Don't return content in response if it's unchanged

backend/sync_server/src/server/responses.rs

@@ -1,18 +1,40 @@
 use schemars::JsonSchema;
 use serde::{self, Serialize};
 
-use crate::database::models::{DocumentVersionWithoutContent, VaultUpdateId};
+use crate::database::models::{DocumentVersion, DocumentVersionWithoutContent, VaultUpdateId};
 
+/// Response to a ping request.
 #[derive(Debug, Clone, Serialize, JsonSchema)]
 #[serde(rename_all = "camelCase")]
 pub struct PingResponse {
+    /// Semantic version of the server.
     pub server_version: String,
+
+    /// Whether the client is authenticated based on the sent Authorization
+    /// header.
     pub is_authenticated: bool,
 }
 
+/// Response to a fetch latest documents request.
 #[derive(Debug, Clone, Serialize, JsonSchema)]
 #[serde(rename_all = "camelCase")]
 pub struct FetchLatestDocumentsResponse {
     pub latest_documents: Vec<DocumentVersionWithoutContent>,
+
+    /// The update ID of the latest document in the response.
     pub last_update_id: VaultUpdateId,
 }
+
+/// Response to a create/update document request.
+#[derive(Debug, Clone, Serialize, JsonSchema)]
+#[serde(tag = "type")]
+pub enum DocumentUpdateResponse {
+    /// Returned when the created/updated document's content is the same as was
+    /// sent in the create/update request and thus the response doesn't contain
+    /// the content because the client must already have it.
+    FastForwardUpdate(DocumentVersionWithoutContent),
+
+    /// Returned when the created/updated document's content is different from
+    /// what was sent in the create/update request.
+    MergingUpdate(DocumentVersion),
+}