"use strict";
const fs = require('fs');
const path = require('path');
const Storage = require('./Storage');
/**
* Collection served from file system storage.
*
* Very useful for rapid prototyping.
*/
class FSStorage extends Storage
{
/**
* @param {StorageOptions} options see fields
*/
constructor(options)
{
super(options)
/**
* folder path where data is kept
*/
this.dirname = options.connectionString;
try
{
if (!fs.existsSync(this.dirname))
{
fs.mkdirSync(this.dirname);
}
}
catch (e)
{
}
/**
* Mapping between id and last modified data.
*/
this.list = this.listItems();
}
/**
* Return a mapping between record id and last modified data at directory.
* Used for update checking.
*/
listItems()
{
let output = {};
for (let file of fs.readdirSync(this.dirname))
{
Eif (file.match(/\.json$/))
{
let stat = fs.statSync(path.join(this.dirname, file));
Eif (stat.isFile())
{
output[file.substr(0, file.length - 5)] = stat.mtime;
}
}
}
return output;
}
/** @override */
readAllRecords()
{
let output = [];
for (let key in this.list)
{
let query = {};
query[this.primaryKey] = key;
output.push(this.readRecord(query));
}
return Promise.all(output);
}
/** @override */
createRecord(record)
{
return this.updateRecord(record);
}
/** @override */
readRecord(record)
{
return new Promise((resolve, reject) =>
{
let key = record[this.primaryKey];
try
{
resolve(JSON.parse(fs.readFileSync(path.join(this.dirname, key + '.json'))));
}
catch (e)
{
reject(e);
}
});
}
/** @override */
updateRecord(record)
{
return new Promise((resolve, reject) =>
{
let key = record[this.primaryKey];
let file = path.join(this.dirname, key + '.json');
fs.writeFileSync(file, JSON.stringify(record, null, 1));
let stat = fs.statSync(file);
this.list[key] = stat.mtime;
resolve(JSON.parse(fs.readFileSync(file)));
});
}
/** @override */
deleteRecord(record)
{
return new Promise((resolve, reject) =>
{
let key = record[this.primaryKey];
let file = path.join(this.dirname, key + '.json');
fs.unlinkSync(file);
delete this.list[key];
resolve(record);
});
}
/** @override */
async updateCheckImpl()
{
let updated = false;
let newlist = this.listItems(),
list = this.list,
type, record = {};
// check for deleted item
type = 'delete';
for (let item in list)
{
if (!newlist[item])
{
record[this.primaryKey] = item;
this.emit(type, record);
delete list[item];
updated = true;
}
}
// check for new items
type = 'create';
for (let item in newlist)
{
if (!list[item])
{
record = JSON.parse(fs.readFileSync(path.join(this.dirname, item + '.json')));
this.emit(type, record);
list[item] = newlist[item];
updated = true;
}
}
// check for modified items
type = 'update';
for (let item in list)
{
if (list[item].getTime() !== newlist[item].getTime())
{
record = JSON.parse(fs.readFileSync(path.join(this.dirname, item + '.json')));
this.emit(type, record);
list[item] = newlist[item];
updated = true;
}
}
return updated;
}
}
module.exports = FSStorage;
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