From c55b1fa7e4548bc579decd84752bade76c6a30f7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thorben=20G=C3=BCnther?= <admin@xenrox.net>
Date: Mon, 8 Nov 2021 11:29:37 +0100
Subject: [PATCH] Add custom error handling

Will enable clients to better handle different errors.
---
 database/error.go         | 20 ++++++++++++++++++++
 graph/schema.resolvers.go |  2 +-
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 database/error.go

diff --git a/database/error.go b/database/error.go
new file mode 100644
index 0000000..a8a6360
--- /dev/null
+++ b/database/error.go
@@ -0,0 +1,20 @@
+package database
+
+import (
+	"errors"
+
+	"github.com/lib/pq"
+)
+
+// CheckErrorCode returns - depending on the postgres error code - a custom error
+// that can be easier parsed and handled
+func CheckErrorCode(err error) error {
+	// https://www.postgresql.org/docs/current/errcodes-appendix.html
+	if err, ok := err.(*pq.Error); ok {
+		// duplicate key value violates unique constraint: 23505 unique_violation
+		if err.Code == "23505" {
+			return errors.New("NotUnique")
+		}
+	}
+	return err
+}
diff --git a/graph/schema.resolvers.go b/graph/schema.resolvers.go
index 067f761..cbf4fb9 100644
--- a/graph/schema.resolvers.go
+++ b/graph/schema.resolvers.go
@@ -61,7 +61,7 @@ func (r *mutationResolver) CreateUser(ctx context.Context, input model.NewUser)
 	_, err = database.DB.Exec(query, input.SteamID, input.TeamspeakID, elo.Elo,
 		isAdmin, input.Avatar, input.Name)
 	if err != nil {
-		return "", err
+		return "", database.CheckErrorCode(err)
 	}
 
 	return "Created", nil
-- 
2.44.0