🐛 allow single-entity selection for charts split by metric

db/migration/1737580227406-RetainMultiEntitySelectionForChartsSplitByMetric.ts

@@ -0,0 +1,23 @@
+import { MigrationInterface, QueryRunner } from "typeorm"
+
+export class RetainMultiEntitySelectionForChartsSplitByMetric1737580227406
+    implements MigrationInterface
+{
+    public async up(queryRunner: QueryRunner): Promise<void> {
+        // Charts faceted by metric used to ignore the 'change-country' setting
+        // and offer multi-entity selection always. The code change that comes
+        // with this migration makes it so that the 'change-country' setting
+        // is respected. This migration updates all existing charts that relied
+        // on the old behavior to use the 'add-country' setting explicitly.
+        await queryRunner.query(`
+            UPDATE chart_configs
+            SET
+                patch = JSON_SET(patch, '$.addCountryMode', 'add-country'),
+                full = JSON_SET(full, '$.addCountryMode', 'add-country')
+            WHERE full ->> '$.addCountryMode' = 'change-country'
+                AND full ->> '$.selectedFacetStrategy' = 'metric';
+        `)
+    }
+
+    public async down(): Promise<void> {}
+}

packages/@ourworldindata/grapher/src/core/Grapher.tsx

@@ -3689,19 +3689,15 @@ export class Grapher
 
     @computed get canSelectMultipleEntities(): boolean {
         if (this.numSelectableEntityNames < 2) return false
+        if (this.selection.numSelectedEntities > 1) return true
         if (this.addCountryMode === EntitySelectionMode.MultipleEntities)
             return true
 
+        // if the chart is currently faceted by entity, then use multi-entity
+        // selection, even if the author specified single-entity-selection
         if (
-            // we force multi-entity selection mode when the chart is faceted
             this.addCountryMode === EntitySelectionMode.SingleEntity &&
-            this.facetStrategy !== FacetStrategy.none &&
-            // unless the author explicitly configured the chart to be split
-            // by metric and hid the facet control
-            !(
-                this.facetStrategy === FacetStrategy.metric &&
-                this.hideFacetControl
-            )
+            this.facetStrategy === FacetStrategy.entity
         )
             return true