fix(postgres): improve AGE agtype parsing and simplify error logging

- Fix JSON parsing errors caused by :: characters in data content
- Implement precise agtype string parsing using rfind() to separate JSON content from type identifiers
- Add robust error handling for malformed JSON in graph data

lightrag/kg/postgres_impl.py

@@ -1905,53 +1905,101 @@ class PGGraphStorage(BaseGraphStorage):
                 the dictionary key is the field name and the value is the
                 value converted to a python type
         """
+
+        @staticmethod
+        def parse_agtype_string(agtype_str: str) -> tuple[str, str]:
+            """
+            Parse agtype string precisely, separating JSON content and type identifier
+
+            Args:
+                agtype_str: String like '{"json": "content"}::vertex'
+
+            Returns:
+                (json_content, type_identifier)
+            """
+            if not isinstance(agtype_str, str) or "::" not in agtype_str:
+                return agtype_str, ""
+
+            # Find the last :: from the right, which is the start of type identifier
+            last_double_colon = agtype_str.rfind("::")
+
+            if last_double_colon == -1:
+                return agtype_str, ""
+
+            # Separate JSON content and type identifier
+            json_content = agtype_str[:last_double_colon]
+            type_identifier = agtype_str[last_double_colon + 2 :]
+
+            return json_content, type_identifier
+
+        @staticmethod
+        def safe_json_parse(json_str: str, context: str = "") -> dict:
+            """
+            Safe JSON parsing with simplified error logging
+            """
+            try:
+                return json.loads(json_str)
+            except json.JSONDecodeError as e:
+                logger.error(f"JSON parsing failed ({context}): {e}")
+                logger.error(f"Raw data (first 100 chars): {repr(json_str[:100])}")
+                logger.error(f"Error position: line {e.lineno}, column {e.colno}")
+                return None
+
         # result holder
         d = {}
 
         # prebuild a mapping of vertex_id to vertex mappings to be used
         # later to build edges
         vertices = {}
+
+        # First pass: preprocess vertices
         for k in record.keys():
             v = record[k]
-            # agtype comes back '{key: value}::type' which must be parsed
             if isinstance(v, str) and "::" in v:
                 if v.startswith("[") and v.endswith("]"):
-                    if "::vertex" not in v:
-                        continue
-                    v = v.replace("::vertex", "")
-                    vertexes = json.loads(v)
-                    for vertex in vertexes:
-                        vertices[vertex["id"]] = vertex.get("properties")
+                    # Handle vertex arrays
+                    json_content, type_id = parse_agtype_string(v)
+                    if type_id == "vertex":
+                        vertexes = safe_json_parse(
+                            json_content, f"vertices array for {k}"
+                        )
+                        if vertexes:
+                            for vertex in vertexes:
+                                vertices[vertex["id"]] = vertex.get("properties")
                 else:
-                    dtype = v.split("::")[-1]
-                    v = v.split("::")[0]
-                    if dtype == "vertex":
-                        vertex = json.loads(v)
-                        vertices[vertex["id"]] = vertex.get("properties")
+                    # Handle single vertex
+                    json_content, type_id = parse_agtype_string(v)
+                    if type_id == "vertex":
+                        vertex = safe_json_parse(json_content, f"single vertex for {k}")
+                        if vertex:
+                            vertices[vertex["id"]] = vertex.get("properties")
 
-        # iterate returned fields and parse appropriately
+        # Second pass: process all fields
         for k in record.keys():
             v = record[k]
             if isinstance(v, str) and "::" in v:
                 if v.startswith("[") and v.endswith("]"):
-                    if "::vertex" in v:
-                        v = v.replace("::vertex", "")
-                        d[k] = json.loads(v)
-
-                    elif "::edge" in v:
-                        v = v.replace("::edge", "")
-                        d[k] = json.loads(v)
+                    # Handle array types
+                    json_content, type_id = parse_agtype_string(v)
+                    if type_id in ["vertex", "edge"]:
+                        parsed_data = safe_json_parse(
+                            json_content, f"array {type_id} for field {k}"
+                        )
+                        d[k] = parsed_data if parsed_data is not None else None
                     else:
-                        print("WARNING: unsupported type")
-                        continue
-
+                        logger.warning(f"Unknown array type: {type_id}")
+                        d[k] = None
                 else:
-                    dtype = v.split("::")[-1]
-                    v = v.split("::")[0]
-                    if dtype == "vertex":
-                        d[k] = json.loads(v)
-                    elif dtype == "edge":
-                        d[k] = json.loads(v)
+                    # Handle single objects
+                    json_content, type_id = parse_agtype_string(v)
+                    if type_id in ["vertex", "edge"]:
+                        parsed_data = safe_json_parse(
+                            json_content, f"single {type_id} for field {k}"
+                        )
+                        d[k] = parsed_data if parsed_data is not None else None
+                    else:
+                        # May be other types of agtype data, keep as is
+                        d[k] = v
             else:
                 d[k] = v  # Keep as string