Create a "unique(ish)" hash for barcode data

InvenTree/InvenTree/api.py

@@ -85,6 +85,7 @@ class BarcodeScanView(APIView):
                         }
 
                     response['plugin'] = plugin.get_name()
+                    response['hash'] = plugin.hash()
 
                     break
 

InvenTree/plugins/barcode/barcode.py

@@ -1,5 +1,7 @@
 # -*- coding: utf-8 -*-
 
+import hashlib
+
 import plugins.plugin as plugin
 
 
@@ -18,9 +20,17 @@ class BarcodePlugin(plugin.InvenTreePlugin):
         Calculate a hash for the barcode data.
         This is supposed to uniquely identify the barcode contents,
         at least within the bardcode sub-type.
+
+        The default implementation simply returns an MD5 hash of the barcode data,
+        encoded to a string.
+
+        This may be sufficient for most applications, but can obviously be overridden
+        by a subclass.
+
         """
 
-        return ""
+        hash = hashlib.md5(str(self.data).encode())
+        return str(hash.hexdigest())
 
     def validate(self):
         """