From 956e07e877d5618dda176aedbce00c1bfee69ad5 Mon Sep 17 00:00:00 2001
From: Dmitry S <dsagal+git@gmail.com>
Date: Fri, 5 Feb 2021 09:49:23 -0500
Subject: [PATCH] (core) When filter-linking by a reference column, update the
 filter-linking when the value in that column changes

Test Plan: Added a test case for the fix.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D2724
---
 app/client/components/LinkingState.js | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/app/client/components/LinkingState.js b/app/client/components/LinkingState.js
index f62681a6..76541e76 100644
--- a/app/client/components/LinkingState.js
+++ b/app/client/components/LinkingState.js
@@ -48,7 +48,8 @@ function isSummaryOf(summary, detail) {
 function LinkingState(gristDoc, srcSection, srcColId, tgtSection, tgtColId, byAllShown) {
   this._srcSection = srcSection;
 
-  let srcTableData = gristDoc.getTableModel(srcSection.table().tableId()).tableData;
+  let srcTableModel = gristDoc.getTableModel(srcSection.table().tableId());
+  let srcTableData = srcTableModel.tableData;
 
   // Function from srcRowId (i.e. srcSection.activeRowId()) to the source value. It is used for
   // filtering or for cursor positioning, depending on the setting of tgtCol.
@@ -78,11 +79,22 @@ function LinkingState(gristDoc, srcSection, srcColId, tgtSection, tgtColId, byAl
         }
         return {[tgtColId]: Array.from(srcValues)};
       }));
+    } else if (srcColId) {
+      let srcRowModel = this.autoDispose(srcTableModel.createFloatingRowModel());
+      let srcCell = srcRowModel.cells[srcColId];
+      // If no srcCell, linking is broken; do nothing. This shouldn't happen, but may happen
+      // transiently while the separate linking-related observables get updated.
+      if (srcCell) {
+        this.filterColValues = this.autoDispose(ko.computed(() => {
+          const srcRowId = srcSection.activeRowId();
+          srcRowModel.assign(srcRowId);
+          return {[tgtColId]: [srcCell()]};
+        }));
+      }
     } else {
       this.filterColValues = this.autoDispose(ko.computed(() => {
         const srcRowId = srcSection.activeRowId();
-        const srcValue = srcValueFunc(srcRowId);
-        return {[tgtColId]: [srcValue]};
+        return {[tgtColId]: [srcRowId]};
       }));
     }
   } else if (isSummaryOf(srcSection.table(), tgtSection.table())) {