Uses a separate slice to make DeleteAll safe.

txn.go

@@ -258,19 +258,27 @@ func (txn *Txn) DeleteAll(table, index string, args ...interface{}) (int, error)
 		return 0, fmt.Errorf("cannot delete in read-only transaction")
 	}
 
-	// Get all the objects
+	// Get all the objects.
 	iter, err := txn.Get(table, index, args...)
 	if err != nil {
 		return 0, err
 	}
 
-	// Delete all
-	var num int
+	// Put them into a slice so there are no safety concerns while actually
+	// performing the deletes.
+	var objs []interface{}
 	for {
 		obj := iter.Next()
 		if obj == nil {
 			break
 		}
+
+		objs = append(objs, obj)
+	}
+
+	// Do the deletes.
+	num := 0
+	for _, obj := range(objs) {
 		if err := txn.Delete(table, obj); err != nil {
 			return num, err
 		}

txn_test.go

@@ -391,13 +391,22 @@ func TestTxn_DeleteAll_Simple(t *testing.T) {
 		t.Fatalf("err: %v", err)
 	}
 
+	// Do a delete that doesn't hit any objects
+	num, err := txn.DeleteAll("main", "id", "dogs")
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if num != 0 {
+		t.Fatalf("bad: %d", num)
+	}
+
 	// Delete a specific ID
-	num, err := txn.DeleteAll("main", "id", obj1.ID)
+	num, err = txn.DeleteAll("main", "id", obj1.ID)
 	if err != nil {
 		t.Fatalf("err: %v", err)
 	}
 	if num != 1 {
-		t.Fatalf("Bad: %d", num)
+		t.Fatalf("bad: %d", num)
 	}
 
 	// Ensure we cannot lookup
@@ -428,6 +437,55 @@ func TestTxn_DeleteAll_Simple(t *testing.T) {
 	}
 }
 
+func TestTxn_DeleteAll_Prefix(t *testing.T) {
+	db := testDB(t)
+	txn := db.Txn(true)
+
+	obj1 := &TestObject{
+		ID:  "my-object",
+		Foo: "abc",
+	}
+	obj2 := &TestObject{
+		ID:  "my-cool-thing",
+		Foo: "xyz",
+	}
+	obj3 := &TestObject{
+		ID:  "my-other-cool-thing",
+		Foo: "xyz",
+	}
+
+	err := txn.Insert("main", obj1)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	err = txn.Insert("main", obj2)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	err = txn.Insert("main", obj3)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	// Delete a prefix
+	num, err := txn.DeleteAll("main", "id_prefix", "my-")
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if num != 3 {
+		t.Fatalf("bad: %d", num)
+	}
+
+	// Ensure we cannot lookup
+	raw, err := txn.First("main", "id_prefix", "my-")
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if raw != nil {
+		t.Fatalf("bad: %#v", raw)
+	}
+}
+
 func TestTxn_InsertGet_Prefix(t *testing.T) {
 	db := testDB(t)
 	txn := db.Txn(true)