Correctly paginate PostView when read_only is enabled (#5320)

crates/apub/src/api/list_posts.rs

@@ -67,7 +67,7 @@ pub async fn list_posts(
 
   // parse pagination token
   let page_after = if let Some(pa) = &data.page_cursor {
-    Some(pa.read(&mut context.pool()).await?)
+    Some(pa.read(&mut context.pool(), local_user).await?)
   } else {
     None
   };

crates/db_perf/src/main.rs

@@ -163,7 +163,7 @@ async fn try_main() -> LemmyResult<()> {
     if let Some(post_view) = post_views.into_iter().last() {
       println!("👀 getting pagination cursor data for next page");
       let cursor_data = PaginationCursor::after_post(&post_view)
-        .read(&mut conn.into())
+        .read(&mut conn.into(), None)
         .await?;
       page_after = Some(cursor_data);
     } else {

crates/db_schema/src/impls/post.rs

@@ -4,6 +4,7 @@ use crate::{
   schema::{community, person, post, post_actions},
   source::post::{
     Post,
+    PostActionsCursor,
     PostHide,
     PostHideForm,
     PostInsertForm,
@@ -409,6 +410,28 @@ impl PostHide {
   }
 }
 
+impl PostActionsCursor {
+  pub async fn read(
+    pool: &mut DbPool<'_>,
+    post_id: PostId,
+    person_id: Option<PersonId>,
+  ) -> Result<Self, Error> {
+    let conn = &mut get_conn(pool).await?;
+
+    Ok(if let Some(person_id) = person_id {
+      post_actions::table
+        .find((person_id, post_id))
+        .select(Self::as_select())
+        .first(conn)
+        .await
+        .optional()?
+        .unwrap_or_default()
+    } else {
+      Default::default()
+    })
+  }
+}
+
 #[cfg(test)]
 mod tests {
 

crates/db_schema/src/source/post.rs

@@ -4,6 +4,8 @@ use crate::schema::{post, post_actions};
 use chrono::{DateTime, Utc};
 #[cfg(feature = "full")]
 use diesel::{dsl, expression_methods::NullableExpressionMethods};
+#[cfg(feature = "full")]
+use i_love_jesus::CursorKeysModule;
 use serde::{Deserialize, Serialize};
 use serde_with::skip_serializing_none;
 #[cfg(feature = "full")]
@@ -204,7 +206,7 @@ pub struct PostSavedForm {
   pub saved: DateTime<Utc>,
 }
 
-#[derive(PartialEq, Eq, Debug)]
+#[derive(Clone, PartialEq, Eq, Debug)]
 #[cfg_attr(
   feature = "full",
   derive(Identifiable, Queryable, Selectable, Associations)
@@ -257,3 +259,13 @@ pub struct PostHideForm {
   #[new(value = "Utc::now()")]
   pub hidden: DateTime<Utc>,
 }
+
+#[derive(PartialEq, Debug, Clone, Default)]
+#[cfg_attr(feature = "full", derive(Queryable, Selectable, CursorKeysModule))]
+#[cfg_attr(feature = "full", diesel(table_name = post_actions))]
+#[cfg_attr(feature = "full", diesel(check_for_backend(diesel::pg::Pg)))]
+#[cfg_attr(feature = "full", cursor_keys_module(name = post_actions_keys))]
+/// Sorted timestamps of actions on a post.
+pub struct PostActionsCursor {
+  pub read: Option<DateTime<Utc>>,
+}

crates/db_schema/src/utils.rs

@@ -37,7 +37,7 @@ use diesel_async::{
 };
 use diesel_bind_if_some::BindIfSome;
 use futures_util::{future::BoxFuture, Future, FutureExt};
-use i_love_jesus::CursorKey;
+use i_love_jesus::{CursorKey, PaginatedQueryBuilder};
 use lemmy_utils::{
   error::{LemmyErrorExt, LemmyErrorType, LemmyResult},
   settings::SETTINGS,
@@ -734,6 +734,28 @@ impl<RF, LF> Queries<RF, LF> {
   }
 }
 
