(core) Bug with empty, self-referencing RefList columns.

Summary:
If a table T contains a RefList:T showing RowId and there
are any empty cells, the table can't be removed.

Test Plan: Added new test

Reviewers: dsagal

Reviewed By: dsagal

Subscribers: dsagal

Differential Revision: https://phab.getgrist.com/D4215

sandbox/grist/useractions.py

@@ -1178,7 +1178,7 @@ class UserActions(object):
         # to strings containing comma-separated row IDs.
         # We need to get the values before changing the column type.
         table = self._engine.tables[table_id]
-        new_values = [",".join(map(str, row)) for row in self._get_column_values(col)]
+        new_values = [",".join(map(str, row or [])) for row in self._get_column_values(col)]
         self.ModifyColumn(table_id, col_id, dict(type="Text"))
         self.BulkUpdateRecord(table_id, list(table.row_ids), {col_id: new_values})
       return

test/nbrowser/ReferenceList.ts

@@ -10,14 +10,40 @@ describe('ReferenceList', function() {
 
   before(async function() {
     session = await gu.session().teamSite.login();
-    await session.tempDoc(cleanup, 'Favorite_Films.grist');
+  });
 
+  describe('other', function() {
+    it('allows to delete document with self reference', async function() {
+      const docId = await session.tempNewDoc(cleanup);
+      await gu.sendActions([
+        ['AddEmptyTable', 'Table2'],
+        ['ModifyColumn', 'Table1', 'B', {type: 'RefList:Table1'}],
+        ['AddRecord', 'Table1', null, {A: 'a'}],
+        ['AddRecord', 'Table1', null, {A: 'b', B: ["L", 1]}],
+        ['AddRecord', 'Table1', null, {A: 'c', B: ["L", 2]}],
+      ]);
+
+      // Now try to delete the table.
+      await gu.removeTable('Table1');
+      await gu.checkForErrors();
+
+      // Make sure table is deleted. Previously it ended with an engine error
+      // in the 'a' row which has NULL instead of a list of ids.
+      const api = session.createHomeApi().getDocAPI(docId);
+      const tables = await api.getRows('_grist_Tables');
+      assert.deepEqual(tables.tableId, ['Table2']);
+    });
+  });
+
+  describe('transforms', function() {
+
+    before(async function() {
+      await session.tempDoc(cleanup, 'Favorite_Films.grist');
       await gu.toggleSidePanel('right');
       await driver.find(".test-right-tab-pagewidget").click();
       await driver.find('.test-config-data').click();
     });
 
-  describe('transforms', function() {
     afterEach(() => gu.checkForErrors());
 
     it('should correctly transform references to reference lists', async function() {

test/nbrowser/gristUtils.ts

@@ -1016,6 +1016,13 @@ export async function sendActions(actions: UserAction[]) {
   await driver.manage().setTimeouts({
     script: 1000 * 2, /* 2 seconds, default is 0.5s */
   });
+
+  // Make quick test that we have a list of actions not just a single action, by checking
+  // if the first element is an array.
+  if (actions.length && !Array.isArray(actions[0])) {
+    throw new Error('actions argument should be a list of actions, not a single action');
+  }
+
   const result = await driver.executeAsyncScript(`
     const done = arguments[arguments.length - 1];
     const prom = gristDocPageModel.gristDoc.get().docModel.docData.sendActions(${JSON.stringify(actions)});