Read Binary body with application/octet-stream Content-Type header

Author: EwenQuim

ctx.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"html/template"
+	"io"
 	"io/fs"
 	"log/slog"
 	"net/http"
@@ -124,8 +125,10 @@ type ContextNoBody struct {
 	readOptions readOptions
 }
 
-var _ ctx[any] = ContextNoBody{}        // Check that ContextNoBody implements Ctx.
-var _ context.Context = ContextNoBody{} // Check that ContextNoBody implements context.Context.
+var (
+	_ ctx[any]        = ContextNoBody{} // Check that ContextNoBody implements Ctx.
+	_ context.Context = ContextNoBody{} // Check that ContextNoBody implements context.Context.
+)
 
 func (c ContextNoBody) Body() (any, error) {
 	slog.Warn("this method should not be called. It probably happened because you passed the context to another controller.")
@@ -423,9 +426,20 @@ func body[B any](c ContextNoBody) (B, error) {
 	case "application/x-www-form-urlencoded", "multipart/form-data":
 		body, err = readURLEncoded[B](c.Req, c.readOptions)
 	case "application/xml":
-		return readXML[B](c.Req.Context(), c.Req.Body, c.readOptions)
+		body, err = readXML[B](c.Req.Context(), c.Req.Body, c.readOptions)
 	case "application/x-yaml":
-		return readYAML[B](c.Req.Context(), c.Req.Body, c.readOptions)
+		body, err = readYAML[B](c.Req.Context(), c.Req.Body, c.readOptions)
+	case "application/octet-stream":
+		// Read c.Req Body to bytes
+		bytes, err := io.ReadAll(c.Req.Body)
+		if err != nil {
+			return body, err
+		}
+		respBytes, ok := any(bytes).(B)
+		if !ok {
+			return body, fmt.Errorf("could not convert bytes to %T. To read binary data from the request, use []byte as the body type", body)
+		}
+		body = respBytes
 	case "application/json":
 		fallthrough
 	default:

ctx_test.go

@@ -170,6 +170,23 @@ func TestContext_Body(t *testing.T) {
 		require.Equal(t, 30, body.Age)
 	})
 
+	t.Run("can read JSON body with Content-Type application/json", func(t *testing.T) {
+		// Create new Reader
+		a := strings.NewReader(`{"name":"John","age":30}`)
+
+		// Test an http request
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest("GET", "http://example.com/foo", a)
+		r.Header.Add("Content-Type", "application/json")
+
+		c := NewContext[testStruct](w, r, readOptions{})
+
+		body, err := c.Body()
+		require.NoError(t, err)
+		require.Equal(t, "John", body.Name)
+		require.Equal(t, 30, body.Age)
+	})
+
 	t.Run("can read JSON body twice", func(t *testing.T) {
 		a := strings.NewReader(`{"name":"John","age":30}`)
 
@@ -251,6 +268,37 @@ func TestContext_Body(t *testing.T) {
 		require.Equal(t, 30, body.Age)
 	})
 
+	t.Run("can read bytes", func(t *testing.T) {
+		// Create new Reader with pure bytes from an image
+		a := bytes.NewReader([]byte(`image`))
+
+		// Test an http request
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest("GET", "http://example.com/foo", a)
+		r.Header.Add("Content-Type", "application/octet-stream")
+
+		c := NewContext[[]byte](w, r, readOptions{})
+		body, err := c.Body()
+		require.NoError(t, err)
+		require.Equal(t, []byte(`image`), body)
+	})
+
+	t.Run("cannot read bytes if expected type is different than bytes", func(t *testing.T) {
+		// Create new Reader with pure bytes from an image
+		a := bytes.NewReader([]byte(`image`))
+
+		// Test an http request
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest("GET", "http://example.com/foo", a)
+		r.Header.Add("Content-Type", "application/octet-stream")
+
+		c := NewContext[*struct{}](w, r, readOptions{})
+		body, err := c.Body()
+		require.Error(t, err)
+		require.ErrorContains(t, err, "use []byte as the body type")
+		require.Equal(t, (*struct{})(nil), body)
+	})
+
 	t.Run("can read XML body", func(t *testing.T) {
 		a := bytes.NewReader([]byte(`
 <TestStruct>

documentation/docs/guides/serialization.mdx

@@ -6,6 +6,23 @@ Fuego automatically serializes and deserializes inputs and outputs with standard
 
 <FlowChart selected="resp" />
 
+## Deserialize binary data
+
+If you just want to read the body of the request as a byte slice, you can use the `[]byte` receiver type.
+
+Don't forget to set the request `Content-Type` header to `application/octet-stream`. 
+
+```go
+fuego.Put(s, "/blob", func(c *fuego.ContextWithBody[[]byte]) (any, error) {
+	body, err := c.Body()
+	if err != nil {
+		return nil, err
+	}
+
+	return body, nil
+})
+```
+
 ## Custom serialization
 
 But you can also use the `Serialize` and `Deserialize` functions to manually serialize and deserialize data.