fix admin user persm

devices/models.py

@@ -15,10 +15,19 @@ def validate_mac_address(value):
     return value
 
 
+def normalize_mac(value):
+    """Canonicalize any accepted MAC format to upper-case, dash-separated
+    form (e.g. "aa:bb:cc:dd:ee:ff" and "aabbccddeeff" -> "AA-BB-CC-DD-EE-FF").
+    Used so uniqueness is enforced on one canonical representation."""
+    hex_only = re.sub(r"[^0-9A-Fa-f]", "", value or "").upper()
+    return "-".join(hex_only[i : i + 2] for i in range(0, len(hex_only), 2))
+
+
 class Device(models.Model):
     name = models.CharField(max_length=255)
     mac = models.CharField(
         max_length=255,
+        unique=True,
         validators=[
             validate_mac_address,
         ],