loopback-component-storage/lib/factory.js

125 lines
3.3 KiB
JavaScript

// Copyright IBM Corp. 2013,2014. All Rights Reserved.
// Node module: loopback-component-storage
// This file is licensed under the Artistic License 2.0.
// License text available at https://opensource.org/licenses/Artistic-2.0
'use strict';
var pkgcloud = require('pkgcloud');
/*!
* Patch the prototype for a given subclass of Container or File
* @param {Function} cls The subclass
*/
function patchBaseClass(cls) {
var proto = cls.prototype;
var found = false;
// Find the prototype that owns the _setProperties method
while (proto &&
proto.constructor !== pkgcloud.storage.Container &&
proto.constructor !== pkgcloud.storage.File) {
if (proto.hasOwnProperty('_setProperties')) {
found = true;
break;
} else {
proto = Object.getPrototypeOf(proto);
}
}
if (!found) {
proto = cls.prototype;
}
var m1 = proto._setProperties;
proto._setProperties = function(details) {
// Use an empty object to receive the calculated properties from details
var receiver = {};
// Pass in some context as non-enumerable properties
Object.defineProperties(receiver, {
client: {value: this.client},
files: {value: this.files},
});
m1.call(receiver, details);
// Apply the calculated properties to this
for (var p in receiver) {
this[p] = receiver[p];
}
// Keep references to raw and the calculated properties
this._rawMetadata = details;
this._metadata = receiver; // Use _metadata to avoid conflicts
};
proto.toJSON = function() {
return this._metadata;
};
proto.getMetadata = function() {
return this._metadata;
};
proto.getRawMetadata = function() {
return this._rawMetadata;
};
}
/*!
* Patch the pkgcloud Container/File classes so that the metadata are separately
* stored for JSON serialization
*
* @param {String} provider The name of the storage provider
*/
function patchContainerAndFileClass(provider) {
var storageProvider = getProvider(provider).storage;
patchBaseClass(storageProvider.Container);
patchBaseClass(storageProvider.File);
}
/**
* Create a client instance based on the options
* @param options
* @returns {*}
*/
function createClient(options) {
options = options || {};
var provider = options.provider || 'filesystem';
var handler;
try {
// Try to load the provider from providers folder
handler = require('./providers/' + provider);
} catch (err) {
try {
// Fall back to using an external provider
handler = require(provider);
if (!handler || !handler.createClient) {
// Fall back to pkgcloud
handler = require('pkgcloud').storage;
}
} catch (err) {
// Fall back to pkgcloud
handler = require('pkgcloud').storage;
}
}
patchContainerAndFileClass(provider);
return handler.createClient(options);
}
/**
* Look up a provider by name
* @param provider
* @returns {*}
*/
function getProvider(provider) {
try {
// Try to load the provider from providers folder
return require('./providers/' + provider);
} catch (err) {
try {
// Fall back to using an external provider
return require(provider);
} catch (err) {
// Fall back to pkgcloud
return require('pkgcloud').providers[provider];
}
}
}
module.exports.createClient = createClient;
module.exports.getProvider = getProvider;