small fixes to ENEX import

src/services/attributes.js

@@ -2,7 +2,6 @@
 
 const repository = require('./repository');
 const sql = require('./sql');
-const utils = require('./utils');
 const Attribute = require('../entities/attribute');
 
 const ATTRIBUTE_TYPES = [ 'label', 'relation' ];
@@ -146,6 +145,20 @@ function getBuiltinAttributeNames() {
         ]);
 }
 
+function sanitizeAttributeName(origName) {
+    let fixedName;
+
+    if (origName === '') {
+        fixedName = "unnamed";
+    }
+    else {
+        // any not allowed character should be replaced with underscore
+        fixedName = origName.replace(/[^\p{L}\p{N}_:]/ug, "_");
+    }
+
+    return fixedName;
+}
+
 module.exports = {
     getNotesWithLabel,
     getNotesWithLabels,
@@ -156,5 +169,6 @@ module.exports = {
     getAttributeNames,
     isAttributeType,
     isAttributeDangerous,
-    getBuiltinAttributeNames
+    getBuiltinAttributeNames,
+    sanitizeAttributeName
 };