(core) When changing a table for a page widget, unset widget-linking to avoid invalid values.

Summary:
Previously, using "Change Widget" allowed one to change the underlying table,
but would keep the linking settings. This could allow invalid settings which
would sometimes lead to JS errors. These manifested in production as
"UserError: Query error: n is not a function".

- Unset linking settings in this case, to avoid invalid values.
- In case invalid values are encountered (e.g. saved previously), treat them as
  unset, to avoid JS errors.
- If an error does occur, report it with a stack trace.

Also, for testing, added 'selectBy' option to gristUtils helpers for using page-widget-picker.

Test Plan: Added test cases for resetting linking, and for ignoring invalid link settings.

Reviewers: alexmojaki

Reviewed By: alexmojaki

Differential Revision: https://phab.getgrist.com/D2993

app/client/components/BaseView.js

@@ -1,5 +1,3 @@
-/* global window */
-
 var _ = require('underscore');
 var ko = require('knockout');
 var moment = require('moment-timezone');
@@ -26,6 +24,7 @@ const {copyToClipboard} = require('app/client/lib/copyToClipboard');
 const {setTestState} = require('app/client/lib/testState');
 const {ExtraRows} = require('app/client/models/DataTableModelWithDiff');
 const {createFilterMenu} = require('app/client/ui/ColumnFilterMenu');
+const {LinkConfig} = require('app/client/ui/selectBy');
 const {encodeObject} = require("app/plugin/objtypes");
 
 /**
@@ -133,10 +132,16 @@ function BaseView(gristDoc, viewSectionModel, options) {
     let v = this.viewSection;
     let src = v.linkSrcSection();
     const filterByAllShown = v.optionsObj.prop('filterByAllShown');
-    return src.getRowId() ?
-      LinkingState.create.bind(LinkingState, this.gristDoc,
-        src, v.linkSrcCol().colId(), v, v.linkTargetCol().colId(), filterByAllShown()) :
-      null;
+    if (!src.getRowId()) {
+      return null;
+    }
+    try {
+      const config = new LinkConfig(v);
+      return LinkingState.create.bind(LinkingState, this.gristDoc, config, filterByAllShown());
+    } catch (err) {
+      console.warn(`Can't create LinkingState: ${err.message}`);
+      return null;
+    }
   }));
 
   this._linkingFilter = this.autoDispose(ko.computed(() => {
@@ -213,7 +218,7 @@ function BaseView(gristDoc, viewSectionModel, options) {
     const linkingFilter = this._linkingFilter();
     this._queryRowSource.makeQuery(linkingFilter.filters, linkingFilter.operations, (err) => {
       if (this.isDisposed()) { return; }
-      if (err) { window.gristNotify(`Query error: ${err.message}`); }
+      if (err) { reportError(err); }
       this.onTableLoaded();
     });
   }));

app/client/components/LinkingState.js

@@ -46,7 +46,8 @@ function isSummaryOf(summary, detail) {
  *    value at the cursor. The user can use column filters on srcSection to control what's shown
  *    in the linked tgtSection.
  */
-function LinkingState(gristDoc, srcSection, srcColId, tgtSection, tgtColId, byAllShown) {
+function LinkingState(gristDoc, linkConfig, byAllShown) {
+  const {srcSection, srcColId, tgtSection, tgtCol, tgtColId} = linkConfig;
   this._srcSection = srcSection;
 
   let srcTableModel = gristDoc.getTableModel(srcSection.table().tableId());
@@ -66,7 +67,6 @@ function LinkingState(gristDoc, srcSection, srcColId, tgtSection, tgtColId, byAl
   // A computed that evaluates to a filter function to use, or null if not filtering. If
   // filtering, depends on srcSection.activeRowId().
   if (tgtColId) {
-    const tgtCol = tgtSection.table().columns().all().find(c => c.colId() === tgtColId);
     const operations = {[tgtColId]: isRefListType(tgtCol.type()) ? 'intersects' : 'in'};
     if (byAllShown) {
       // (This is legacy code that isn't currently reachable)

