From 459b8eb4ab16516974ff616196e4a2593ecbb7b7 Mon Sep 17 00:00:00 2001
From: Ben Johnson <benbjohnson@yahoo.com>
Date: Sun, 16 Feb 2014 15:43:35 -0700
Subject: [PATCH] Read-only transactional block.

---
 db.go           | 18 ++++++++++++++----
 example_test.go | 22 ++++++++++++++++++++++
 node.go         |  2 +-
 3 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/db.go b/db.go
index 0276d7a..b7338c3 100644
--- a/db.go
+++ b/db.go
@@ -359,15 +359,25 @@ func (db *DB) Do(fn func(*RWTransaction) error) error {
 	return t.Commit()
 }
 
-// ForEach executes a function for each key/value pair in a bucket.
-// An error is returned if the bucket cannot be found.
-func (db *DB) ForEach(name string, fn func(k, v []byte) error) error {
+// With executes a function within the context of a Transaction.
+// Any error that is returned from the function is returned from the With() method.
+func (db *DB) With(fn func(*Transaction) error) error {
 	t, err := db.Transaction()
 	if err != nil {
 		return err
 	}
 	defer t.Close()
-	return t.ForEach(name, fn)
+
+	// If an error is returned from the function then pass it through.
+	return fn(t)
+}
+
+// ForEach executes a function for each key/value pair in a bucket.
+// An error is returned if the bucket cannot be found.
+func (db *DB) ForEach(name string, fn func(k, v []byte) error) error {
+	return db.With(func(t *Transaction) error {
+		return t.ForEach(name, fn)
+	})
 }
 
 // Bucket retrieves a reference to a bucket.
diff --git a/example_test.go b/example_test.go
index 542109c..8747f94 100644
--- a/example_test.go
+++ b/example_test.go
@@ -87,6 +87,28 @@ func ExampleDB_Do() {
 	// The value of 'foo' is: bar
 }
 
+func ExampleDB_With() {
+	// Open the database.
+	var db DB
+	db.Open("/tmp/bolt/db_foreach.db", 0666)
+	defer db.Close()
+
+	// Insert data into a bucket.
+	db.CreateBucket("people")
+	db.Put("people", []byte("john"), []byte("doe"))
+	db.Put("people", []byte("susy"), []byte("que"))
+
+	// Access data from within a read-only transactional block.
+	db.With(func(t *Transaction) error {
+		v, _ := t.Get("people", []byte("john"))
+		fmt.Printf("John's last name is %s.\n", string(v))
+		return nil
+	})
+
+	// Output:
+	// John's last name is doe.
+}
+
 func ExampleDB_ForEach() {
 	// Open the database.
 	var db DB
diff --git a/node.go b/node.go
index ec49f11..68f651e 100644
--- a/node.go
+++ b/node.go
@@ -118,7 +118,7 @@ func (n *node) del(key []byte) {
 	index := sort.Search(len(n.inodes), func(i int) bool { return bytes.Compare(n.inodes[i].key, key) != -1 })
 
 	// Exit if the key isn't found.
-	if !bytes.Equal(n.inodes[index].key, key) {
+	if index >= len(n.inodes) || !bytes.Equal(n.inodes[index].key, key) {
 		return
 	}