Make composite able to have custom handler for missing parent ids

This will be useful next for application menu items, where a missing parent id cannot be fatal.

Co-authored-by: Janne Savolainen <janne.savolainen@live.fi>

Signed-off-by: Iku-turso <mikko.aspiala@gmail.com>

src/features/application-menu/main/menu-items/get-composite/get-composite.test.ts

@@ -4,6 +4,7 @@
  */
 
 import { sortBy } from "lodash/fp";
+import type { Composite } from "./get-composite";
 import getComposite from "./get-composite";
 import { getCompositePaths } from "./get-composite-paths/get-composite-paths";
 
@@ -165,7 +166,7 @@ describe("get-composite", () => {
     );
   });
 
-  it("given missing parent ids, throws", () => {
+  it("given items with missing parent ids, when creating composite without handling for unknown parents, throws", () => {
     const someItem = {
       someId: "some-id",
       someParentId: undefined,
@@ -186,10 +187,54 @@ describe("get-composite", () => {
         getParentId: (x) => x.someParentId,
       });
     }).toThrow(
-      'Tried to get a composite but encountered missing parent ids: "some-missing-id"',
+      `Tried to get a composite but encountered missing parent ids: "some-missing-id".
+
+Available parent ids are:
+"some-id",
+"some-other-id"`,
     );
   });
 
+  describe("given items with missing parent ids, when creating composite with handling for missing parents", () => {
+    let composite: Composite<any>;
+    let handleMissingParentIdMock: jest.Mock;
+
+    beforeEach(() => {
+      const someItem = {
+        id: "some-root-id",
+        parentId: undefined,
+      };
+
+      const someItemWithMissingParentId = {
+        id: "some-orphan-id",
+        // Note: missing parent id makes the item orphan.
+        parentId: "some-missing-id",
+      };
+
+      const items = [someItem, someItemWithMissingParentId];
+
+      handleMissingParentIdMock = jest.fn();
+
+      composite = getComposite({
+        source: items,
+        handleMissingParentIds: handleMissingParentIdMock,
+      });
+    });
+
+    it("creates composite without the orphan item, and without throwing", () => {
+      const paths = getCompositePaths(composite);
+
+      expect(paths).toEqual(["some-root-id"]);
+    });
+
+    it("handles the missing parent ids", () => {
+      expect(handleMissingParentIdMock).toHaveBeenCalledWith({
+        missingParentIds: ["some-missing-id"],
+        availableParentIds: ["some-root-id", "some-orphan-id"],
+      });
+    });
+  });
+
   it("given undefined ids, throws", () => {
     const root = {
       someParentId: undefined,

src/features/application-menu/main/menu-items/get-composite/get-composite.ts

@@ -30,12 +30,14 @@ export default <T>({
   getId = get("id"),
   getParentId = get("parentId"),
   getOrderedChildren = (things: T[]) => sortBy("orderNumber", things),
+  handleMissingParentIds = throwMissingParentIds,
 }: {
   source: T[];
   rootId?: string;
   getId?: (thing: T) => string;
   getParentId?: (thing: T) => string | undefined;
   getOrderedChildren?: (things: T[]) => T[];
+  handleMissingParentIds?: (parentIdsForHandling: ParentIdsForHandling) => void;
 }) => {
   const undefinedIds = pipeline(
     source,
@@ -68,14 +70,10 @@ export default <T>({
 
   const allParentIds = pipeline(source, map(getParentId), uniq, compact);
 
-  const unknownParentIds = without(allIds, allParentIds);
+  const missingParentIds = without(allIds, allParentIds);
 
-  if (unknownParentIds.length) {
-    throw new Error(
-      `Tried to get a composite but encountered missing parent ids: "${unknownParentIds
-        .map((x) => String(x))
-        .join('", "')}"`,
-    );
+  if (missingParentIds.length) {
+    handleMissingParentIds({ missingParentIds, availableParentIds: allIds });
   }
 
   const toComposite = (thing: T): Composite<T> => {
@@ -118,3 +116,19 @@ export default <T>({
 
   return toComposite(roots[0]);
 };
+
+interface ParentIdsForHandling {
+  missingParentIds: string[];
+  availableParentIds: string[];
+}
+
+const throwMissingParentIds = ({
+  missingParentIds,
+  availableParentIds,
+}: ParentIdsForHandling) => {
+  throw new Error(
+    `Tried to get a composite but encountered missing parent ids: "${missingParentIds.join(
+      '", "',
+    )}".\n\nAvailable parent ids are:\n"${availableParentIds.join('",\n"')}"`,
+  );
+};