Add merge-dict conflict resolver spec and implementation in iOS

servers/ios/TestServer/Server/TestServer.swift

@@ -54,7 +54,7 @@ class TestServer : ObservableObject {
         setupRoutes()
     }
 
-    /// Implement API v1.2.1 (No support for start/stop listener - 1.1.0, and dynamic dataset - 1.1.1 yet)
+    /// Implement API v1.2.1 + Merge-Dict Conflict Resolver defined in 2.0.1.
     private func setupRoutes() {
         app.get("", use: Handlers.getRoot)
         app.post("newSession", use: Handlers.newSession)

servers/ios/TestServer/Utils/ReplicationConflictResolverFactory.swift

@@ -64,11 +64,61 @@ struct ReplicationConflictResolverFactory {
         }
     }
 
+    struct MergeDictResolver : AnyConflictResolver {
+        let property: String
+
+        func resolve(peerID: PeerID?, conflict: Conflict) -> Document? {
+            if conflict.localDocument == nil || conflict.remoteDocument == nil {
+                return nil
+            }
+
+            let doc = conflict.remoteDocument!.toMutable()
+
+            guard let localDict = conflict.localDocument!.dictionary(forKey: property) else {
+                return doc.setString("Both values are not dictionary", forKey: property)
+            }
+
+            guard let remoteDict = conflict.remoteDocument!.dictionary(forKey: property) else {
+                return doc.setString("Both values are not dictionary", forKey: property)
+            }
+
+            let mergedDict = MutableDictionaryObject()
+
+            for key in localDict {
+                mergedDict.setValue(localDict.value(forKey: key), forKey: key)
+            }
+
+            for key in remoteDict {
+                let remoteValue = remoteDict.value(forKey: key)!
+                if let curValue = mergedDict.value(forKey: key) {
+                    if !isEquals(curValue, remoteValue) {
+                        return doc.setString("Conflicting values found at key named '\(key)'", forKey: property)
+                    }
+                }
+                mergedDict.setValue(remoteValue, forKey: key)
+            }
+
+            return doc.setValue(mergedDict, forKey: property)
+        }
+
+        private func isEquals(_ lhs: Any, _ rhs: Any) -> Bool {
+            switch (lhs, rhs) {
+            case let (l as String, r as String): return l == r
+            case let (l as NSNumber, r as NSNumber): return l == r
+            case let (l as DictionaryObject, r as DictionaryObject): return l == r
+            case let (l as ArrayObject, r as ArrayObject): return l == r
+            case let (l as Blob, r as Blob): return l == r
+            default: return false
+            }
+        }
+    }
+
     private enum ConflictResolverType : String {
         case localWins = "local-wins"
         case removeWins = "remote-wins"
         case delete = "delete"
         case merge = "merge"
+        case mergeDict = "merge-dict"
     }
 
     static func getResolver(
@@ -90,6 +140,11 @@ struct ReplicationConflictResolverFactory {
                 throw TestServerError.badRequest("The property parameter is missing for the merge conflict resolver")
             }
             return ConflictResolver(MergeResolver(property: property))
+        case .mergeDict:
+            guard let property = params?["property"]?.value as? String else {
+                throw TestServerError.badRequest("The property parameter is missing for the merge-dict conflict resolver")
+            }
+            return ConflictResolver(MergeDictResolver(property: property))
         }
     }
 }

spec/api/api.yaml

@@ -46,6 +46,9 @@ info:
       ```
 
     Changes
+    2.0.1 (07/10/2025)
+    * Add Merge-Dict Conflict Resolver
+
     2.0.0 (06/13/2025)
     * This is a breaking change: CBLTest-API-Version is now "2"
     * deprecate dataset_version

spec/api/conflict-resolvers.md

@@ -40,3 +40,23 @@ For simplicity, restrict to top level keys.
 | :--------- | ----------- |
 | property| `<top level key>` |
 
+### merge-dict
+
+Performs a merge of the specified dictionary property by combining the two dictionaries. For simplicity, restrict to top level keys.
+
+* If one of the values is not a dictionary, the merged value will be set as:
+    ```
+    {"error": "Both values are not dictionary"}
+    ```
+* For any duplicated keys, the values must be the same, otherwise, the merged value will be set as:
+    ```
+    {"error": "Conflicting values found at key named 'key-name'"}
+    ```
+
+**name** : `merge-dict`
+
+**params** :
+
+| Key        | Value       |
+| :--------- | ----------- |
+| property| `<top level key>` |