index.js

module.exports = function(db) {

    var counter,
        validName = /^[a-zA-Z_$][0-9a-zA-Z_$]*$/

    db.initAutoKeys = function(callback) {
        if (typeof counter != 'undefined') {
            return callback()
        }
        this.get('~counter', function (err, value) {
            if (err) {
                if (err.name === 'NotFoundError') {
                    counter = 0
                } else {
                   throw err
                }
            } else {
               counter = value
            }
            callback()
        })
    }

    db.newAutoKey = function(callback) {
        if (typeof callback != 'function') {
            throw new Error("newKey requires a callback function")
        }
        this.put("~counter", ++counter, function(err) {
            callback(err, counter.toString())
        })
    }

    db.putField = function(key, name, value, options, callback) {
        if (validName.test(name)) {
            this.put(key + ":" + name, value, options, callback)
        } else {
            throw new Error("Invalid char in field name")
        }
    }

    db.getField = function(key, name, options, callback) {
        this.get(key + ":" + name, options, callback)
    }

    db.delField = function(key, name, options, callback) {
        this.del(key + ":" + name, options, callback)
    }

    db.getRecord = function(key, callback) {
        var ret = {}
        this.createReadStream({start: key + ':', end: key + ':\xff'})
            .on('data', function (data) {
                ret[data.key.split(':')[1]] = data.value
            })
            .on('error', function (err) {
                callback(err)
            })
            .on('end', function (err) {
                callback(null, ret)
            })
    }

    db.putRecord = function(key, value, callback) {
        var ops = []
        Object.keys(value).forEach(function(k) {
            ops.push({type: 'put', key: key + ":" + k, value: value[k]})
        })
        this.batch(ops, function (err) {
            callback(err)
        })
    }

    db.delRecord = function(key, callback) {
        var ops = []
        var db = this
        this.createReadStream({start: key + ':', end: key + ':\xff'})
            .on('data', function (data) {
                ops.push({type: 'del', key: data.key})
            })
            .on('error', function (err) {
                callback(err)
            })
            .on('end', function (err) {
                db.batch(ops, function (err) {
                    if (err) return callback(err)
                    callback()
                })
            })
    }
}