+pub fn paginate<Q, C>(
+  query: Q,
+  page_after: Option<C>,
+  page_before_or_equal: Option<C>,
+  page_back: bool,
+) -> PaginatedQueryBuilder<C, Q> {
+  let mut query = PaginatedQueryBuilder::new(query);
+
+  if page_back {
+    query = query
+      .before(page_after)
+      .after_or_equal(page_before_or_equal)
+      .limit_and_offset_from_end();
+  } else {
+    query = query
+      .after(page_after)
+      .before_or_equal(page_before_or_equal);
+  }
+
+  query
+}
+
 #[cfg(test)]
 mod tests {
 

crates/db_views/src/post_view.rs

@@ -14,7 +14,6 @@ use diesel::{
   QueryDsl,
 };
 use diesel_async::RunQueryDsl;
-use i_love_jesus::PaginatedQueryBuilder;
 use lemmy_db_schema::{
   aggregates::structs::{post_aggregates_keys as key, PostAggregates},
   aliases::creator_community_actions,
@@ -38,6 +37,7 @@ use lemmy_db_schema::{
   source::{
     community::{CommunityFollower, CommunityFollowerState},
     local_user::LocalUser,
+    post::{post_actions_keys, PostActionsCursor},
     site::Site,
   },
   utils::{
@@ -49,6 +49,7 @@ use lemmy_db_schema::{
     get_conn,
     limit_and_offset,
     now,
+    paginate,
     Commented,
     DbConn,
     DbPool,
@@ -306,12 +307,6 @@ fn queries<'a>() -> Queries<
       query = query.filter(post_aggregates::comments.eq(0));
     };
 
-    if o.read_only.unwrap_or_default() {
-      query = query
-        .filter(post_actions::read.is_not_null())
-        .then_order_by(post_actions::read.desc())
-    }
-
     if !o.show_read.unwrap_or(o.local_user.show_read_posts()) {
       // Do not hide read posts when it is a user profile view
       // Or, only hide read posts on non-profile views
@@ -370,21 +365,23 @@ fn queries<'a>() -> Queries<
     let (limit, offset) = limit_and_offset(o.page, o.limit)?;
     query = query.limit(limit).offset(offset);
 
-    let mut query = PaginatedQueryBuilder::new(query);
-
-    let page_after = o.page_after.map(|c| c.0);
-    let page_before_or_equal = o.page_before_or_equal.map(|c| c.0);
-
-    if o.page_back.unwrap_or_default() {
-      query = query
-        .before(page_after)
-        .after_or_equal(page_before_or_equal)
-        .limit_and_offset_from_end();
+    let query = if o.read_only.unwrap_or_default() {
+      paginate(
+        query,
+        o.page_after.map(|c| c.post_actions),
+        None,
+        o.page_back.unwrap_or_default(),
+      )
+      .filter(post_actions::read.is_not_null())
+      .then_desc(post_actions_keys::read)
+      .as_query()
     } else {
-      query = query
-        .after(page_after)
-        .before_or_equal(page_before_or_equal);
-    }
+      let mut query = paginate(
+        query,
+        o.page_after.map(|c| c.post_aggregates),
+        o.page_before_or_equal,
+        o.page_back.unwrap_or_default(),
+      );
 
       // featured posts first
       query = if o.community_id.is_none() || o.community_id_just_for_prefetch {
@@ -429,8 +426,8 @@ fn queries<'a>() -> Queries<
       // finally use unique post id as tie breaker
       query = query.then_desc(key::post_id);
 
-    // Not done by debug_query
-    let query = query.as_query();
+      query.as_query()
+    };
 
     debug!("Post View Query: {:?}", debug_query::<Pg, _>(&query));
 
