(core) Showing censored values as a grey cell

Test Plan: Block read access to column A based on the condition rec.B == 1. Then setting B = 1 in a row makes the cell under A grey.

Reviewers: dsagal

Reviewed By: dsagal

Subscribers: paulfitz, dsagal

Differential Revision: https://phab.getgrist.com/D2828

app/client/components/viewCommon.css

@@ -78,6 +78,27 @@
   background-color: unset;
 }
 
+.field_clip.invalid.field-error-C {
+  background-color: unset;
+  color: var(--grist-color-dark-grey);
+  padding-left: 18px;
+}
+
+.field_clip.invalid.field-error-C::before {
+  /* based on standard icon styles */
+  content: "";
+  position: absolute;
+  top: 4px;
+  left: 2px;
+  width: 14px;
+  height: 14px;
+  background-color: var(--grist-color-dark-grey);
+  -webkit-mask-repeat: no-repeat;
+  -webkit-mask-position: center;
+  -webkit-mask-size: contain;
+  -webkit-mask-image: var(--icon-Lock);
+}
+
 .field_clip.field-error-U {
   color: #6363a2;
   background-color: unset;

app/client/widgets/FieldEditor.ts

@@ -152,7 +152,19 @@ export class FieldEditor extends Disposable {
 
     const column = this._field.column();
     const cellCurrentValue = this._editRow.cells[this._field.colId()].peek();
-    const cellValue = column.isFormula() ? column.formula() : cellCurrentValue;
+    let cellValue: CellValue;
+    if (column.isFormula()) {
+      cellValue = column.formula();
+    } else if (Array.isArray(cellCurrentValue) && cellCurrentValue[0] === 'C') {
+      // This cell value is censored by access control rules
+      // Really the rules should also block editing, but in case they don't, show a blank value
+      // rather than a 'C'. However if the user tries to edit the cell and then clicks away
+      // without typing anything the empty string is saved, deleting what was there.
+      // We should probably just automatically block updates where reading is not allowed.
+      cellValue = '';
+    } else {
+      cellValue = cellCurrentValue;
+    }
 
     // Enter formula-editing mode (e.g. click-on-column inserts its ID) only if we are opening the
     // editor by typing into it (and overriding previous formula). In other cases (e.g. double-click),

app/plugin/objtypes.ts

@@ -109,6 +109,19 @@ export class SkipValue {
   }
 }
 
+/**
+ * A placeholder for a value hidden by access control rules.
+ * Depending on the types of the columns involved, copying
+ * a censored value and pasting elsewhere will either use
+ * CensoredValue.__repr__ (python) or CensoredValue.toString (typescript)
+ * so they should match
+ */
+export class CensoredValue {
+  public toString() {
+    return 'CENSORED';
+  }
+}
+
 /**
  * Produces a Grist-encoded version of the value, e.g. turning a Date into ['d', timestamp].
  * Returns ['U', repr(value)] if it fails to encode otherwise.
@@ -135,6 +148,8 @@ export function encodeObject(value: unknown): CellValue {
         // TODO Depending on how it's used, may want to return ['d', timestamp] for UTC midnight.
         return ['D', timestamp, 'UTC'];
       }
+    } else if (value instanceof CensoredValue) {
+      return ['C'];
     } else if (value instanceof RaisedException) {
       return ['E', value.name, value.message, value.details];
     } else if (Array.isArray(value)) {
@@ -172,6 +187,7 @@ export function decodeObject(value: CellValue): unknown {
       case 'P': return new PendingValue();
       case 'R': return new Reference(String(args[0]), args[1]);
       case 'S': return new SkipValue();
+      case 'C': return new CensoredValue();
       case 'U': return new UnknownValue(args[0]);
     }
   } catch (e) {

app/server/lib/GranularAccess.ts

@@ -888,9 +888,9 @@ export class GranularAccess implements GranularAccessForBundle {
     if (colValues === undefined) {
       censorAt = () => 1;
     } else if (Array.isArray(action[2])) {
-      censorAt = (colId, idx) => (colValues as BulkColValues)[colId][idx] = 'CENSORED';  // TODO Pick a suitable value
+      censorAt = (colId, idx) => (colValues as BulkColValues)[colId][idx] = ['C'];  // censored
     } else {
-      censorAt = (colId) => (colValues as ColValues)[colId] = 'CENSORED';  // TODO Pick a suitable value
+      censorAt = (colId) => (colValues as ColValues)[colId] = ['C'];  // censored
     }
 
     // These map an index of a row in the action to its index in rowsBefore and in rowsAfter.

sandbox/grist/objtypes.py

@@ -105,6 +105,17 @@ class UnmarshallableValue(object):
 # document was just migrated.
 _pending_sentinel = object()
 
+# A placeholder for a value hidden by access control rules.
+# Depending on the types of the columns involved, copying
+# a censored value and pasting elsewhere will either use
+# CensoredValue.__repr__ (python) or CensoredValue.toString (typescript)
+# so they should match
+class CensoredValue(object):
+  def __repr__(self):
+    return 'CENSORED'
+
+_censored_sentinel = CensoredValue()
+
 
 _max_js_int = 1<<31
 
@@ -178,6 +189,8 @@ def encode_object(value):
       return ['O', {key: encode_object(val) for key, val in value.iteritems()}]
     elif value == _pending_sentinel:
       return ['P']
+    elif value == _censored_sentinel:
+      return ['C']
     elif isinstance(value, UnmarshallableValue):
       return ['U', value.value_repr]
   except Exception as e:
@@ -218,6 +231,8 @@ def decode_object(value):
       return {decode_object(key): decode_object(val) for key, val in args[0].iteritems()}
     elif code == 'P':
       return _pending_sentinel
+    elif code == 'C':
+      return _censored_sentinel
     elif code == 'U':
       return UnmarshallableValue(args[0])
     raise KeyError("Unknown object type code %r" % code)