diff --git a/libs/client-api/src/http_chat.rs b/libs/client-api/src/http_chat.rs
index 8648697e..8afdfefe 100644
--- a/libs/client-api/src/http_chat.rs
+++ b/libs/client-api/src/http_chat.rs
@@ -298,8 +298,17 @@ impl QuestionStream {
 }
 
 pub enum QuestionStreamValue {
-  Answer { value: String },
-  Metadata { value: serde_json::Value },
+  Answer {
+    value: String,
+  },
+  /// Metadata is a JSON array object. its structure as below:
+  /// ```json
+  /// [
+  ///   {"id": "xx", "source": "", "name": "" }
+  /// ]
+  Metadata {
+    value: serde_json::Value,
+  },
 }
 impl Stream for QuestionStream {
   type Item = Result<QuestionStreamValue, AppResponseError>;
diff --git a/libs/database-entity/src/dto.rs b/libs/database-entity/src/dto.rs
index bbfc28e3..a13b7050 100644
--- a/libs/database-entity/src/dto.rs
+++ b/libs/database-entity/src/dto.rs
@@ -682,7 +682,8 @@ impl ChatMetadataData {
     match self.content_type {
       ChatMetadataContentType::Text => self.content.len() == self.size as usize,
       ChatMetadataContentType::Markdown => self.content.len() == self.size as usize,
-      _ => true,
+      ChatMetadataContentType::Unknown => false,
+      ChatMetadataContentType::PDF => false,
     }
   }
 }
@@ -692,8 +693,7 @@ pub enum ChatMetadataContentType {
   Unknown,
   Text,
   Markdown,
-  Pdf,
-  Custom(String),
+  PDF,
 }
 
 impl Display for ChatMetadataContentType {
@@ -702,8 +702,7 @@ impl Display for ChatMetadataContentType {
       ChatMetadataContentType::Unknown => write!(f, "unknown"),
       ChatMetadataContentType::Text => write!(f, "txt"),
       ChatMetadataContentType::Markdown => write!(f, "markdown"),
-      ChatMetadataContentType::Pdf => write!(f, "pdf"),
-      ChatMetadataContentType::Custom(custom) => write!(f, "{}", custom),
+      ChatMetadataContentType::PDF => write!(f, "pdf"),
     }
   }
 }