fix(extractor): avoid caching results with empty meta, add some self-healing

src/extractor/Extractor.ts

@@ -32,6 +32,7 @@ export abstract class Extractor {
           ...urlResult,
           label: this.formatLabel(urlResult.label ?? this.label),
           ttl: this.ttl,
+
         }),
       );
     } catch (error) {

src/extractor/ExtractorRegistry.test.ts

@@ -49,6 +49,11 @@ describe('ExtractorRegistry', () => {
     expect(urlResults).toMatchSnapshot();
   });
 
+  test('empty results are cached', async () => {
+    const urlResults = await extractorRegistry.handle(ctx, new URL('https://dropload.io/asdfghijklmn.html'), { title: 'title' });
+    expect(urlResults).toMatchSnapshot();
+  });
+
   test('stats returns something', async () => {
     const stats = extractorRegistry.stats();
 

src/extractor/ExtractorRegistry.ts

@@ -79,17 +79,11 @@ export class ExtractorRegistry {
 
     this.logger.info(`Extract ${url} using ${extractor.id} extractor`, ctx);
 
-    const urlResults = await extractor.extract(
-      ctx,
-      normalizedUrl,
-      {
-        ...meta,
-        ...lazyUrlResults[0]?.meta,
-        extractorId: meta?.extractorId ?? extractor.id,
-      },
-    );
+    const mergedMeta: Meta = { ...meta, ...lazyUrlResults[0]?.meta };
+    const urlResults = await extractor.extract(ctx, normalizedUrl, { extractorId: extractor.id, ...mergedMeta });
 
-    if (urlResults.some(urlResult => urlResult.error)) {
+    if (!Object.keys(mergedMeta).length || urlResults.some(urlResult => urlResult.error)) {
+      await this.urlResultCache.delete(cacheKey);
       await this.lazyUrlResultCache.delete(normalizedUrl.href);
 
       return urlResults;

src/extractor/__snapshots__/ExtractorRegistry.test.ts.snap

@@ -1,5 +1,7 @@
 // Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
 
+exports[`ExtractorRegistry empty results are cached 1`] = `[]`;
+
 exports[`ExtractorRegistry returns error result from extractor 1`] = `[]`;
 
 exports[`ExtractorRegistry returns external URLs if enabled by config 1`] = `

src/utils/StreamResolver.ts

@@ -54,7 +54,7 @@ export class StreamResolver {
       try {
         const sourceResults = await source.handle(ctx, type, id);
         const sourceUrlResults = await Promise.all(
-          sourceResults.map(({ url, meta }) => this.extractorRegistry.handle(ctx, url, { ...meta, sourceLabel: source.label, sourceId: source.id, priority: source.priority }, true)),
+          sourceResults.map(({ url, meta }) => this.extractorRegistry.handle(ctx, url, { sourceLabel: source.label, sourceId: source.id, priority: source.priority, ...meta }, true)),
         );
 
         for (const urlResult of sourceUrlResults.flat()) {