Add support for single-value headers

src/modules/Elsa.Http/Activities/SendHttpRequestBase.cs

@@ -1,9 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Net.Http;
 using System.Net.Http.Headers;
-using System.Threading.Tasks;
 using Elsa.Extensions;
 using Elsa.Http.ActivityOptionProviders;
 using Elsa.Http.ContentWriters;

src/modules/Elsa.Http/Extensions/HttpActivityExecutionContextExtensions.cs

@@ -1,9 +1,3 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
 using Elsa.Http.Contracts;
 using Elsa.Workflows.Core;
 using Elsa.Workflows.Core.Models;
@@ -20,7 +14,7 @@ internal static class HttpActivityExecutionContextExtensions
 
         if (contentParser == null)
             return null;
-        
+
         return await contentParser.ReadAsync(content, returnType, cancellationToken);
     }
 
@@ -28,19 +22,12 @@ internal static class HttpActivityExecutionContextExtensions
     {
         var value = context.Get(input.MemoryBlockReference());
 
-        if (value is IDictionary<string, string[]> dictionary1)
-            return dictionary1;
-
-        if (value is IDictionary<string, string> dictionary2)
-            return dictionary2.ToDictionary(x => x.Key, x => new[] { x.Value });
-
-        if (value is IDictionary<string, object> dictionary3)
-            return dictionary3.ToDictionary(
-                pair => pair.Key,
-                pair => pair.Value is ICollection<object> collection
-                    ? collection.Select(x => x.ToString()!).ToArray()
-                    : new[] { pair.Value.ToString()! });
-
-        return Array.Empty<KeyValuePair<string, string[]>>();
+        return value switch
+        {
+            IDictionary<string, string[]> dictionary1 => dictionary1,
+            IDictionary<string, string> dictionary2 => dictionary2.ToDictionary(x => x.Key, x => new[] { x.Value }),
+            IDictionary<string, object> dictionary3 => dictionary3.ToDictionary(pair => pair.Key, pair => pair.Value is ICollection<object> collection ? collection.Select(x => x.ToString()!).ToArray() : new[] { pair.Value.ToString()! }),
+            _ => Array.Empty<KeyValuePair<string, string[]>>()
+        };
     }
 }

src/modules/Elsa.Http/Models/HttpRequestHeaders.cs

@@ -1,14 +1,17 @@
-using System.Collections.Generic;
+using System.Text.Json.Serialization;
 using Elsa.Extensions;
+using Elsa.Http.Serialization;
 
 namespace Elsa.Http.Models;
 
+/// <summary>
+/// Represents the headers of an HTTP request.
+/// </summary>
+[JsonConverter(typeof(HttpRequestHeadersConverter))]
 public class HttpRequestHeaders : Dictionary<string, string[]>
 {
-    public string? ContentType => this.GetValue("content-type")?[0];
-}
-
-public class HttpResponseHeaders : Dictionary<string, string[]>
-{
+    /// <summary>
+    /// Gets the content type of the request.
+    /// </summary>
     public string? ContentType => this.GetValue("content-type")?[0];
 }

src/modules/Elsa.Http/Models/HttpResponseHeaders.cs

@@ -0,0 +1,14 @@
+using Elsa.Extensions;
+
+namespace Elsa.Http.Models;
+
+/// <summary>
+/// Represents the headers of an HTTP response.
+/// </summary>
+public class HttpResponseHeaders : Dictionary<string, string[]>
+{
+    /// <summary>
+    /// Gets the content type of the response.
+    /// </summary>
+    public string? ContentType => this.GetValue("content-type")?[0];
+}

src/modules/Elsa.Http/Serialization/HttpRequestHeadersConverter.cs

@@ -0,0 +1,70 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using Elsa.Http.Models;
+
+namespace Elsa.Http.Serialization;
+
+/// <summary>
+/// A custom JSON converter for <see cref="HttpRequestHeaders"/> that supports both single and multiple values.
+/// </summary>
+public class HttpRequestHeadersConverter : JsonConverter<HttpRequestHeaders>
+{
+    /// <inheritdoc />
+    public override HttpRequestHeaders Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        if (reader.TokenType != JsonTokenType.StartObject)
+            throw new JsonException("Expected StartObject token");
+
+        var headers = new HttpRequestHeaders();
+
+        while (reader.Read())
+        {
+            if (reader.TokenType == JsonTokenType.EndObject)
+                return headers;
+
+            if (reader.TokenType != JsonTokenType.PropertyName)
+                throw new JsonException("Expected a PropertyName token");
+
+            var key = reader.GetString()!;
+            reader.Read();
+
+            // If the next token is not a StartArray token, then we expect a String token.
+            switch (reader.TokenType)
+            {
+                case JsonTokenType.StartArray:
+                {
+                    var values = new List<string>();
+                    while (reader.Read() && reader.TokenType != JsonTokenType.EndArray) values.Add(reader.GetString()!);
+                    headers.Add(key, values.ToArray());
+                    break;
+                }
+                case JsonTokenType.String:
+                {
+                    var singleValue = reader.GetString()!;
+                    headers.Add(key, new[] { singleValue });
+                    break;
+                }
+                default:
+                    throw new JsonException("Expected a String or StartArray token");
+            }
+        }
+
+        throw new JsonException("Expected an EndObject token");
+    }
+
+    /// <inheritdoc />
+    public override void Write(Utf8JsonWriter writer, HttpRequestHeaders value, JsonSerializerOptions options)
+    {
+        writer.WriteStartObject();
+
+        foreach (var header in value)
+        {
+            writer.WritePropertyName(header.Key);
+            writer.WriteStartArray();
+            foreach (var headerValue in header.Value) writer.WriteStringValue(headerValue);
+            writer.WriteEndArray();
+        }
+
+        writer.WriteEndObject();
+    }
+}

src/modules/Elsa.Http/Serialization/HttpStatusCodeCaseForWorkflowInstanceConverter.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 using Elsa.Http.Models;