chore: simplifying the code a bit by just using lodash under the hood for the pick method

Signed-off-by: blam <ben@blam.sh>

.changeset/tough-cameras-beam.md

@@ -7,4 +7,4 @@ Provide some more default filters out of the box and refactoring how the filters
 - `parseEntityRef` will take an string entity triplet and return a parsed object.
 - `pick` will allow you to reference a specific property in the piped object.
 
-So you can now combine things like this: `${{ parameters.entity | parseEntityRef | pick('name') }}` to get the name of a specific entity, or `${{ parameters.repoUrl | parseRepoUrl | pick('owner) }}` to get the owner of a repo.
+So you can now combine things like this: `${{ parameters.entity | parseEntityRef | pick('name') }}` to get the name of a specific entity, or `${{ parameters.repoUrl | parseRepoUrl | pick('owner') }}` to get the owner of a repo.

plugins/scaffolder-backend/src/lib/templating/filters.ts

@@ -18,6 +18,7 @@ import { ScmIntegrations } from '@backstage/integration';
 import { JsonValue } from '@backstage/types';
 import { TemplateFilter } from '..';
 import { parseRepoUrl } from '../../scaffolder/actions/builtin/publish/util';
+import get from 'lodash/get';
 
 export const createDefaultFilters = ({
   integrations,
@@ -27,19 +28,7 @@ export const createDefaultFilters = ({
   return {
     parseRepoUrl: url => parseRepoUrl(url as string, integrations),
     parseEntityRef: ref => parseEntityRef(ref as string),
-    pick: (obj: JsonValue, key: JsonValue) => {
-      if (
-        typeof obj === 'object' &&
-        !Array.isArray(obj) &&
-        typeof key === 'string'
-      ) {
-        return obj?.[key];
-      }
-
-      throw new Error(
-        `Invalid arguments to pick filter, expected object and string, got ${typeof obj} and ${typeof key}`,
-      );
-    },
+    pick: (obj: JsonValue, key: JsonValue) => get(obj, key as string),
     projectSlug: repoUrl => {
       const { owner, repo } = parseRepoUrl(repoUrl as string, integrations);
       return `${owner}/${repo}`;

plugins/scaffolder-backend/src/scaffolder/actions/builtin/fetch/template.ts

@@ -50,10 +50,7 @@ export function createFetchTemplateAction(options: {
     additionalTemplateGlobals,
   } = options;
 
-  const templateFilters = {
-    ...createDefaultFilters({ integrations }),
-    ...additionalTemplateFilters,
-  };
+  const defaultTemplateFilters = createDefaultFilters({ integrations });
 
   return createTemplateAction<{
     url: string;
@@ -237,7 +234,10 @@ export function createFetchTemplateAction(options: {
 
       const renderTemplate = await SecureTemplater.loadRenderer({
         cookiecutterCompat: ctx.input.cookiecutterCompat,
-        templateFilters,
+        templateFilters: {
+          ...defaultTemplateFilters,
+          ...additionalTemplateFilters,
+        },
         templateGlobals: additionalTemplateGlobals,
       });
 

plugins/scaffolder-backend/src/scaffolder/tasks/NunjucksWorkflowRunner.test.ts

@@ -750,6 +750,36 @@ describe('DefaultWorkflowRunner', () => {
 
       expect(output.foo).toEqual('component');
     });
+
+    it('should allow deep nesting of picked objects', async () => {
+      const task = createMockTaskWithSpec({
+        apiVersion: 'scaffolder.backstage.io/v1beta3',
+        steps: [
+          {
+            id: 'test',
+            name: 'name',
+            action: 'output-action',
+            input: {},
+          },
+        ],
+        output: {
+          foo: '${{ parameters.entity | pick("something.deeply.nested") }}',
+        },
+        parameters: {
+          entity: {
+            something: {
+              deeply: {
+                nested: 'component',
+              },
+            },
+          },
+        },
+      });
+
+      const { output } = await runner.execute(task);
+
+      expect(output.foo).toEqual('component');
+    });
   });
 
   describe('dry run', () => {