@@ -466,29 +463,36 @@ impl PaginationCursor {
     // hex encoding to prevent ossification
     PaginationCursor(format!("P{:x}", view.counts.post_id.0))
   }
-  pub async fn read(&self, pool: &mut DbPool<'_>) -> Result<PaginationCursorData, Error> {
+  pub async fn read(
+    &self,
+    pool: &mut DbPool<'_>,
+    local_user: Option<&LocalUser>,
+  ) -> Result<PaginationCursorData, Error> {
     let err_msg = || Error::QueryBuilderError("Could not parse pagination token".into());
-    let token = PostAggregates::read(
-      pool,
-      PostId(
+    let post_id = PostId(
       self
         .0
         .get(1..)
         .and_then(|e| i32::from_str_radix(e, 16).ok())
         .ok_or_else(err_msg)?,
-      ),
-    )
-    .await?;
+    );
+    let post_aggregates = PostAggregates::read(pool, post_id).await?;
+    let post_actions = PostActionsCursor::read(pool, post_id, local_user.person_id()).await?;
 
-    Ok(PaginationCursorData(token))
+    Ok(PaginationCursorData {
+      post_aggregates,
+      post_actions,
+    })
   }
 }
 
-// currently we use a postaggregates struct as the pagination token.
-// we only use some of the properties of the post aggregates, depending on which sort type we page
-// by
+// currently we use aggregates or actions as the pagination token.
+// we only use some of the properties, depending on which sort type we page by
 #[derive(Clone)]
-pub struct PaginationCursorData(PostAggregates);
+pub struct PaginationCursorData {
+  post_aggregates: PostAggregates,
+  post_actions: PostActionsCursor,
+}
 
 #[derive(Clone, Default)]
 pub struct PostQuery<'a> {
@@ -509,7 +513,7 @@ pub struct PostQuery<'a> {
   pub page: Option<i64>,
   pub limit: Option<i64>,
   pub page_after: Option<PaginationCursorData>,
-  pub page_before_or_equal: Option<PaginationCursorData>,
+  pub page_before_or_equal: Option<PostAggregates>,
   pub page_back: Option<bool>,
   pub show_hidden: Option<bool>,
   pub show_read: Option<bool>,
@@ -589,7 +593,7 @@ impl<'a> PostQuery<'a> {
       } else {
         v.pop()
       };
-      let limit_cursor = Some(PaginationCursorData(item.expect("else case").counts));
+      let limit_cursor = Some(item.expect("else case").counts);
       Ok(Some(PostQuery {
         page_before_or_equal: limit_cursor,
         ..self.clone()
@@ -1577,7 +1581,10 @@ mod tests {
     let mut page_after = None;
     loop {
       let post_listings = PostQuery {
-        page_after,
+        page_after: page_after.map(|p| PaginationCursorData {
+          post_aggregates: p,
+          post_actions: Default::default(),
+        }),
         ..options.clone()
       }
       .list(&data.site, pool)
@@ -1586,7 +1593,7 @@ mod tests {
       listed_post_ids.extend(post_listings.iter().map(|p| p.post.id));
 
       if let Some(p) = post_listings.into_iter().last() {
-        page_after = Some(PaginationCursorData(p.counts));
+        page_after = Some(p.counts);
       } else {
         break;
       }
@@ -1597,7 +1604,10 @@ mod tests {
     let mut page_before = None;
     loop {
       let post_listings = PostQuery {
-        page_after: page_before,
+        page_after: page_before.map(|p| PaginationCursorData {
+          post_aggregates: p,
+          post_actions: Default::default(),
+        }),
         page_back: Some(true),
         ..options.clone()
       }
@@ -1614,7 +1624,7 @@ mod tests {
       listed_post_ids_forward.truncate(index);
 
       if let Some(p) = post_listings.into_iter().next() {
-        page_before = Some(PaginationCursorData(p.counts));
+        page_before = Some(p.counts);
       } else {
         break;
       }