Fixed wrongly loading auto_simplify value

pyzx/graph/base.py

@@ -754,7 +754,7 @@ def from_json(cls, js:Union[str,Dict[str,Any]]) -> BaseGraph[VT,ET]:
         """Converts the given .qgraph json string into a Graph.
         Works with the output of :meth:`to_json`."""
         from .jsonparser import json_to_graph
-        return json_to_graph(js, backend=cls.backend)
+        return json_to_graph(js)
 
     @classmethod
     def from_tikz(cls, tikz: str, warn_overlap:bool= True, fuse_overlap:bool = True, ignore_nonzx:bool = False) -> BaseGraph[VT,ET]:

pyzx/graph/jsonparser.py

@@ -351,7 +351,8 @@ def dict_to_graph(d: Dict[str,Any], backend: Optional[str]=None) -> BaseGraph:
     if g.backend == 'multigraph':
         if TYPE_CHECKING:
             assert isinstance(g, Multigraph)
-        g.set_auto_simplify(d.get('auto_simplify', True))
+        b = True if d.get('auto_simplify', True) in ('true', True) else False
+        g.set_auto_simplify(b)
     for v_d in d['vertices']:
         pos = v_d['pos']
         v = v_d['id']

tests/test_jsonparser.py

@@ -302,8 +302,16 @@ def test_load_multigraph_preserve_parallel_edges(self):
 
         d = g.to_dict()
         g2 = Graph.from_json(d)
+        self.assertTrue(g2.backend,'multigraph')
+        self.assertFalse(g2.get_auto_simplify())
         self.assertEqual(g.num_edges(), g2.num_edges())
 
+        js = json.dumps(d)
+        g3 = Graph.from_json(js)
+        self.assertTrue(g3.backend,'multigraph')
+        self.assertFalse(g3.get_auto_simplify())
+        self.assertEqual(g.num_edges(), g3.num_edges())
+
     def test_load_json_old_format(self):
         js = json.dumps(test_graph_old_format)
         g = Graph.from_json(js)