Merge pull request #12 from readwiseio/tristan/fix-persistent-limit-b…

…uffer-case re-exec a query if items were removed from the persistent results
readwiseio · Dec 5, 2023 · a958b6a · a958b6a
2 parents 249ec1a + 2df803b
commit a958b6a
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Showing 2 changed files with 26 additions and 8 deletions.
diff --git a/src/rx-query.ts b/src/rx-query.ts
@@ -576,14 +576,28 @@ export class RxQueryBase<
             );
 
             for (const changedDoc of changedDocs) {
-              /*
-               * no need to fetch again, we already got the doc from the list of changed docs, and therefore we filter
-               * deleted docs as well
-               */
-              persistedQueryCacheIds.delete(changedDoc[primaryPath] as string);
+              const docWasInOldPersistedResults = persistedQueryCacheIds.has(changedDoc[primaryPath] as string);
+              const docMatchesNow = this.doesDocumentDataMatch(changedDoc);
+
+              if (docWasInOldPersistedResults && !docMatchesNow && this.mangoQuery.limit) {
+                // Unfortunately if any doc was removed from the results since the last result,
+                // there is no way for us to be sure our calculated results are correct.
+                // So we should simply give up and re-exec the query.
+                this._persistentQueryCacheResult = value ?? undefined;
+                this._persistentQueryCacheResultLwt = lwt ?? undefined;
+                return;
+              }
+
+              if (docWasInOldPersistedResults) {
+                /*
+                * no need to fetch again, we already got the doc from the list of changed docs, and therefore we filter
+                * deleted docs as well
+                */
+                persistedQueryCacheIds.delete(changedDoc[primaryPath] as string);
+              }
 
               // ignore deleted docs or docs that do not match the query
-              if (!this.doesDocumentDataMatch(changedDoc)) {
+              if (!docMatchesNow) {
                 continue;
               }
 

diff --git a/test/unit/rx-query.test.ts b/test/unit/rx-query.test.ts
@@ -1831,7 +1831,7 @@ describe('rx-query.test.ts', () => {
             collection.database.destroy();
         });
 
-        it.skip('gives correct limit results when items were removed', async () => {
+        it('gives correct limit results when items were removed', async () => {
             const {collection} = await setUpPersistentQueryCacheCollection();
             const human1 = schemaObjects.human('1', 30);
             const human2 = schemaObjects.human('2', 40);
@@ -1865,10 +1865,14 @@ describe('rx-query.test.ts', () => {
 
             // now when we create the query again, it has no way of knowing how to fill the missing item
             const queryAgain = collection.find({ limit: 2, sort: [{age: 'asc'}], selector: { age: { $gt: 10 } } });
+            assert.strictEqual(queryAgain._execOverDatabaseCount, 0);
+
             await queryAgain.enablePersistentQueryCache(cache);
             const updatedResults = await queryAgain.exec();
-            assert.deepStrictEqual(updatedResults.map(h => h.passportId), ['2', '3']);
 
+            // We must re-exec the query to make it correct.
+            assert.strictEqual(queryAgain._execOverDatabaseCount, 1);
+            assert.deepStrictEqual(updatedResults.map(h => h.passportId), ['2', '3']);
             collection.database.destroy();
         });
     });