From 85074f3ac884d74744c80ac0d68f625fd6ebd89c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bogdan-=C8=98tefan=20Neac=C8=99u?= <bogdan@nymtech.net>
Date: Wed, 22 Mar 2023 17:21:20 +0200
Subject: [PATCH] Better error log for lacking credential in db

---
 common/credential-storage/src/coconut.rs | 4 ++--
 common/credential-storage/src/error.rs   | 3 +++
 common/credential-storage/src/lib.rs     | 3 ++-
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/common/credential-storage/src/coconut.rs b/common/credential-storage/src/coconut.rs
index a6cd968c2e..f4b78d8846 100644
--- a/common/credential-storage/src/coconut.rs
+++ b/common/credential-storage/src/coconut.rs
@@ -48,12 +48,12 @@ impl CoconutCredentialManager {
     /// Tries to retrieve one of the stored, unused credentials.
     pub(crate) async fn get_next_coconut_credential(
         &self,
-    ) -> Result<CoconutCredential, sqlx::Error> {
+    ) -> Result<Option<CoconutCredential>, sqlx::Error> {
         sqlx::query_as!(
             CoconutCredential,
             "SELECT * FROM coconut_credentials WHERE NOT consumed"
         )
-        .fetch_one(&self.connection_pool)
+        .fetch_optional(&self.connection_pool)
         .await
     }
 
diff --git a/common/credential-storage/src/error.rs b/common/credential-storage/src/error.rs
index fbd9a347f4..83082e0d6a 100644
--- a/common/credential-storage/src/error.rs
+++ b/common/credential-storage/src/error.rs
@@ -13,4 +13,7 @@ pub enum StorageError {
 
     #[error("Inconsistent data in database")]
     InconsistentData,
+
+    #[error("No unused credential in database. You need to buy at least one")]
+    NoCredential,
 }
diff --git a/common/credential-storage/src/lib.rs b/common/credential-storage/src/lib.rs
index bf3af1b272..202cd952c8 100644
--- a/common/credential-storage/src/lib.rs
+++ b/common/credential-storage/src/lib.rs
@@ -90,7 +90,8 @@ impl Storage for PersistentStorage {
         let credential = self
             .coconut_credential_manager
             .get_next_coconut_credential()
-            .await?;
+            .await?
+            .ok_or(StorageError::NoCredential)?;
 
         Ok(credential)
     }