Add pagination to feed with Load more button using HTMX

src/main/java/com/discdrop/db/DatabaseService.java

@@ -211,9 +211,11 @@ public class DatabaseService {
         }
     }
 
-    public List<Record.ReleaseGroup> getFeed(List<String> artistMbids, List<String> primaryTypes) {
+    public record FeedResult(List<Record.ReleaseGroup> entries, boolean hasMore) {}
+
+    public FeedResult getFeed(List<String> artistMbids, List<String> primaryTypes, int limit, int offset) {
         var groups = new ArrayList<Record.ReleaseGroup>();
-        if (artistMbids.isEmpty()) return groups;
+        if (artistMbids.isEmpty()) return new FeedResult(groups, false);
 
         var placeholders = String.join(",", artistMbids.stream().map(m -> "?").toList());
         var sql = "SELECT * FROM release_group_cache WHERE artist_mbid IN (" + placeholders + ")";
@@ -222,12 +224,15 @@ public class DatabaseService {
             sql += " AND primary_type IN (" + typePlaceholders + ")";
         }
         sql += " ORDER BY (CASE WHEN first_release_date IS NULL OR first_release_date = '' THEN 1 ELSE 0 END), first_release_date DESC";
+        sql += " LIMIT ? OFFSET ?";
 
         try (Connection conn = getConnection();
              PreparedStatement ps = conn.prepareStatement(sql)) {
             int idx = 1;
             for (var mbid : artistMbids) ps.setString(idx++, mbid);
             for (var type : primaryTypes) ps.setString(idx++, type);
+            ps.setInt(idx++, limit + 1);
+            ps.setInt(idx, offset);
             try (ResultSet rs = ps.executeQuery()) {
                 while (rs.next()) {
                     groups.add(mapReleaseGroup(rs));
@@ -236,7 +241,9 @@ public class DatabaseService {
         } catch (SQLException e) {
             throw new RuntimeException(e);
         }
-        return groups;
+        boolean hasMore = groups.size() > limit;
+        if (hasMore) groups.remove(groups.size() - 1);
+        return new FeedResult(groups, hasMore);
     }
 
     public void deleteReleaseGroupsForArtist(String mbid) {

src/main/java/com/discdrop/service/FeedService.java

@@ -1,6 +1,7 @@
 package com.discdrop.service;
 
 import com.discdrop.db.DatabaseService;
+import com.discdrop.db.DatabaseService.FeedResult;
 import com.discdrop.db.Record.ReleaseGroup;
 import com.discdrop.db.Record.TrackedArtist;
 import jakarta.enterprise.context.ApplicationScoped;
@@ -23,9 +24,15 @@ public class FeedService {
     @Inject
     DatabaseService db;
 
+    public static final int PAGE_SIZE = 20;
+
     public List<ReleaseGroup> getFeedEntries() {
+        return getFeedEntries(1).entries();
+    }
+
+    public FeedResult getFeedEntries(int page) {
         var artists = artistService.findAll();
-        if (artists.isEmpty()) return List.of();
+        if (artists.isEmpty()) return new FeedResult(List.of(), false);
 
         var artistMbids = new ArrayList<String>();
         for (var a : artists) {
@@ -42,7 +49,7 @@ public class FeedService {
             monitoredTypes.addAll(getMonitoredTypes(a));
         }
 
-        return db.getFeed(artistMbids, monitoredTypes.isEmpty() ? allTypes : monitoredTypes);
+        return db.getFeed(artistMbids, monitoredTypes.isEmpty() ? allTypes : monitoredTypes, PAGE_SIZE, (page - 1) * PAGE_SIZE);
     }
 
     private List<String> getMonitoredTypes(TrackedArtist a) {

src/main/java/com/discdrop/web/ArtistController.java

@@ -1,5 +1,6 @@
 package com.discdrop.web;
 
+import com.discdrop.db.DatabaseService.FeedResult;
 import com.discdrop.db.Record.MonitoringFlags;
 import com.discdrop.db.Record.TrackedArtist;
 import com.discdrop.service.ArtistService;
@@ -106,9 +107,12 @@ public class ArtistController {
     @GET
     @Path("/feed-table")
     @Produces(MediaType.TEXT_HTML)
-    public TemplateInstance feedTable() {
-        var entries = feedService.getFeedEntries();
-        return feedEntriesTemplate.data("entries", entries);
+    public TemplateInstance feedTable(@QueryParam("page") @DefaultValue("1") int page) {
+        var result = feedService.getFeedEntries(page);
+        return feedEntriesTemplate
+            .data("entries", result.entries())
+            .data("hasMore", result.hasMore())
+            .data("nextPage", page + 1);
     }
 
     private List<String> getMonitoredTypes(TrackedArtist a) {

src/main/resources/templates/fragments/feed-entries.html

@@ -4,7 +4,6 @@
   <p class="text-sm text-base-content/40 mt-2">Add artists to your collection to see their releases here</p>
 </div>
 {#else}
-<div style="display:flex;flex-direction:column;gap:2.5rem">
 {#for entry in entries}
 <a href="https://musicbrainz.org/release-group/{entry.mbid}" target="_blank" rel="noopener noreferrer"
    class="card card-side bg-base-200 border border-base-300 hover:bg-base-300 card-shadow overflow-hidden">
@@ -36,5 +35,12 @@
   </div>
 </a>
 {/for}
+{#if hasMore}
+<div style="display:flex;justify-content:center;padding:1rem 0">
+  <button class="btn btn-primary btn-sm"
+          hx-get="/api/artists/feed-table?page={nextPage}"
+          hx-target="closest div"
+          hx-swap="outerHTML">Load more</button>
 </div>
 {/if}
+{/if}

src/main/resources/templates/releases.html

@@ -17,7 +17,7 @@
       </a>
     </div>
   </div>
-  <div id="feed-entries" hx-get="/api/artists/feed-table" hx-trigger="load">
+  <div id="feed-entries" hx-get="/api/artists/feed-table" hx-trigger="load" style="display:flex;flex-direction:column;gap:2.5rem">
     <div style="display:flex;justify-content:center;padding:4rem 0">
       <span class="loading loading-spinner loading-lg"></span>
     </div>