(core) Show count of formula errors in the column config in the right-side panel.

Summary:
- Cache the count by column, factoring out ColumnCache from
  ColumnACIndexes, which uses a similar pattern.
- Update error counts in response to column selection and to data changes.

Test Plan: Adds a test case for the new message

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D2780

app/client/models/ColumnACIndexes.ts

@@ -9,11 +9,10 @@
  * It is currently used for auto-complete in the ReferenceEditor widget.
  */
 import {ACIndex, ACIndexImpl} from 'app/client/lib/ACIndex';
+import {ColumnCache} from 'app/client/models/ColumnCache';
 import {UserError} from 'app/client/models/errors';
 import {TableData} from 'app/client/models/TableData';
-import {DocAction} from 'app/common/DocActions';
-import {isBulkUpdateRecord, isUpdateRecord} from 'app/common/DocActions';
-import {getSetMapValue, localeCompare, nativeCompare} from 'app/common/gutil';
+import {localeCompare, nativeCompare} from 'app/common/gutil';
 import {BaseFormatter} from 'app/common/ValueFormatter';
 
 export interface ICellItem {
@@ -24,13 +23,9 @@ export interface ICellItem {
 
 
 export class ColumnACIndexes {
-  private _cachedColIndexes = new Map<string, ACIndex<ICellItem>>();
+  private _columnCache = new ColumnCache<ACIndex<ICellItem>>(this._tableData);
 
-  constructor(private _tableData: TableData) {
-    // Whenever a table action is applied, consider invalidating per-column caches.
-    this._tableData.tableActionEmitter.addListener(this._invalidateCache, this);
-    this._tableData.dataLoadedEmitter.addListener(this._clearCache, this);
-  }
+  constructor(private _tableData: TableData) {}
 
   /**
    * Returns the column index for the given column, using a cached one if available.
@@ -38,7 +33,7 @@ export class ColumnACIndexes {
    * getColACIndex() is called for the same column with the the same formatter.
    */
   public getColACIndex(colId: string, formatter: BaseFormatter): ACIndex<ICellItem> {
-    return getSetMapValue(this._cachedColIndexes, colId, () => this._buildColACIndex(colId, formatter));
+    return this._columnCache.getValue(colId, () => this._buildColACIndex(colId, formatter));
   }
 
   private _buildColACIndex(colId: string, formatter: BaseFormatter): ACIndex<ICellItem> {
@@ -56,23 +51,6 @@ export class ColumnACIndexes {
     items.sort(itemCompare);
     return new ACIndexImpl(items);
   }
-
-  private _invalidateCache(action: DocAction): void {
-    if (isUpdateRecord(action) || isBulkUpdateRecord(action)) {
-      // If the update only affects existing records, only invalidate affected columns.
-      const colValues = action[3];
-      for (const colId of Object.keys(colValues)) {
-        this._cachedColIndexes.delete(colId);
-      }
-    } else {
-      // For add/delete actions and all schema changes, drop the cache entirelly to be on the safe side.
-      this._clearCache();
-    }
-  }
-
-  private _clearCache(): void {
-    this._cachedColIndexes.clear();
-  }
 }
 
