(core) Fix a bug that occurs after remaing a table containing a RefList column.

Summary:
This can happen after "Detach" is used on a summary table.
Includes a unittest reproducing the problem case.

Test Plan: Included unittest fails without the one-line tweak.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D2672

sandbox/grist/column.py

@@ -330,7 +330,7 @@ class BaseReferenceColumn(BaseColumn):
     # self._data may include values for non-existent rows; it works here because those values are
     # falsy, which makes them ignored by self._update_references).
     for row_id, value in enumerate(self._data):
-      if isinstance(value, int):
+      if self.type_obj.is_right_type(value):
         self._update_references(row_id, None, value)
 
   def sample_value(self):

sandbox/grist/test_reflist_rel.py

@@ -0,0 +1,102 @@
+"""
+This test replicates a bug involving a column conversion after a table rename in the presence of
+a RefList. A RefList column type today only appears as a result of detaching a summary table.
+"""
+import logger
+import test_engine
+from test_engine import Table, Column
+
+log = logger.Logger(__name__, logger.INFO)
+
+class TestRefListRelation(test_engine.EngineTestCase):
+  def test_ref_list_relation(self):
+    # Create two tables, the second referring to the first using a RefList and a Ref column.
+    self.apply_user_action(["AddTable", "TableA", [
+      {"id": "ColA", "type": "Text"}
+    ]])
+    self.apply_user_action(["AddTable", "TableB", [
+      {"id": "ColB", "type": "Text"},
+      {"id": "group", "type": "RefList:TableA", "isFormula": True,
+        "formula": "TableA.lookupRecords(ColA=$ColB)"},
+      {"id": "ref", "type": "Ref:TableA", "isFormula": True,
+        "formula": "TableA.lookupOne(ColA=$ColB)"},
+    ]])
+
+    # Populate the tables with some data.
+    self.apply_user_action(["BulkAddRecord", "TableA", [None]*4,
+      {"ColA": ["a", "b", "c", "d"]}])
+    self.apply_user_action(["BulkAddRecord", "TableB", [None]*3,
+      {"ColB": ["d", "b", "a"]}])
+
+    # Rename the second table. This causes some Column objects to be re-created and copied from
+    # the previous table instance. This logic had a bug.
+    self.apply_user_action(["RenameTable", "TableB", "TableC"])
+
+    # Let's see what we've set up here.
+    self.assertTables([
+      Table(1, "TableA", 1, 0, columns=[
+        Column(1, "manualSort", "ManualSortPos", False, "", 0),
+        Column(2, "ColA",   "Text", False, "", 0),
+      ]),
+      Table(2, "TableC", 2, 0, columns=[
+        Column(3, "manualSort", "ManualSortPos", False, "", 0),
+        Column(4, "ColB",   "Text", False, "", 0),
+        Column(5, "group",  "RefList:TableA", True, "TableA.lookupRecords(ColA=$ColB)", 0),
+        Column(6, "ref",    "Ref:TableA", True, "TableA.lookupOne(ColA=$ColB)", 0),
+      ]),
+    ])
+    self.assertTableData('TableA', cols="subset", data=[
+      [ "id", "ColA"],
+      [ 1,    "a",  ],
+      [ 2,    "b",  ],
+      [ 3,    "c",  ],
+      [ 4,    "d",  ],
+    ])
+    self.assertTableData('TableC', cols="subset", data=[
+      [ "id", "ColB", "group", "ref" ],
+      [ 1,    "d",    [4],     4 ],
+      [ 2,    "b",    [2],     2 ],
+      [ 3,    "a",    [1],     1 ],
+    ])
+
+    # Now when the logic was buggy, this sequence of action, as emitted by a user-initiated column
+    # conversion, triggered an internal exception. Ensure it no longer happens.
+    self.apply_user_action(
+        ['AddColumn', 'TableC', 'gristHelper_Transform', {
+          "type": 'Ref:TableA', "isFormula": True,
+          "formula": "grist.Reference.typeConvert($ColB, TableA, 'ColA')", "visibleCol": 2,
+        }])
+    self.apply_user_action(
+        ['SetDisplayFormula', 'TableC', None, 7, '$gristHelper_Transform.ColA'])
+    self.apply_user_action(
+        ['CopyFromColumn', 'TableC', 'gristHelper_Transform', 'ColB', '{"widget":"Reference"}'])
+    self.apply_user_action(
+        ['RemoveColumn', 'TableC', 'gristHelper_Transform'])
+
+    # Check what we have now.
+    self.assertTables([
+      Table(1, "TableA", 1, 0, columns=[
+        Column(1, "manualSort", "ManualSortPos", False, "", 0),
+        Column(2, "ColA",   "Text", False, "", 0),
+      ]),
+      Table(2, "TableC", 2, 0, columns=[
+        Column(3, "manualSort", "ManualSortPos", False, "", 0),
+        Column(4, "ColB",   "Ref:TableA", False, "", 0),
+        Column(5, "group",  "RefList:TableA", True, "TableA.lookupRecords(ColA=$ColB)", 0),
+        Column(6, "ref",    "Ref:TableA", True, "TableA.lookupOne(ColA=$ColB)", 0),
+        Column(9, "gristHelper_Display2", "Any", True, "$ColB.ColA", 0),
+      ]),
+    ])
+    self.assertTableData('TableA', cols="subset", data=[
+      [ "id", "ColA"],
+      [ 1,    "a",  ],
+      [ 2,    "b",  ],
+      [ 3,    "c",  ],
+      [ 4,    "d",  ],
+    ])
+    self.assertTableData('TableC', cols="subset", data=[
+      [ "id", "ColB", "gristHelper_Display2", "group", "ref" ],
+      [ 1,      4,    "d",                    [],     0 ],
+      [ 2,      2,    "b",                    [],     0 ],
+      [ 3,      1,    "a",                    [],     0 ],
+    ])