Always assign default language before checking if language is allowed (fixes #5131)

crates/api_crud/src/comment/create.rs

@@ -89,17 +89,13 @@ pub async fn create_comment(
   }
 
   // attempt to set default language if none was provided
-  let language_id = match data.language_id {
-    Some(lid) => lid,
-    None => {
-      default_post_language(
+  let language_id = default_post_language(
     &mut context.pool(),
+    data.language_id,
     community_id,
     local_user_view.local_user.id,
   )
-      .await?
-    }
-  };
+  .await?;
 
   CommunityLanguage::is_allowed_community_language(&mut context.pool(), language_id, community_id)
     .await?;

crates/api_crud/src/comment/update.rs

@@ -55,14 +55,19 @@ pub async fn update_comment(
     Err(LemmyErrorType::NoCommentEditAllowed)?
   }
 
-  if let Some(language_id) = data.language_id {
+    let language_id = default_post_language(
+      &mut context.pool(),
+      data.language_id,
+      community_id,
+      local_user_view.local_user.id,
+    )
+    .await?;
     CommunityLanguage::is_allowed_community_language(
       &mut context.pool(),
       language_id,
       orig_comment.community.id,
     )
     .await?;
-  }
 
   let slur_regex = local_site_to_slur_regex(&local_site);
   let url_blocklist = get_url_blocklist(&context).await?;

crates/api_crud/src/post/create.rs

@@ -105,17 +105,13 @@ pub async fn create_post(
   }
 
   // attempt to set default language if none was provided
-  let language_id = match data.language_id {
-    Some(lid) => lid,
-    None => {
-      default_post_language(
+  let language_id = default_post_language(
     &mut context.pool(),
+    data.language_id,
     community_id,
     local_user_view.local_user.id,
   )
-      .await?
-    }
-  };
+  .await?;
 
   // Only need to check if language is allowed in case user set it explicitly. When using default
   // language, it already only returns allowed languages.

crates/api_crud/src/post/update.rs

@@ -101,14 +101,19 @@ pub async fn update_post(
     Err(LemmyErrorType::NoPostEditAllowed)?
   }
 
-  if let Some(language_id) = data.language_id {
+    let language_id = default_post_language(
+      &mut context.pool(),
+      data.language_id,
+      community_id,
+      local_user_view.local_user.id,
+    )
+    .await?;
     CommunityLanguage::is_allowed_community_language(
       &mut context.pool(),
       language_id,
       orig_post.community_id,
     )
     .await?;
-  }
 
   // handle changes to scheduled_publish_time
   let scheduled_publish_time = match (

crates/db_schema/src/impls/actor_language.rs

@@ -321,11 +321,14 @@ impl CommunityLanguage {
 
 pub async fn default_post_language(
   pool: &mut DbPool<'_>,
+  language_id: Option<LanguageId>,
   community_id: CommunityId,
   local_user_id: LocalUserId,
 ) -> Result<LanguageId, Error> {
   use crate::schema::{community_language::dsl as cl, local_user_language::dsl as ul};
   let conn = &mut get_conn(pool).await?;
+  match language_id {
+    None | Some(LanguageId(0)) => {
       let mut intersection = ul::local_user_language
         .inner_join(cl::community_language.on(ul::language_id.eq(cl::language_id)))
         .filter(ul::local_user_id.eq(local_user_id))
@@ -343,6 +346,9 @@ pub async fn default_post_language(
         Ok(UNDETERMINED_ID)
       }
     }
+    Some(lid) => Ok(lid),
+  }
+}
 
 /// If no language is given, set all languages
 async fn convert_update_languages(