 function itemCompare(a: ICellItem, b: ICellItem) {

app/client/models/ColumnCache.ts

@@ -0,0 +1,42 @@
+/**
+ * Implements a cache of values computed from the data in a Grist column.
+ */
+import {TableData} from 'app/client/models/TableData';
+import {DocAction} from 'app/common/DocActions';
+import {isBulkUpdateRecord, isUpdateRecord} from 'app/common/DocActions';
+import {getSetMapValue} from 'app/common/gutil';
+
+export class ColumnCache<T> {
+  private _cachedColIndexes = new Map<string, T>();
+
+  constructor(private _tableData: TableData) {
+    // Whenever a table action is applied, consider invalidating per-column caches.
+    this._tableData.tableActionEmitter.addListener(this._invalidateCache, this);
+    this._tableData.dataLoadedEmitter.addListener(this._clearCache, this);
+  }
+
+  /**
+   * Returns the cached value for the given column, or calculates and caches the value using the
+   * provided calc() function.
+   */
+  public getValue(colId: string, calc: () => T): T {
+    return getSetMapValue(this._cachedColIndexes, colId, calc);
+  }
+
+  private _invalidateCache(action: DocAction): void {
+    if (isUpdateRecord(action) || isBulkUpdateRecord(action)) {
+      // If the update only affects existing records, only invalidate affected columns.
+      const colValues = action[3];
+      for (const colId of Object.keys(colValues)) {
+        this._cachedColIndexes.delete(colId);
+      }
+    } else {
+      // For add/delete actions and all schema changes, drop the cache entirely to be on the safe side.
+      this._clearCache();
+    }
+  }
+
+  private _clearCache(): void {
+    this._cachedColIndexes.clear();
+  }
+}

app/client/models/TableData.ts

@@ -2,8 +2,11 @@
  * TableData maintains a single table's data.
  */
 import {ColumnACIndexes} from 'app/client/models/ColumnACIndexes';
+import {ColumnCache} from 'app/client/models/ColumnCache';
 import {DocData} from 'app/client/models/DocData';
 import {DocAction, ReplaceTableData, TableDataAction, UserAction} from 'app/common/DocActions';
+import {isRaisedException} from 'app/common/gristTypes';
+import {countIf} from 'app/common/gutil';
 import {ColTypeMap, TableData as BaseTableData} from 'app/common/TableData';
 import {BaseFormatter} from 'app/common/ValueFormatter';
 import {Emitter} from 'grainjs';
@@ -19,6 +22,8 @@ export class TableData extends BaseTableData {
 
   public readonly columnACIndexes = new ColumnACIndexes(this);
 
+  private _columnErrorCounts = new ColumnCache<number|undefined>(this);
+
   /**
    * Constructor for TableData.
    * @param {DocData} docData: The root DocData object for this document.
@@ -92,6 +97,17 @@ export class TableData extends BaseTableData {
     return ret;
   }
 
+  /**
+   * Counts and returns the number of error values in the given column. The count is cached to
+   * keep it faster for large tables, and the cache is cleared as needed on changes to the table.
+   */
+  public countErrors(colId: string): number|undefined {
+    return this._columnErrorCounts.getValue(colId, () => {
+      const values = this.getColValues(colId);
+      return values && countIf(values, isRaisedException);
+    });
+  }
+
   /**
    * Sends an array of table-specific action to the server to be applied. The tableId should be
    * omitted from each `action` parameter and will be inserted automatically.

app/client/ui/FieldConfig.ts

@@ -7,9 +7,10 @@ import {textInput} from 'app/client/ui2018/editableLabel';
 import {cssIconButton, icon} from 'app/client/ui2018/icons';
 import {menu, menuItem} from 'app/client/ui2018/menus';
 import {sanitizeIdent} from 'app/common/gutil';
-import {Computed, dom, fromKo, IDisposableOwner, Observable, styled} from 'grainjs';
+import {Computed, dom, fromKo, MultiHolder, Observable, styled, subscribe} from 'grainjs';
+import debounce = require('lodash/debounce');
 
-export function buildNameConfig(owner: IDisposableOwner, origColumn: ColumnRec) {
+export function buildNameConfig(owner: MultiHolder, origColumn: ColumnRec) {
   const untieColId = origColumn.untieColIdFromLabel;
 
   const editedLabel = Observable.create(owner, '');
@@ -50,10 +51,11 @@ export function buildNameConfig(owner: IDisposableOwner, origColumn: ColumnRec)
 type BuildEditor = (cellElem: Element) => void;
 
 export function buildFormulaConfig(
-  owner: IDisposableOwner, origColumn: ColumnRec, gristDoc: GristDoc, buildEditor: BuildEditor
+  owner: MultiHolder, origColumn: ColumnRec, gristDoc: GristDoc, buildEditor: BuildEditor
 ) {
   const clearColumn = () => gristDoc.clearColumns([origColumn.id.peek()]);
   const convertToData = () => gristDoc.convertFormulasToData([origColumn.id.peek()]);
+  const errorMessage = createFormulaErrorObs(owner, gristDoc, origColumn);
 
