From 28d1ddf7e353a84ffddaa0d05e7aa4b40c54d9e7 Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Thu, 28 Jan 2021 10:09:21 +0100
Subject: [PATCH] Repo: use Option to signal retrieval success or failure

---
 ipfs/repo.nim           | 9 +++++++--
 tests/ipfs/testRepo.nim | 5 ++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/ipfs/repo.nim b/ipfs/repo.nim
index c82f87c8..eaefaeb2 100644
--- a/ipfs/repo.nim
+++ b/ipfs/repo.nim
@@ -1,8 +1,10 @@
+import std/options
 import std/tables
 import std/hashes
 import pkg/libp2p
 import ./ipfsobject
 
+export options
 export ipfsobject
 
 type
@@ -18,5 +20,8 @@ proc store*(repo: Repo, obj: IpfsObject) =
 proc contains*(repo: Repo, id: Cid): bool =
   repo.storage.hasKey(id)
 
-proc retrieve*(repo: Repo, id: Cid): IpfsObject =
-  repo.storage[id]
+proc retrieve*(repo: Repo, id: Cid): Option[IpfsObject] =
+  if repo.contains(id):
+    repo.storage[id].some
+  else:
+    IpfsObject.none
diff --git a/tests/ipfs/testRepo.nim b/tests/ipfs/testRepo.nim
index b54f5cef..a70f2962 100644
--- a/tests/ipfs/testRepo.nim
+++ b/tests/ipfs/testRepo.nim
@@ -14,7 +14,10 @@ suite "repo":
 
   test "retrieves IPFS objects by their content id":
     repo.store(obj)
-    check repo.retrieve(obj.cid) == obj
+    check repo.retrieve(obj.cid).get() == obj
+
+  test "signals retrieval failure":
+    check repo.retrieve(obj.cid).isNone
 
   test "knows which content ids are stored":
     check repo.contains(obj.cid) == false