Optimize database queries in can_view_post()

src/models/posts/helpers.rs

@@ -3,7 +3,8 @@ use uuid::Uuid;
 
 use crate::errors::DatabaseError;
 use crate::models::reactions::queries::find_favourited_by_user;
-use crate::models::relationships::queries::get_relationship;
+use crate::models::relationships::queries::has_relationship;
+use crate::models::relationships::types::RelationshipType;
 use crate::models::users::types::User;
 use super::queries::{get_posts, find_reposted_by_user};
 use super::types::{Post, PostActions, Visibility};
@@ -65,41 +66,41 @@ pub async fn can_view_post(
     user: Option<&User>,
     post: &Post,
 ) -> Result<bool, DatabaseError> {
+    let is_mentioned = |user: &User| {
+        post.mentions.iter().any(|profile| profile.id == user.profile.id)
+    };
     let result = match post.visibility {
         Visibility::Public => true,
         Visibility::Direct => {
             if let Some(user) = user {
                 // Returns true if user is mentioned
-                post.mentions.iter()
+                is_mentioned(user)
-                    .any(|profile| profile.id == user.profile.id)
             } else {
                 false
             }
         },
         Visibility::Followers => {
             if let Some(user) = user {
-                let relationship = get_relationship(
+                let is_following = has_relationship(
                     db_client,
-                    &post.author.id,
                     &user.id,
+                    &post.author.id,
+                    RelationshipType::Follow,
                 ).await?;
-                let is_mentioned = post.mentions.iter()
+                is_following || is_mentioned(user)
-                    .any(|profile| profile.id == user.profile.id);
-                relationship.followed_by || is_mentioned
             } else {
                 false
             }
         },
         Visibility::Subscribers => {
             if let Some(user) = user {
-                let relationship = get_relationship(
+                let is_subscriber = has_relationship(
                     db_client,
-                    &post.author.id,
                     &user.id,
+                    &post.author.id,
+                    RelationshipType::Subscription,
                 ).await?;
-                let is_mentioned = post.mentions.iter()
+                is_subscriber || is_mentioned(user)
-                    .any(|profile| profile.id == user.profile.id);
-                relationship.subscription_from || is_mentioned
             } else {
                 false
             }

src/models/relationships/queries.rs

@@ -87,6 +87,29 @@ pub async fn get_relationship(
     Ok(relationship_map)
 }
 
+pub async fn has_relationship(
+    db_client: &impl GenericClient,
+    source_id: &Uuid,
+    target_id: &Uuid,
+    relationship_type: RelationshipType,
+) -> Result<bool, DatabaseError> {
+    let maybe_row = db_client.query_opt(
+        "
+        SELECT 1
+        FROM relationship
+        WHERE
+            source_id = $1 AND target_id = $2
+            AND relationship_type = $3
+        ",
+        &[
+            &source_id,
+            &target_id,
+            &relationship_type,
+        ],
+    ).await?;
+    Ok(maybe_row.is_some())
+}
+
 pub async fn follow(
     db_client: &mut impl GenericClient,
     source_id: &Uuid,