Quote handles in GraphView Graphviz output

The Graph View wrote each Gramps handle into the Graphviz/DOT graph as an
unquoted node id (add_node, add_link and the subgraph cluster name).
Handles may be any string up to 50 characters, and Gramps-Web creates
UUIDv4 handles containing hyphens. Graphviz splits an unquoted id at the
hyphen, so the node, edge and cluster names were mangled and the view
rendered blank.

Quote the handle at the three sites where it is emitted as a DOT id, so a
hyphenated handle is treated as a single id. A quoted name beginning with
"cluster" is still treated as a cluster by Graphviz, so grouping is
unchanged. The core Graphviz reports already quote their node ids.

Fixes #13832.

Author: eduralph

GraphView/graphview.py

@@ -3321,9 +3321,12 @@ def add_link(self, id1, id2, style="", head="", tail="", comment="",
         Add a link between two nodes.
         Gramps handles are used as nodes but need to be prefixed
         with an underscore because Graphviz does not like IDs
-        that begin with a number.
+        that begin with a number. The id is quoted because handles are
+        arbitrary schema-valid strings: Gramps-Web creates UUIDv4 handles
+        containing hyphens, which an unquoted Graphviz ID would split on
+        (bug 13832).
         """
-        self.write('  _%s -> _%s' % (id1, id2))
+        self.write('  "_%s" -> "_%s"' % (id1, id2))
 
         boldok = False
         if id1 in self.current_list:
@@ -3390,7 +3393,10 @@ def add_node(self, node_id, label, shape="", color="",
             text += ' URL="%s"' % url
 
         text += " ]"
-        self.write(' _%s %s;\n' % (node_id, text))
+        # Quote the id: handles are arbitrary schema-valid strings, and
+        # Gramps-Web creates UUIDv4 handles with hyphens that an unquoted
+        # Graphviz ID would split on, blanking the graph (bug 13832).
+        self.write(' "_%s" %s;\n' % (node_id, text))
 
     def add_tags_tooltip(self, handle, tag_list):
         """
@@ -3407,7 +3413,11 @@ def start_subgraph(self, graph_id):
         Opens a subgraph which is used to keep together related nodes
         on the graph.
         """
-        self.write('\n subgraph cluster_%s\n' % graph_id)
+        # Quote the name: graph_id is a handle (see bug 13832); a UUIDv4
+        # handle with hyphens would break an unquoted subgraph name.
+        # Graphviz still treats a quoted name beginning with "cluster" as
+        # a cluster subgraph.
+        self.write('\n subgraph "cluster_%s"\n' % graph_id)
         self.write(' {\n')
         # no border around subgraph (#0002176)
         self.write('  style="invis";\n')

GraphView/tests/__init__.py

@@ -0,0 +1,101 @@
+#
+# Gramps - a GTK+/GNOME based genealogy program
+#
+# Copyright (C) 2026  Eduard Ralph
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, see <https://www.gnu.org/licenses/>.
+#
+
+"""
+Unit tests for Graphviz node-id quoting in the GraphView addon (bug 13832).
+"""
+
+import unittest
+from io import StringIO
+
+# GraphView imports Gtk/GooCanvas at module load; on a host without those
+# typelibs (or a display) the import raises. Skip cleanly there rather than
+# erroring, so the suite stays runnable without the addon's requires_gi deps.
+try:
+    import gi
+
+    gi.require_version("Gtk", "3.0")
+    from GraphView.graphview import DotSvgGenerator
+
+    _IMPORT_ERROR = None
+except Exception as err:  # pragma: no cover - depends on host gi stack
+    DotSvgGenerator = None
+    _IMPORT_ERROR = err
+
+
+# A Gramps-Web UUIDv4 handle (hyphens) vs. a desktop handle (no hyphens).
+HYPHEN_HANDLE = "22e6b2a0-269e-4c58-8e27-0c38b2ef5a10"
+PLAIN_HANDLE = "fe4861b093015ddcbb08044be02"
+
+
+# ------------------------------------------------------------
+#
+# DotHandleQuotingTest
+#
+# ------------------------------------------------------------
+@unittest.skipIf(
+    DotSvgGenerator is None,
+    "GraphView import unavailable (gi/GooCanvas/display): %s" % (_IMPORT_ERROR,),
+)
+class DotHandleQuotingTest(unittest.TestCase):
+    """
+    The DOT generator emits Gramps handles as node ids. Handles are
+    arbitrary schema-valid strings (<=50 chars); Gramps-Web creates
+    UUIDv4 handles containing hyphens. An unquoted Graphviz id is split at
+    the first hyphen, so the node/edge/cluster name is mangled and the
+    Graph View blanks (bug 13832). Every handle written into the DOT must
+    therefore be quoted.
+    """
+
+    def _generator(self):
+        # Bypass __init__ (which needs a live dbstate/view); the DOT-writing
+        # methods only touch the attributes set up here.
+        gen = DotSvgGenerator.__new__(DotSvgGenerator)
+        gen.dot = StringIO()
+        gen.current_list = set()
+        gen.colors = {"link_color": "#000000"}
+        return gen
+
+    def test_add_node_quotes_hyphenated_handle(self):
+        gen = self._generator()
+        gen.add_node(HYPHEN_HANDLE, "Some Label")
+        out = gen.dot.getvalue()
+        self.assertIn('"_%s"' % HYPHEN_HANDLE, out)
+
+    def test_add_node_quotes_plain_handle(self):
+        gen = self._generator()
+        gen.add_node(PLAIN_HANDLE, "Some Label")
+        out = gen.dot.getvalue()
+        self.assertIn('"_%s"' % PLAIN_HANDLE, out)
+
+    def test_add_link_quotes_both_endpoints(self):
+        gen = self._generator()
+        gen.add_link(HYPHEN_HANDLE, PLAIN_HANDLE)
+        out = gen.dot.getvalue()
+        self.assertIn('"_%s" -> "_%s"' % (HYPHEN_HANDLE, PLAIN_HANDLE), out)
+
+    def test_start_subgraph_quotes_cluster_name(self):
+        gen = self._generator()
+        gen.start_subgraph(HYPHEN_HANDLE)
+        out = gen.dot.getvalue()
+        self.assertIn('"cluster_%s"' % HYPHEN_HANDLE, out)
+
+
+if __name__ == "__main__":
+    unittest.main()