diff --git a/llms/mlx_lm/tuner/datasets.py b/llms/mlx_lm/tuner/datasets.py
index 3879fde5..05950077 100644
--- a/llms/mlx_lm/tuner/datasets.py
+++ b/llms/mlx_lm/tuner/datasets.py
@@ -2,48 +2,103 @@ import itertools
 import json
 import types
 from pathlib import Path
-from typing import Any, Dict, List, Optional
+from typing import Any, Dict, List, Union
 
 from transformers import PreTrainedTokenizer
 
 
 class DPODataset:
-    """
-    A dataset for DPO (Direct Preference Optimization) training that handles
-    prompt-chosen-rejected triplets in the format:
-    {"system": ..., "prompt": ..., "chosen": ..., "rejected": ...}
-    """
-
-    def __init__(self, data: List[Dict[str, str]], tokenizer: PreTrainedTokenizer,
-             prompt_key: str = "prompt", chosen_key: str = "chosen",
-             rejected_key: str = "rejected", system_key: str = "system"):
+    def __init__(
+        self,
+        data: List[Dict[str, Union[str, Dict, List]]],
+        tokenizer: PreTrainedTokenizer,
+        prompt_key: str = "prompt",
+        chosen_key: str = "chosen",
+        rejected_key: str = "rejected",
+        system_key: str = None
+    ):
         self._chosen_data = []
         self._rejected_data = []
         
         for d in data:
-            messages = (
-                [{"role": "system", "content": d[system_key]}] if system_key and system_key in d else []
-            )
-            messages.append({"role": "user", "content": d[prompt_key]})
+            # Get prompt content, preferring 'prompt' over 'question'
+            prompt_content = d.get(prompt_key, d.get("question", ""))
             
-            # Apply template once for each response type
-            base_messages = messages.copy()
-            chosen_messages = base_messages + [{"role": "assistant", "content": d[chosen_key]}]
-            rejected_messages = base_messages + [{"role": "assistant", "content": d[rejected_key]}]
+            if system_key and system_key in d:
+                base_messages = [{"role": "system", "content": d[system_key]}]
+                chosen_messages = base_messages + [{"role": "user", "content": prompt_content}]
+                rejected_messages = base_messages + [{"role": "user", "content": prompt_content}]
+                
+                # Handle chosen messages
+                if isinstance(d[chosen_key], str):
+                    chosen_messages.append({"role": "assistant", "content": d[chosen_key]})
+                elif isinstance(d[chosen_key], dict):
+                    if "messages" in d[chosen_key]:
+                        chosen_messages.extend(d[chosen_key]["messages"])
+                    else:
+                        chosen_messages.append({"role": "assistant", "content": d[chosen_key].get("content", "")})
+                elif isinstance(d[chosen_key], list):
+                    chosen_messages.extend(d[chosen_key])
+                
+                # Handle rejected messages
+                if isinstance(d[rejected_key], str):
+                    rejected_messages.append({"role": "assistant", "content": d[rejected_key]})
+                elif isinstance(d[rejected_key], dict):
+                    if "messages" in d[rejected_key]:
+                        rejected_messages.extend(d[rejected_key]["messages"])
+                    else:
+                        rejected_messages.append({"role": "assistant", "content": d[rejected_key].get("content", "")})
+                elif isinstance(d[rejected_key], list):
+                    rejected_messages.extend(d[rejected_key])
+                
+                chosen_text = tokenizer.apply_chat_template(chosen_messages)
+                rejected_text = tokenizer.apply_chat_template(rejected_messages)
             
-            self._chosen_data.append(tokenizer.apply_chat_template(chosen_messages))
-            self._rejected_data.append(tokenizer.apply_chat_template(rejected_messages))
+            else:
+                # Handle non-system message cases
+                chosen_content = self._extract_content(d[chosen_key])
+                rejected_content = self._extract_content(d[rejected_key])
+                
+                chosen_text = tokenizer.apply_chat_template([
+                    {"role": "user", "content": prompt_content},
+                    {"role": "assistant", "content": chosen_content},
+                ])
+                rejected_text = tokenizer.apply_chat_template([
+                    {"role": "user", "content": prompt_content},
+                    {"role": "assistant", "content": rejected_content},
+                ])
+            
+            self._chosen_data.append(chosen_text)
+            self._rejected_data.append(rejected_text)
+    
+    def _extract_content(self, data):
+        """Helper method to extract content from various data formats."""
+        if isinstance(data, str):
+            return data
+        elif isinstance(data, dict):
+            if "messages" in data:
+                last_message = data["messages"][-1]
+                return last_message.get("content", last_message.get("messages", ""))
+            return data.get("content", "")
+        elif isinstance(data, list):
+            last_message = data[-1]
+            if isinstance(last_message, dict):
+                if "content" in last_message:
+                    return last_message["content"]
+                elif "messages" in last_message:
+                    return last_message["messages"]
+            return last_message if isinstance(last_message, str) else ""
+        return ""
+
+    def __len__(self):
+        return len(self._chosen_data)
 
     def __getitem__(self, idx: int):
         return {
             "chosen": self._chosen_data[idx],
             "rejected": self._rejected_data[idx]
         }
-
-    def __len__(self):
-        return len(self._chosen_data)
-
-
+    
 class Dataset:
     """
     Light-weight wrapper to hold a dataset.