67 lines
1.9 KiB
Go
67 lines
1.9 KiB
Go
|
// Copyright 2018 The go-ethereum Authors
|
||
|
|
// This file is part of the go-ethereum library.
|
||
|
|
//
|
||
|
|
// The go-ethereum library is free software: you can redistribute it and/or modify
|
||
|
|
// it under the terms of the GNU Lesser General Public License as published by
|
||
|
|
// the Free Software Foundation, either version 3 of the License, or
|
||
|
|
// (at your option) any later version.
|
||
|
|
//
|
||
|
|
// The go-ethereum library is distributed in the hope that it will be useful,
|
||
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
|
// GNU Lesser General Public License for more details.
|
||
|
|
//
|
||
|
|
// You should have received a copy of the GNU Lesser General Public License
|
||
|
|
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
|
||
|
|
|
||
|
|
package shed
|
||
|
|
|
||
|
|
import (
|
||
|
|
"github.com/syndtr/goleveldb/leveldb"
|
||
|
|
)
|
||
|
|
|
||
|
|
// StringField is the most simple field implementation
|
||
|
|
// that stores an arbitrary string under a specific LevelDB key.
|
||
|
|
type StringField struct {
|
||
|
|
db *DB
|
||
|
|
key []byte
|
||
|
|
}
|
||
|
|
|
||
|
|
// NewStringField retruns a new Instance of StringField.
|
||
|
|
// It validates its name and type against the database schema.
|
||
|
|
func (db *DB) NewStringField(name string) (f StringField, err error) {
|
||
|
|
key, err := db.schemaFieldKey(name, "string")
|
||
|
|
if err != nil {
|
||
|
|
return f, err
|
||
|
|
}
|
||
|
|
return StringField{
|
||
|
|
db: db,
|
||
|
|
key: key,
|
||
|
|
}, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Get returns a string value from database.
|
||
|
|
// If the value is not found, an empty string is returned
|
||
|
|
// an no error.
|
||
|
|
func (f StringField) Get() (val string, err error) {
|
||
|
|
b, err := f.db.Get(f.key)
|
||
|
|
if err != nil {
|
||
|
|
if err == leveldb.ErrNotFound {
|
||
|
|
return "", nil
|
||
|
|
}
|
||
|
|
return "", err
|
||
|
|
}
|
||
|
|
return string(b), nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Put stores a string in the database.
|
||
|
|
func (f StringField) Put(val string) (err error) {
|
||
|
|
return f.db.Put(f.key, []byte(val))
|
||
|
|
}
|
||
|
|
|
||
|
|
// PutInBatch stores a string in a batch that can be
|
||
|
|
// saved later in database.
|
||
|
|
func (f StringField) PutInBatch(batch *leveldb.Batch, val string) {
|
||
|
|
batch.Put(f.key, []byte(val))
|
||
|
|
}
|