Add binary format

Author: alexeyzimarev

src/RestSharp/Enum.cs

@@ -27,7 +27,7 @@ public enum ParameterType {
 /// <summary>
 /// Data formats
 /// </summary>
-public enum DataFormat { Json, Xml, None }
+public enum DataFormat { Json, Xml, Binary, None }
 
 /// <summary>
 /// HTTP method to use when making requests

src/RestSharp/Parameters/BodyParameter.cs

@@ -18,6 +18,9 @@ namespace RestSharp;
 public record BodyParameter : Parameter {
     public BodyParameter(string? name, object value, string contentType, DataFormat dataFormat = DataFormat.None)
         : base(name, Ensure.NotNull(value, nameof(value)), ParameterType.RequestBody, false) {
+        if (dataFormat == DataFormat.Binary && value is not byte[]) {
+            throw new ArgumentException("Binary data format needs a byte array as value");
+        }
         ContentType = contentType;
         DataFormat  = dataFormat;
     }
@@ -26,6 +29,11 @@ public BodyParameter(string? name, object value, string contentType, DataFormat
     /// Body parameter data type
     /// </summary>
     public DataFormat DataFormat { get; init; } = DataFormat.None;
+    
+    /// <summary>
+    /// Custom content encoding
+    /// </summary>
+    public string? ContentEncoding { get; init; }
 }
 
 public record XmlParameter : BodyParameter {

src/RestSharp/Request/RequestContent.cs

@@ -68,10 +68,23 @@ void AddFiles() {
 
     HttpContent Serialize(BodyParameter body) {
         return body.DataFormat switch {
-            DataFormat.None => new StringContent(body.Value!.ToString()!, _client.Options.Encoding, body.ContentType),
-            _               => GetSerialized()
+            DataFormat.None   => new StringContent(body.Value!.ToString()!, _client.Options.Encoding, body.ContentType),
+            DataFormat.Binary => GetBinary(),
+            _                 => GetSerialized()
         };
 
+        HttpContent GetBinary() {
+            var byteContent = new ByteArrayContent((body.Value as byte[])!);
+            byteContent.Headers.ContentType = MediaTypeHeaderValue.Parse(body.ContentType);
+
+            if (body.ContentEncoding != null) {
+                byteContent.Headers.ContentEncoding.Clear();
+                byteContent.Headers.ContentEncoding.Add(body.ContentEncoding);
+            }
+
+            return byteContent;
+        }
+
         HttpContent GetSerialized() {
             if (!_client.Serializers.TryGetValue(body.DataFormat, out var serializerRecord))
                 throw new InvalidDataContractException(
@@ -120,7 +133,7 @@ void AddBody(bool hasPostParameters) {
         }
 
         if (_client.Options.DisableCharset) {
-            Content.Headers.ContentType.CharSet = "";
+            Content.Headers.ContentType!.CharSet = "";
         }
     }