")
+            {
+                IsMultiLink = true
+            });
+            resourceWithAppPath.Links.Add(new Link("multi-rel-with-multiple-links", "~/api/organisations/test1")
+            {
+                IsMultiLink = true
+            });
+            resourceWithAppPath.Links.Add(new Link("multi-rel-with-multiple-links", "~/api/organisations/test2")
+            {
+                IsMultiLink = true
+            });
+            resourceWithAppPath.Links.Add(new Link("multi-rel-with-multiple-links-with-is-multilink-false", "~/api/organisations/test1"));
+            resourceWithAppPath.Links.Add(new Link("multi-rel-with-multiple-links-with-is-multilink-false", "~/api/organisations/test2"));
+
+            string serialisedResource;
+            // serialize
+            using (var stream = new StringWriter())
+            {
+                mediaFormatter.WriteObject(stream, resourceWithAppPath);
+
+                serialisedResource = stream.ToString();
+            }
+
+            // parse again
+            var inputFormatter = new JsonHalMediaTypeInputFormatterWithCreateSerializer(
+                NullLogger.Instance,
+                new JsonSerializerSettings { Formatting = Formatting.Indented }, ArrayPool<char>.Shared,
+                new DefaultObjectPoolProvider(), new MvcOptions(), new MvcJsonOptions());
+            var inputSerializer = inputFormatter.CreateJsonSerializer();
+            using (var stream = new StringReader(serialisedResource))
+            {
+                using (var jsonReader = new JsonTextReader(stream))
+                {
+                    var parsedResource = inputSerializer.Deserialize<OrganisationWithLinkTitleRepresentation>(jsonReader);
+                    Assert.True(parsedResource.Links.Where(l => l.Rel == "multi-rel-with-single-link").All(l => l.IsMultiLink));
+                    Assert.True(parsedResource.Links.Where(l => l.Rel == "multi-rel-with-multiple-links").All(l => l.IsMultiLink));
+                    Assert.True(parsedResource.Links.Where(l => l.Rel == "multi-rel-with-multiple-links-with-is-multilink-false").All(l => l.IsMultiLink));
+                    Assert.True(parsedResource.Links.Where(l => l.Rel == "someRel").All(l => !l.IsMultiLink));
+                }
+            }
+        }
     }
 }

WebApi.Hal.Tests/HalResourceTest.organisation_get_json_with_multi_link_embedded.approved.txt

@@ -0,0 +1,35 @@
+{
+  "Id": 1,
+  "Name": "Org Name",
+  "_links": {
+    "self": {
+      "href": "/api/organisations/1"
+    },
+    "multi-resource": [
+      {
+        "href": "/multi"
+      }
+    ],
+    "single-resource": {
+      "href": "/single"
+    }
+  },
+  "_embedded": {
+    "multi-resource": [
+      {
+        "_links": {
+          "self": {
+            "href": "/multi"
+          }
+        }
+      }
+    ],
+    "single-resource": {
+      "_links": {
+        "self": {
+          "href": "/single"
+        }
+      }
+    }
+  }
+}

WebApi.Hal.Tests/HalResourceTest.organisation_get_json_with_multi_link_linkrel.approved.txt

@@ -0,0 +1,31 @@
+{
+  "Id": 1,
+  "Name": "Org Name",
+  "_links": {
+    "multi-rel-with-single-link": [
+      {
+        "href": "/api/organisations/test"
+      }
+    ],
+    "multi-rel-with-multiple-links": [
+      {
+        "href": "/api/organisations/test1"
+      },
+      {
+        "href": "/api/organisations/test2"
+      }
+    ],
+    "multi-rel-with-multiple-links-with-is-multilink-false": [
+      {
+        "href": "/api/organisations/test-f1"
+      },
+      {
+        "href": "/api/organisations/test-f2"
+      }
+    ],
+    "somerel": {
+      "href": "someHref",
+      "title": "someTitle"
+    }
+  }
+}

WebApi.Hal/JsonConverters/LinksConverter.cs

@@ -24,13 +24,15 @@ public override void WriteJson(JsonWriter writer, object value, JsonSerializer s
 
                 writer.WritePropertyName(rel.Key);
 
-                if ((count > 1) || (rel.Key == Link.RelForCuries))
+                bool serializeAsArray = (count > 1) || (rel.Any(l => l.IsMultiLink)) || (rel.Key == Link.RelForCuries);
+
+                if (serializeAsArray)
                     writer.WriteStartArray();
 
                 foreach (var link in rel)
                     WriteLink(writer, link);
 
-                if ((count > 1) || (rel.Key == Link.RelForCuries))
+                if ((count > 1) || (rel.Any(l => l.IsMultiLink)) || (rel.Key == Link.RelForCuries))
                     writer.WriteEndArray();
             }
 

WebApi.Hal/JsonConverters/ResourceConverter.cs

@@ -161,6 +161,7 @@ static void CreateLinks(JProperty rel, IResource resource)
                     foreach (var link in arr.Select(item => item.ToObject<Link>()))
                     {
                         link.Rel = rel.Name;
+                        link.IsMultiLink = true;
                         resource.Links.Add(link);
                     }
             }

WebApi.Hal/Link.cs

@@ -76,6 +76,7 @@ public string Rel
         public string Name { get; set; }
         public string Profile { get; set; }
         public string HrefLang { get; set; }
+        public bool IsMultiLink { get; set; }
 
         public bool IsTemplated => !string.IsNullOrEmpty(Href) && isTemplatedRegex.IsMatch(Href);
 

WebApi.Hal/Representation.cs

@@ -146,7 +146,10 @@ private void ProcessPropertyValue(IHypermediaResolver resolver, List<CuriesLink>
                 var link = representation.ToLink(resolver);
 
                 if (link != null)
+                {
+                    link.IsMultiLink = true;
                     Links.Add(link); // add a link to embedded to the container ...
+                }
             }
 
             Embedded.Add(embeddedResource);

WebApi.Hal/WebApi.Hal.csproj

@@ -4,15 +4,13 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0</TargetFrameworks>
-    <Version>3.1.0</Version>
-+    <PackageVersion>3.1.0</PackageVersion>
+    <Version>3.2.0</Version>
+    <PackageVersion>3.2.0</PackageVersion>
     <Copyright>Copyright © Jake Ginnivan 2018</Copyright>
     <Description>Adds support for the Hal Media Type (and Hypermedia) to Asp.net</Description>
     <ProjectUrl>https://github.com/JakeGinnivan/WebApi.Hal</ProjectUrl>
     <IsPackable>true</IsPackable>
-    <PackageReleaseNotes>3.10 updates to support multithreaded usage
-+    3.0.0 first .net standard release
-+    </PackageReleaseNotes>
+    <PackageReleaseNotes>3.2.0 ability to mark a link-rel as multi-link to ensure that it always serialzies to an array, even if there's only one link at runtime</PackageReleaseNotes>
   </PropertyGroup>
 
   <ItemGroup>