Prevent user and community with same name

api_tests/src/community.spec.ts

@@ -62,7 +62,7 @@ test("Create community", async () => {
   let prevName = communityRes.community_view.community.name;
   await jestLemmyError(
     () => createCommunity(alpha, prevName),
-    new LemmyError("already_exists", statusBadRequest),
+    new LemmyError("name_already_taken", statusBadRequest),
   );
 
   // Cache the community on beta, make sure it has the other fields
@@ -402,7 +402,7 @@ test("Get community for different casing on domain", async () => {
   let prevName = communityRes.community_view.community.name;
   await jestLemmyError(
     () => createCommunity(alpha, prevName),
-    new LemmyError("already_exists", statusBadRequest),
+    new LemmyError("name_already_taken", statusBadRequest),
   );
 
   // Cache the community on beta, make sure it has the other fields

crates/api/api_crud/src/community/create.rs

@@ -1,3 +1,4 @@
+use crate::check_user_or_community_name_taken;
 use activitypub_federation::{config::Data, http_signatures::generate_actor_keypair};
 use actix_web::web::Json;
 use lemmy_api_utils::{
@@ -82,13 +83,10 @@ pub async fn create_community(
   }
 
   is_valid_actor_name(&data.name)?;
+  check_user_or_community_name_taken(&data.name, &context).await?;
 
   // Double check for duplicate community actor_ids
   let community_ap_id = Community::generate_local_actor_url(&data.name, context.settings())?;
-  let community_dupe = Community::read_from_apub_id(&mut context.pool(), &community_ap_id).await?;
-  if community_dupe.is_some() {
-    Err(LemmyErrorType::AlreadyExists)?
-  }
 
   let keypair = generate_actor_keypair()?;
   let community_form = CommunityInsertForm {

crates/api/api_crud/src/lib.rs

@@ -1,5 +1,9 @@
 use lemmy_api_utils::context::LemmyContext;
-use lemmy_db_schema::source::community::{Community, CommunityActions};
+use lemmy_db_schema::source::{
+  community::{Community, CommunityActions},
+  person::Person,
+};
+use lemmy_utils::error::LemmyResult;
 
 pub mod comment;
 pub mod community;
@@ -22,3 +26,10 @@ async fn community_use_pending(community: &Community, context: &LemmyContext) ->
     .await
     .is_ok()
 }
+
+async fn check_user_or_community_name_taken(name: &str, context: &LemmyContext) -> LemmyResult<()> {
+  // TODO: better to make only a single sql query
+  Person::check_name_taken(&mut context.pool(), name).await?;
+  Community::check_name_taken(&mut context.pool(), name).await?;
+  Ok(())
+}

crates/api/api_crud/src/user/create.rs

@@ -1,3 +1,4 @@
+use crate::check_user_or_community_name_taken;
 use activitypub_federation::{
   config::Data,
   fetch::object_id::ObjectId,
@@ -127,7 +128,7 @@ pub async fn register(
   check_slurs(&data.username, &slur_regex)?;
   check_slurs_opt(&data.answer, &slur_regex)?;
 
-  Person::check_username_taken(pool, &data.username).await?;
+  check_user_or_community_name_taken(&data.username, &context).await?;
 
   if let Some(email) = &data.email {
     LocalUser::check_is_email_taken(pool, email).await?;
@@ -391,7 +392,7 @@ pub async fn authenticate_with_oauth(
             check_slurs(username, &slur_regex)?;
             check_slurs_opt(&tx_data.answer, &slur_regex)?;
 
-            Person::check_username_taken(&mut conn.into(), username).await?;
+            check_user_or_community_name_taken(username, &tx_context).await?;
 
             // We have to create a person, a local_user, and an oauth_account
             let person = create_person(username.clone(), &site_view, &tx_context, conn).await?;

crates/db_schema/src/impls/community.rs

@@ -281,6 +281,18 @@ impl Community {
       .await
       .with_lemmy_type(LemmyErrorType::CouldntUpdate)
   }
+  pub async fn check_name_taken(pool: &mut DbPool<'_>, username: &str) -> LemmyResult<()> {
+    let conn = &mut get_conn(pool).await?;
+    select(not(exists(
+      community::table
+        .filter(lower(community::name).eq(username.to_lowercase()))
+        .filter(community::local.eq(true)),
+    )))
+    .get_result::<bool>(conn)
+    .await?
+    .then_some(())
+    .ok_or(LemmyErrorType::NameAlreadyTaken.into())
+  }
 }
 
 impl CommunityActions {

crates/db_schema/src/impls/person.rs

@@ -140,7 +140,7 @@ impl Person {
       .with_lemmy_type(LemmyErrorType::CouldntUpdate)
   }
 
-  pub async fn check_username_taken(pool: &mut DbPool<'_>, username: &str) -> LemmyResult<()> {
+  pub async fn check_name_taken(pool: &mut DbPool<'_>, username: &str) -> LemmyResult<()> {
     let conn = &mut get_conn(pool).await?;
     select(not(exists(
       person::table
@@ -150,7 +150,7 @@ impl Person {
     .get_result::<bool>(conn)
     .await?
     .then_some(())
-    .ok_or(LemmyErrorType::UsernameAlreadyTaken.into())
+    .ok_or(LemmyErrorType::NameAlreadyTaken.into())
   }
 }
 

crates/utils/src/error.rs

@@ -64,7 +64,7 @@ pub enum LemmyErrorType {
   RegistrationApplicationAnswerRequired,
   RegistrationUsernameRequired,
   EmailAlreadyTaken,
-  UsernameAlreadyTaken,
+  NameAlreadyTaken,
   PersonIsBannedFromCommunity,
   NoIdGiven,
   IncorrectLogin,