addDefaultHeaders method

void addDefaultHeaders(HttpHeaders headers, MediaType? contentType)

Adds default headers to the HTTP message if not already present.

Parameters

• headers: The HTTP headers to modify
• contentType: The content type to set if no Content-Type is present

Header Strategy

This method follows a conservative approach:

• Only sets Content-Type if not already specified
• Respects existing headers to avoid overriding user-set values
• Uses the provided contentType or falls back to first supported media type

Example

@override
Future<void> write(Object object, MediaType? contentType, HttpOutputMessage outputMessage) async {
  final headers = outputMessage.getHeaders();
  
  // Set default headers if needed
  addDefaultHeaders(headers, contentType);
  
  // Now proceed with writing the body
  await writeInternal(object, outputMessage);
}

Implementation

void addDefaultHeaders(HttpHeaders headers, MediaType? contentType) {
  if (headers.getContentType() == null && contentType != null) {
    headers.setContentType(contentType);
  }
}