Fix join1:1 with empty prefix (#902) (#908)

* Fix prefix management

* Typo

---------

Co-authored-by: wlorenzetti <lorenzett@gis3w.it>
(cherry picked from commit bf673a3)

Co-authored-by: Walter Lorenzetti <lorenzetti@gis3w.it>

g3w-admin/qdjango/utils/data.py

@@ -391,20 +391,14 @@ def _getDataVectorjoins(self):
         try:
             vectorjoins = self.qgs_layer.vectorJoins()
 
-
-
             for order, join in enumerate(vectorjoins):
 
+
                 # Prefix management
-                # If sert custom prefix and the value is '', continue for cycle to avoid relation save
-                if layer_tree_vectorjoins[order].get('hasCustomPrefix') == '1' and join.prefix() == '':
-                    continue
+                if layer_tree_vectorjoins[order].get("hasCustomPrefix") == "1":
+                    prefix = join.prefix()
                 else:
-                    if layer_tree_vectorjoins[order].get("hasCustomPrefix") == "1":
-                        prefix = join.prefix()
-                    else:
-                        prefix = f"{join.joinLayer().name()}_"
-
+                    prefix = f"{join.joinLayer().name()}_"
 
                 ret.append(
                     {
@@ -1023,7 +1017,7 @@ def __init__(self, qgis_file, **kwargs):
 
         self.closeProject(**kwargs)
 
-        # register defaul validator
+        # register default validator
         for validator in self._defaultValidators:
             self.registerValidator(validator)