Merge pull request weiran#222 from JeffreyCA/master

Fix duplicates in feed and next page fetching for "New" and "Jobs" posts
muizidn · Dec 5, 2021 · 2247ff7 · 2247ff7
2 parents 9654c16 + 5089154
commit 2247ff7
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Showing 2 changed files with 23 additions and 7 deletions.
diff --git a/App/Feed/FeedViewModel.swift b/App/Feed/FeedViewModel.swift
@@ -11,8 +11,10 @@ import PromiseKit
 
 class FeedViewModel {
     var posts: [Post] = []
+    var postIds: Set<Int> = Set()
     var postType: PostType = .news
     var pageIndex = 1
+    var lastPostId = 0
     var isFetching = false
 
     func fetchFeed(fetchNextPage: Bool = false) -> Promise<Void> {
@@ -21,22 +23,31 @@ class FeedViewModel {
         }
 
         if fetchNextPage {
-            pageIndex += 1
+            if postType == .newest || postType == .jobs {
+                lastPostId = posts.last?.id ?? lastPostId
+            } else {
+                pageIndex += 1
+            }
         }
 
         isFetching = true
 
         return firstly {
-            HackersKit.shared.getPosts(type: postType, page: pageIndex)
+            HackersKit.shared.getPosts(type: postType, page: pageIndex, nextId: lastPostId)
         }.done { posts in
-            self.posts.append(contentsOf: posts)
+            let newPosts = posts.filter { !self.postIds.contains($0.id) }
+            let newPostIds = newPosts.map { $0.id }
+            self.posts.append(contentsOf: newPosts)
+            self.postIds.formUnion(newPostIds)
             self.isFetching = false
         }
     }
 
     func reset() {
         posts = []
+        postIds = Set()
         pageIndex = 1
+        lastPostId = 0
         isFetching = false
     }
 

diff --git a/Shared Frameworks/HackersKit/HackersKit+PostsList.swift b/Shared Frameworks/HackersKit/HackersKit+PostsList.swift
@@ -11,18 +11,23 @@ import PromiseKit
 import SwiftSoup
 
 extension HackersKit {
-    func getPosts(type: PostType, page: Int = 1) -> Promise<[Post]> {
+    func getPosts(type: PostType, page: Int = 1, nextId: Int = 0) -> Promise<[Post]> {
         firstly {
-            fetchPostsHtml(type: type, page: page)
+            fetchPostsHtml(type: type, page: page, nextId: nextId)
         }.map { html in
             try HtmlParser.postsTableElement(from: html)
         }.compactMap { tableElement in
             try HtmlParser.posts(from: tableElement, type: type)
         }
     }
 
-    private func fetchPostsHtml(type: PostType, page: Int) -> Promise<String> {
-        let url = URL(string: "https://news.ycombinator.com/\(type.rawValue)?p=\(page)")!
+    private func fetchPostsHtml(type: PostType, page: Int, nextId: Int) -> Promise<String> {
+        var url: URL
+        if type == .newest || type == .jobs {
+            url = URL(string: "https://news.ycombinator.com/\(type.rawValue)?next=\(nextId)")!
+        } else {
+            url = URL(string: "https://news.ycombinator.com/\(type.rawValue)?p=\(page)")!
+        }
         return fetchHtml(url: url)
     }
 }