fix: relation widget performance (#3975)

packages/netlify-cms-lib-widgets/package.json

@@ -18,6 +18,7 @@
   },
   "peerDependencies": {
     "immutable": "^3.7.6",
+    "lodash": "^4.17.11",
     "moment": "^2.24.0"
   }
 }

packages/netlify-cms-lib-widgets/src/__tests__/stringTemplate.spec.js

@@ -4,6 +4,7 @@ import {
   compileStringTemplate,
   parseDateFromEntry,
   extractTemplateVars,
+  expandPath,
 } from '../stringTemplate';
 describe('stringTemplate', () => {
   describe('keyToPathArray', () => {
@@ -107,4 +108,66 @@ describe('stringTemplate', () => {
       ).toBe('SLUG');
     });
   });
+
+  describe('expandPath', () => {
+    it('should expand wildcard paths', () => {
+      const data = {
+        categories: [
+          {
+            name: 'category 1',
+          },
+          {
+            name: 'category 2',
+          },
+        ],
+      };
+
+      expect(expandPath({ data, path: 'categories.*.name' })).toEqual([
+        'categories.0.name',
+        'categories.1.name',
+      ]);
+    });
+
+    it('should handle wildcard at the end of the path', () => {
+      const data = {
+        nested: {
+          otherNested: {
+            list: [
+              {
+                title: 'title 1',
+                nestedList: [{ description: 'description 1' }, { description: 'description 2' }],
+              },
+              {
+                title: 'title 2',
+                nestedList: [{ description: 'description 2' }, { description: 'description 2' }],
+              },
+            ],
+          },
+        },
+      };
+
+      expect(expandPath({ data, path: 'nested.otherNested.list.*.nestedList.*' })).toEqual([
+        'nested.otherNested.list.0.nestedList.0',
+        'nested.otherNested.list.0.nestedList.1',
+        'nested.otherNested.list.1.nestedList.0',
+        'nested.otherNested.list.1.nestedList.1',
+      ]);
+    });
+
+    it('should handle non wildcard index', () => {
+      const data = {
+        categories: [
+          {
+            name: 'category 1',
+          },
+          {
+            name: 'category 2',
+          },
+        ],
+      };
+      const path = 'categories.0.name';
+
+      expect(expandPath({ data, path })).toEqual(['categories.0.name']);
+    });
+  });
 });

packages/netlify-cms-lib-widgets/src/stringTemplate.ts

@@ -1,6 +1,7 @@
 import moment from 'moment';
 import { Map } from 'immutable';
 import { basename, extname } from 'path';
+import { get, trimEnd } from 'lodash';
 
 const FIELD_PREFIX = 'fields.';
 const templateContentPattern = '[^}{]+';
@@ -60,6 +61,41 @@ export const keyToPathArray = (key?: string) => {
   return parts;
 };
 
+export const expandPath = ({
+  data,
+  path,
+  paths = [],
+}: {
+  data: Record<string, unknown>;
+  path: string;
+  paths?: string[];
+}) => {
+  if (path.endsWith('.*')) {
+    path = path + '.';
+  }
+
+  const sep = '.*.';
+  const parts = path.split(sep);
+  if (parts.length === 1) {
+    paths.push(path);
+  } else {
+    const partialPath = parts[0];
+    const value = get(data, partialPath);
+
+    if (Array.isArray(value)) {
+      value.forEach((_, index) => {
+        expandPath({
+          data,
+          path: trimEnd(`${partialPath}.${index}.${parts.slice(1).join(sep)}`, '.'),
+          paths,
+        });
+      });
+    }
+  }
+
+  return paths;
+};
+
 // Allow `fields.` prefix in placeholder to override built in replacements
 // like "slug" and "year" with values from fields of the same name.
 function getExplicitFieldReplacement(key: string, data: Map<string, unknown>) {