Serialize explode value properly on parameters with style "form"

mapitman · mapitman · commit 34b0f77734f4 · 2019-04-26T16:56:46.000-07:00
When a parameter has the style set to "form" and explode set to false, the v3 serializer will not write out the value for explode. Swagger UI then defaults the explode value to true, since it is not specified and that is the correct default value when the style is set to "form". The OpenAPI spec for this is right around here: https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.0.md#fixed-fields-10
diff --git a/src/Microsoft.OpenApi/Models/OpenApiParameter.cs b/src/Microsoft.OpenApi/Models/OpenApiParameter.cs
@@ -177,7 +177,7 @@ public void SerializeAsV3WithoutReference(IOpenApiWriter writer)
             writer.WriteProperty(OpenApiConstants.Style, Style?.GetDisplayName());
 
             // explode
-            writer.WriteProperty(OpenApiConstants.Explode, Explode, false);
+            writer.WriteProperty(OpenApiConstants.Explode, Explode, Style.HasValue && Style.Value == ParameterStyle.Form);
 
             // allowReserved
             writer.WriteProperty(OpenApiConstants.AllowReserved, AllowReserved, false);
diff --git a/test/Microsoft.OpenApi.Tests/Models/OpenApiParameterTests.cs b/test/Microsoft.OpenApi.Tests/Models/OpenApiParameterTests.cs
@@ -5,6 +5,7 @@
 using System.Globalization;
 using System.IO;
 using FluentAssertions;
+using Microsoft.OpenApi.Any;
 using Microsoft.OpenApi.Extensions;
 using Microsoft.OpenApi.Models;
 using Microsoft.OpenApi.Writers;
@@ -58,6 +59,50 @@ public class OpenApiParameterTests
             }
         };
 
+        public static OpenApiParameter ParameterWithFormStyleAndExplodeFalse = new OpenApiParameter
+        {
+            Name = "name1",
+            In = ParameterLocation.Query,
+            Description = "description1",
+            Style = ParameterStyle.Form,
+            Explode = false,
+            Schema = new OpenApiSchema
+            {
+                Type = "array",
+                Items = new OpenApiSchema
+                {
+                    Enum = new List<IOpenApiAny>
+                    {
+                        new OpenApiString("value1"),
+                        new OpenApiString("value2")
+                    }
+                }
+            }
+
+        };
+
+        public static OpenApiParameter ParameterWithFormStyleAndExplodeTrue = new OpenApiParameter
+        {
+            Name = "name1",
+            In = ParameterLocation.Query,
+            Description = "description1",
+            Style = ParameterStyle.Form,
+            Explode = true,
+            Schema = new OpenApiSchema
+            {
+                Type = "array",
+                Items = new OpenApiSchema
+                {
+                    Enum = new List<IOpenApiAny>
+                    {
+                        new OpenApiString("value1"),
+                        new OpenApiString("value2")
+                    }
+                }
+            }
+
+        };
+
         public static OpenApiParameter AdvancedHeaderParameterWithSchemaReference = new OpenApiParameter
         {
             Name = "name1",
@@ -309,5 +354,74 @@ public void SerializeParameterWithSchemaTypeObjectAsV2JsonWorks()
             expected = expected.MakeLineBreaksEnvironmentNeutral();
             actual.Should().Be(expected);
         }
+
+        [Fact]
+        public void SerializeParameterWithFormStyleAndExplodeFalseWorks()
+        {
+            // Arrange
+            var outputStringWriter = new StringWriter(CultureInfo.InvariantCulture);
+            var writer = new OpenApiJsonWriter(outputStringWriter);
+            var expected =
+                @"{
+  ""name"": ""name1"",
+  ""in"": ""query"",
+  ""description"": ""description1"",
+  ""style"": ""form"",
+  ""explode"": false,
+  ""schema"": {
+    ""type"": ""array"",
+    ""items"": {
+      ""enum"": [
+        ""value1"",
+        ""value2""
+      ]
+    }
+  }
+}";
+
+            // Act
+            ParameterWithFormStyleAndExplodeFalse.SerializeAsV3WithoutReference(writer);
+            writer.Flush();
+            var actual = outputStringWriter.GetStringBuilder().ToString();
+
+            // Assert
+            actual = actual.MakeLineBreaksEnvironmentNeutral();
+            expected = expected.MakeLineBreaksEnvironmentNeutral();
+            actual.Should().Be(expected);
+        }
+
+        [Fact]
+        public void SerializeParameterWithFormStyleAndExplodeTrueWorks()
+        {
+            // Arrange
+            var outputStringWriter = new StringWriter(CultureInfo.InvariantCulture);
+            var writer = new OpenApiJsonWriter(outputStringWriter);
+            var expected =
+                @"{
+  ""name"": ""name1"",
+  ""in"": ""query"",
+  ""description"": ""description1"",
+  ""style"": ""form"",
+  ""schema"": {
+    ""type"": ""array"",
+    ""items"": {
+      ""enum"": [
+        ""value1"",
+        ""value2""
+      ]
+    }
+  }
+}";
+
+            // Act
+            ParameterWithFormStyleAndExplodeTrue.SerializeAsV3WithoutReference(writer);
+            writer.Flush();
+            var actual = outputStringWriter.GetStringBuilder().ToString();
+
+            // Assert
+            actual = actual.MakeLineBreaksEnvironmentNeutral();
+            expected = expected.MakeLineBreaksEnvironmentNeutral();
+            actual.Should().Be(expected);
+        }
     }
 }