app/client/ui/PageWidgetPicker.ts

@@ -371,6 +371,9 @@ export class PageWidgetSelect extends Disposable {
   }
 
   private _selectTable(tid: TableId) {
+    if (tid !== this._value.table.get()) {
+      this._value.link.set(NoLink);
+    }
     this._value.table.set(tid);
     this._closeSummarizePanel();
   }
@@ -386,6 +389,7 @@ export class PageWidgetSelect extends Disposable {
       if (tid !== this._value.table.get()) {
         this._value.columns.set([]);
         this._value.table.set(tid);
+        this._value.link.set(NoLink);
       }
       this._openSummarizePanel();
     }

app/client/ui/selectBy.ts

@@ -2,6 +2,7 @@ import { ColumnRec, DocModel, TableRec, ViewSectionRec } from 'app/client/models
 import { IPageWidget } from 'app/client/ui/PageWidgetPicker';
 import { getReferencedTableId } from 'app/common/gristTypes';
 import { IOptionFull } from 'grainjs';
+import * as assert from 'assert';
 
 // some unicode characters
 const BLACK_CIRCLE = '\u2022';
@@ -213,3 +214,48 @@ export function linkFromId(linkid: string) {
   const [srcSectionRef, srcColRef, targetColRef] = JSON.parse(linkid);
   return {srcSectionRef, srcColRef, targetColRef};
 }
+
+export class LinkConfig {
+  public readonly srcSection: ViewSectionRec;
+  public readonly tgtSection: ViewSectionRec;
+  // Note that srcCol and tgtCol may be the empty column records if that column is not used.
+  public readonly srcCol: ColumnRec;
+  public readonly tgtCol: ColumnRec;
+  public readonly srcColId: string|undefined;
+  public readonly tgtColId: string|undefined;
+
+  // The constructor throws an exception if settings are invalid. When used from inside a knockout
+  // computed, the constructor subscribes to all parts relevant for linking.
+  constructor(tgtSection: ViewSectionRec) {
+    this.tgtCol = tgtSection.linkTargetCol();
+    this.srcCol = tgtSection.linkSrcCol();
+    this.srcSection = tgtSection.linkSrcSection();
+    this.tgtSection = tgtSection;
+    this.srcColId = this.srcCol.colId();
+    this.tgtColId = this.tgtCol.colId();
+    this._assertValid();
+  }
+
+  // Check if section-linking configuration is valid, and throw exception if not.
+  private _assertValid(): void {
+    // Use null for unset cols (rather than an empty ColumnRec) for easier comparisons below.
+    const srcCol = this.srcCol?.getRowId() ? this.srcCol : null;
+    const tgtCol = this.tgtCol?.getRowId() ? this.tgtCol : null;
+    const srcTableId = (srcCol ? getReferencedTableId(srcCol.type.peek()) :
+      this.srcSection.table.peek().primaryTableId.peek());
+    const tgtTableId = (tgtCol ? getReferencedTableId(tgtCol.type.peek()) :
+      this.tgtSection.table.peek().primaryTableId.peek());
+    try {
+      assert(!tgtCol || tgtCol.parentId.peek() === this.tgtSection.tableRef.peek(), "tgtCol belongs to wrong table");
+      assert(!srcCol || srcCol.parentId.peek() === this.srcSection.tableRef.peek(), "srcCol belongs to wrong table");
+      assert(this.srcSection.getRowId() !== this.tgtSection.getRowId(), "srcSection links to itself");
+      assert(tgtTableId, "tgtCol not a valid reference");
+      assert(srcTableId, "srcCol not a valid reference");
+      assert(srcTableId === tgtTableId, "mismatched tableIds");
+    } catch (e) {
+      throw new Error(`LinkConfig invalid: ` +
+        `${this.srcSection.getRowId()}:${this.srcCol?.getRowId()}[${srcTableId}] -> ` +
+        `${this.tgtSection.getRowId()}:${this.tgtCol?.getRowId()}[${tgtTableId}]: ${e}`);
+    }
+  }
+}