From 4594411035d1e2806c91796c76a4f71906003d3a Mon Sep 17 00:00:00 2001
From: Sophia Mersmann <sophia.mersmann1@gmail.com>
Date: Wed, 22 Jan 2025 16:34:47 +0100
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20allow=20single-entity=20selectio?=
 =?UTF-8?q?n=20for=20charts=20split=20by=20metric?=
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---
 ...tiEntitySelectionForChartsSplitByMetric.ts | 48 +++++++++++++++++++
 .../grapher/src/core/Grapher.tsx              | 11 ++---
 2 files changed, 51 insertions(+), 8 deletions(-)
 create mode 100644 db/migration/1737580227406-RetainMultiEntitySelectionForChartsSplitByMetric.ts

diff --git a/db/migration/1737580227406-RetainMultiEntitySelectionForChartsSplitByMetric.ts b/db/migration/1737580227406-RetainMultiEntitySelectionForChartsSplitByMetric.ts
new file mode 100644
index 0000000000..0038e1ed57
--- /dev/null
+++ b/db/migration/1737580227406-RetainMultiEntitySelectionForChartsSplitByMetric.ts
@@ -0,0 +1,48 @@
+import { MigrationInterface, QueryRunner } from "typeorm"
+
+// As part of the migration, we'll update all charts that are split by metric
+// and have a 'change-country' setting to use the 'add-country' setting instead.
+// These charts should be excluded from the migration since the 'change-country'
+// is more appropriate for them.
+const slugs = [
+    "cancer-death-rates-by-age",
+    "neonatal-deaths-by-cause",
+    "dealing-with-anxiety-depression-approaches",
+    "mental-illness-estimated-cases",
+    "deaths-from-cardiovascular-disease-type",
+    "country-level-monthly-temperature-anomalies",
+    "summer-temperature-anomalies",
+    "winter-temperature-anomalies",
+    "autumn-temperature-anomalies",
+    "spring-temperature-anomalies",
+    "5-year-survival-rate-of-cancers-among-female-patients-in-england",
+]
+
+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'
+                AND slug NOT IN (?);
+        `,
+            [slugs]
+        )
+    }
+
+    public async down(): Promise<void> {
+        // no-op
+    }
+}
diff --git a/packages/@ourworldindata/grapher/src/core/Grapher.tsx b/packages/@ourworldindata/grapher/src/core/Grapher.tsx
index 05b5453daa..6c1d75e81f 100644
--- a/packages/@ourworldindata/grapher/src/core/Grapher.tsx
+++ b/packages/@ourworldindata/grapher/src/core/Grapher.tsx
@@ -3692,16 +3692,11 @@ export class Grapher
         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