fix image api missing filename bug

image.go

@@ -132,7 +132,32 @@
 	return
 }
 
+// WrapReader wraps an io.Reader with filename and Content-type.
+func WrapReader(rdr io.Reader, filename string, contentType string) io.Reader {
+	return file{rdr, filename, contentType}
+}
+
+type file struct {
+	io.Reader
+	name        string
+	contentType string
+}
+
+func (f file) Name() string {
+	if f.name != "" {
+		return f.name
+	} else if named, ok := f.Reader.(interface{ Name() string }); ok {
+		return named.Name()
+	}
+	return ""
+}
+
+func (f file) ContentType() string {
+	return f.contentType
+}
+
 // ImageEditRequest represents the request structure for the image API.
+// Use WrapReader to wrap an io.Reader with filename and Content-type.
 type ImageEditRequest struct {
 	Image          io.Reader `json:"image,omitempty"`
 	Mask           io.Reader `json:"mask,omitempty"`
@@ -150,15 +175,15 @@
 	body := &bytes.Buffer{}
 	builder := c.createFormBuilder(body)
 
-	// image, filename is not required
+	// image, filename verification can be postponed
 	err = builder.CreateFormFileReader("image", request.Image, "")
 	if err != nil {
 		return
 	}
 
 	// mask, it is optional
 	if request.Mask != nil {
-		// mask, filename is not required
+		// filename verification can be postponed
 		err = builder.CreateFormFileReader("mask", request.Mask, "")
 		if err != nil {
 			return
@@ -206,6 +231,7 @@
 }
 
 // ImageVariRequest represents the request structure for the image API.
+// Use WrapReader to wrap an io.Reader with filename and Content-type.
 type ImageVariRequest struct {
 	Image          io.Reader `json:"image,omitempty"`
 	Model          string    `json:"model,omitempty"`
@@ -221,7 +247,7 @@
 	body := &bytes.Buffer{}
 	builder := c.createFormBuilder(body)
 
-	// image, filename is not required
+	// image, filename verification can be postponed
 	err = builder.CreateFormFileReader("image", request.Image, "")
 	if err != nil {
 		return

internal/form_builder.go

@@ -39,9 +39,18 @@
 }
 
 // CreateFormFileReader creates a form field with a file reader.
-// The filename in parameters can be an empty string.
-// The filename in Content-Disposition is required, But it can be an empty string.
+// The filename in Content-Disposition is required.
 func (fb *DefaultFormBuilder) CreateFormFileReader(fieldname string, r io.Reader, filename string) error {
+	if filename == "" {
+		if f, ok := r.(interface{ Name() string }); ok {
+			filename = f.Name()
+		}
+	}
+	var contentType string
+	if f, ok := r.(interface{ ContentType() string }); ok {
+		contentType = f.ContentType()
+	}
+
 	h := make(textproto.MIMEHeader)
 	h.Set(
 		"Content-Disposition",
@@ -51,6 +60,10 @@
 			escapeQuotes(filepath.Base(filename)),
 		),
 	)
+	// content type is optional, but it can be set
+	if contentType != "" {
+		h.Set("Content-Type", contentType)
+	}
 
 	fieldWriter, err := fb.writer.CreatePart(h)
 	if err != nil {