   return dom.maybe(use => {
       if (!use(origColumn.id)) { return null; }    // Invalid column, show nothing.
@@ -73,7 +75,10 @@ export function buildFormulaConfig(
         );
       }
       function buildFormulaRow(placeholder = 'Enter formula') {
-        return cssRow(dom.create(buildFormula, origColumn, buildEditor, placeholder));
+        return [
+          cssRow(dom.create(buildFormula, origColumn, buildEditor, placeholder)),
+          dom.maybe(errorMessage, errMsg => cssRow(cssError(errMsg), testId('field-error-count'))),
+        ];
       }
       if (type === "empty") {
         return [
@@ -104,7 +109,7 @@ export function buildFormulaConfig(
   );
 }
 
-function buildFormula(owner: IDisposableOwner, column: ColumnRec, buildEditor: BuildEditor, placeholder: string) {
+function buildFormula(owner: MultiHolder, column: ColumnRec, buildEditor: BuildEditor, placeholder: string) {
   return cssFieldFormula(column.formula, {placeholder, maxLines: 2},
     dom.cls('formula_field_sidepane'),
     cssFieldFormula.cls('-disabled', column.disableModify),
@@ -115,6 +120,52 @@ function buildFormula(owner: IDisposableOwner, column: ColumnRec, buildEditor: B
   );
 }
 
+/**
+ * Create and return an observable for the count of errors in a column, which gets updated in
+ * response to changes in origColumn and in user data.
+ */
+function createFormulaErrorObs(owner: MultiHolder, gristDoc: GristDoc, origColumn: ColumnRec) {
+  const errorMessage = Observable.create(owner, '');
+
+  // Count errors in origColumn when it's a formula column. Counts get cached by the
+  // tableData.countErrors() method, and invalidated on relevant data changes.
+  function countErrors() {
+    if (owner.isDisposed()) { return; }
+    const tableData = gristDoc.docData.getTable(origColumn.table.peek().tableId.peek());
+    if (tableData && origColumn.isRealFormula.peek()) {
+      const colId = origColumn.colId.peek();
+      const numCells = tableData.getColValues(colId)?.length || 0;
+      const numErrors = tableData.countErrors(colId) || 0;
+      errorMessage.set(
+        (numErrors === 0) ? '' :
+        (numCells === 1) ? `Error in the cell` :
+        (numErrors === numCells) ? `Errors in all ${numErrors} cells` :
+        `Errors in ${numErrors} of ${numCells} cells`
+      );
+    } else {
+      errorMessage.set('');
+    }
+  }
+
+  // Debounce the count calculation to defer it to the end of a bundle of actions.
+  const debouncedCountErrors = debounce(countErrors, 0);
+
+  // If there is an update to the data in the table, count errors again. Since the same UI is
+  // reused when different page widgets are selected, we need to re-create this subscription
+  // whenever the selected table changes. We use a Computed to both react to changes and dispose
+  // the previous subscription when it changes.
+  Computed.create(owner, (use) => {
+    const tableData = gristDoc.docData.getTable(use(use(origColumn.table).tableId));
+    return tableData ? use.owner.autoDispose(tableData.tableActionEmitter.addListener(debouncedCountErrors)) : null;
+  });
+
+  // The counts depend on the origColumn and its isRealFormula status, but with the debounced
+  // callback and subscription to data, subscribe to relevant changes manually (rather than using
+  // a Computed).
+  owner.autoDispose(subscribe(use => { use(origColumn.id); use(origColumn.isRealFormula); debouncedCountErrors(); }));
+  return errorMessage;
+}
+
 const cssFieldFormula = styled(buildHighlightedCode, `
   flex: auto;
   cursor: pointer;
@@ -195,3 +246,7 @@ const cssColTieConnectors = styled('div', `
   border-left: none;
   z-index: -1;
 `);
+
+const cssError = styled('div', `
+  color: ${colors.error};
+`);