Serverside sort and limit for vendor and filaments

spoolman/database/utils.py

@@ -2,7 +2,33 @@
 
 from enum import Enum
 
+import sqlalchemy
+
+from spoolman.database import models
+
 
 class SortOrder(Enum):
     ASC = 1
     DESC = 2
+
+
+def parse_nested_field(base_obj: type[models.Base], field: str) -> sqlalchemy.Column:
+    """Parse a nested field string into a sqlalchemy field object."""
+    fields = field.split(".")
+    if not hasattr(base_obj, fields[0]):
+        raise ValueError(f"Invalid field name '{field}'")
+
+    if fields[0] == "filament" and len(fields) == 1:
+        raise ValueError("No field specified for filament")
+    if fields[0] == "filament":
+        return parse_nested_field(models.Filament, ".".join(fields[1:]))
+
+    if fields[0] == "vendor" and len(fields) == 1:
+        raise ValueError("No field specified for vendor")
+    if fields[0] == "vendor":
+        return parse_nested_field(models.Vendor, ".".join(fields[1:]))
+
+    if len(fields) > 1:
+        raise ValueError(f"Field '{fields[0]}' does not have any nested fields")
+
+    return getattr(base_obj, fields[0])