Add vault helper hook for the rendering @id. (#210)

src/hooks/useGetVaultEntityId.tsx

@@ -0,0 +1,25 @@
+import { NormalizedEntity } from "@iiif/vault/*";
+import { useViewerState } from "src/context/viewer-context";
+
+declare type ExtendedNormalizedEntity = NormalizedEntity & { id: string };
+
+export default function useGetVaultEntityId(id?: string): string | undefined {
+  const { vault } = useViewerState();
+
+  try {
+    const entity: ExtendedNormalizedEntity | undefined | "" =
+      id && vault.get(id);
+
+    if (!entity) throw new Error(`Vault entity ${id} not found.`);
+
+    /**
+     * Vault seems to handle storage `id` and `@id` differently based on the entity type.
+     * Ex: Manifest level rendering items use `id` while Canvas level rendering items use `@id`.
+     * The following logic returns `@id` if it exists, otherwise falls back to `id`.
+     */
+    return entity?.["@id"] || entity?.id;
+  } catch (error) {
+    console.error(error);
+    return id;
+  }
+}

src/hooks/useViewerDownload.tsx

@@ -1,5 +1,6 @@
 import { RenderingItem } from "src/types/presentation-3";
 import { getLabelAsString } from "src/lib/label-helpers";
+import useGetVaultEntityId from "src/hooks/useGetVaultEntityId";
 import useRendering from "src/hooks/use-iiif/useRendering";
 
 type DownloadItem = {
@@ -12,11 +13,14 @@ function prepareDownloadLinks(
   items: RenderingItem[],
   defaultLabel: string,
 ): DownloadItem[] {
-  return items.map(({ format, id, label }) => ({
-    format,
-    id,
-    label: getLabelAsString(label) || defaultLabel,
-  }));
+  return items.map(({ format, id, label }) => {
+    const resourceId = useGetVaultEntityId(id);
+    return {
+      format,
+      id: resourceId,
+      label: getLabelAsString(label) || defaultLabel,
+    };
+  });
 }
 
 export default function useViewerDownload() {