From d562b43025ce4c354e87f6b0ed60a09ec594e9a7 Mon Sep 17 00:00:00 2001
From: Youngtaek Yoon <noreply@yoon.anonaddy.me>
Date: Fri, 7 Apr 2023 18:23:39 +0900
Subject: [PATCH] fix: return nil where the parent not exists in x/collection
 Query/Parent (#955)

* Do not return error where parent not exists

* Update proto doc

* Add the test

* Update CHANGELOG.md
---
 CHANGELOG.md                           |  1 +
 docs/core/proto-docs.md                |  2 +-
 proto/lbm/collection/v1/query.proto    |  1 -
 x/collection/keeper/grpc_query.go      |  2 +-
 x/collection/keeper/grpc_query_test.go | 14 +++++++++-----
 x/collection/query.pb.go               |  1 -
 6 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 68665a7f5b..8e92859661 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -53,6 +53,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (x/foundation) [\#947](https://github.com/line/lbm-sdk/pull/947) Unpack proposals in x/foundation import-genesis
 * (x/collection) [\#953](https://github.com/line/lbm-sdk/pull/953) Allow zero amount of coin in x/collection Query/Balance
 * (x/collection) [\#954](https://github.com/line/lbm-sdk/pull/954) Remove duplicated events in x/collection Msg/Modify
+* (x/collection) [\#955](https://github.com/line/lbm-sdk/pull/955) Return nil where the parent not exists in x/collection Query/Parent
 
 ### Removed
 
diff --git a/docs/core/proto-docs.md b/docs/core/proto-docs.md
index 98d40bbae0..27f22b95d7 100644
--- a/docs/core/proto-docs.md
+++ b/docs/core/proto-docs.md
@@ -10461,7 +10461,7 @@ QueryParentResponse is the response type for the Query/Parent RPC method.
 
 | Field | Type | Label | Description |
 | ----- | ---- | ----- | ----------- |
-| `parent` | [NFT](#lbm.collection.v1.NFT) |  | parent is the information of the parent token. if there is no parent for the token, it would return nil. |
+| `parent` | [NFT](#lbm.collection.v1.NFT) |  | parent is the information of the parent token. |
 
 
 
diff --git a/proto/lbm/collection/v1/query.proto b/proto/lbm/collection/v1/query.proto
index d9e96202e8..9f97a1c2f7 100644
--- a/proto/lbm/collection/v1/query.proto
+++ b/proto/lbm/collection/v1/query.proto
@@ -310,7 +310,6 @@ message QueryParentRequest {
 // QueryParentResponse is the response type for the Query/Parent RPC method.
 message QueryParentResponse {
   // parent is the information of the parent token.
-  // if there is no parent for the token, it would return nil.
   NFT parent = 1 [(gogoproto.nullable) = false];
 }
 
diff --git a/x/collection/keeper/grpc_query.go b/x/collection/keeper/grpc_query.go
index ec308776c5..c5132ff934 100644
--- a/x/collection/keeper/grpc_query.go
+++ b/x/collection/keeper/grpc_query.go
@@ -430,7 +430,7 @@ func (s queryServer) Parent(c context.Context, req *collection.QueryParentReques
 
 	parent, err := s.keeper.GetParent(ctx, req.ContractId, req.TokenId)
 	if err != nil {
-		return nil, err
+		return nil, nil
 	}
 
 	token, err := s.keeper.GetNFT(ctx, req.ContractId, *parent)
diff --git a/x/collection/keeper/grpc_query_test.go b/x/collection/keeper/grpc_query_test.go
index 363abafa77..8ce4b0381d 100644
--- a/x/collection/keeper/grpc_query_test.go
+++ b/x/collection/keeper/grpc_query_test.go
@@ -720,9 +720,18 @@ func (s *KeeperTestSuite) TestQueryParent() {
 			tokenID:    tokenID,
 			valid:      true,
 			postTest: func(res *collection.QueryParentResponse) {
+				s.Require().NotNil(res)
 				s.Require().Equal(collection.NewNFTID(s.nftClassID, 1), res.Parent.TokenId)
 			},
 		},
+		"valid request with no parent": {
+			contractID: s.contractID,
+			tokenID:    collection.NewNFTID(s.nftClassID, 1),
+			valid:      true,
+			postTest: func(res *collection.QueryParentResponse) {
+				s.Require().Nil(res)
+			},
+		},
 		"invalid contract id": {
 			tokenID: tokenID,
 		},
@@ -733,10 +742,6 @@ func (s *KeeperTestSuite) TestQueryParent() {
 			contractID: s.contractID,
 			tokenID:    collection.NewNFTID("deadbeef", 1),
 		},
-		"no parent": {
-			contractID: s.contractID,
-			tokenID:    collection.NewNFTID(s.nftClassID, 1),
-		},
 	}
 
 	for name, tc := range testCases {
@@ -751,7 +756,6 @@ func (s *KeeperTestSuite) TestQueryParent() {
 				return
 			}
 			s.Require().NoError(err)
-			s.Require().NotNil(res)
 			tc.postTest(res)
 		})
 	}
diff --git a/x/collection/query.pb.go b/x/collection/query.pb.go
index 5a77c86ede..5f1e89a24e 100644
--- a/x/collection/query.pb.go
+++ b/x/collection/query.pb.go
@@ -1388,7 +1388,6 @@ func (m *QueryParentRequest) GetTokenId() string {
 // QueryParentResponse is the response type for the Query/Parent RPC method.
 type QueryParentResponse struct {
 	// parent is the information of the parent token.
-	// if there is no parent for the token, it would return nil.
 	Parent NFT `protobuf:"bytes,1,opt,name=parent,proto3" json:"parent"`
 }