Go back to content-driven slice keys in feeds (#2190)

* Go back to deterministic react keys

* Quick fix to cases when custom feeds serve empty responses

src/lib/api/feed-manip.ts

@@ -14,9 +14,15 @@ export type FeedTunerFn = (
 ) => FeedViewPostsSlice[]
 
 export class FeedViewPostsSlice {
+  _reactKey: string
   isFlattenedReply = false
 
-  constructor(public items: FeedViewPost[], public _reactKey: string) {}
+  constructor(public items: FeedViewPost[]) {
+    const item = items[0]
+    this._reactKey = `slice-${item.post.uri}-${
+      item.reason?.indexedAt || item.post.indexedAt
+    }`
+  }
 
   get uri() {
     if (this.isFlattenedReply) {
@@ -120,9 +126,7 @@ export class NoopFeedTuner {
     feed: FeedViewPost[],
     _opts?: {dryRun: boolean; maintainOrder: boolean},
   ): FeedViewPostsSlice[] {
-    return feed.map(
+    return feed.map(item => new FeedViewPostsSlice([item]))
-      item => new FeedViewPostsSlice([item], `slice-${this.keyCounter++}`),
-    )
   }
 }
 
@@ -160,9 +164,7 @@ export class FeedTuner {
     })
 
     if (maintainOrder) {
-      slices = feed.map(
+      slices = feed.map(item => new FeedViewPostsSlice([item]))
-        item => new FeedViewPostsSlice([item], `slice-${this.keyCounter++}`),
-      )
     } else {
       // arrange the posts into thread slices
       for (let i = feed.length - 1; i >= 0; i--) {
@@ -178,9 +180,7 @@ export class FeedTuner {
             continue
           }
         }
-        slices.unshift(
+        slices.unshift(new FeedViewPostsSlice([item]))
-          new FeedViewPostsSlice([item], `slice-${this.keyCounter++}`),
-        )
       }
     }
 

src/lib/api/feed/custom.ts

@@ -37,7 +37,7 @@ export class CustomFeedAPI implements FeedAPI {
         res.data.feed = res.data.feed.slice(0, limit)
       }
       return {
-        cursor: res.data.cursor,
+        cursor: res.data.feed.length ? res.data.cursor : undefined,
         feed: res.data.feed,
       }
     }