@oat-sa/tao-core-sdk/src/core/cachedStore.js

Core libraries of TAO

/**
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; under version 2
 * of the License (non-upgradable).
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright (c) 2016-2019 (original work) Open Assessment Technologies SA ;
 */
/**
 * @author Jean-Sébastien Conan <jean-sebastien.conan@vesperiagroup.com>
 */
import store from 'core/store';

/**
 * The default name of the key storage indexing the persisted data
 * @type {String}
 */
const defaultKey = 'cachedData';

/**
 * Builds a cached store.
 *
 * Loads a data set from a storage, then maintains persistence of changed values.
 *
 * @param {String} storageName
 * @param {String} storageKey
 * @returns {Promise} Returns a promise that will be resolved with a data accessor
 */
function cachedStoreFactory(storageName, storageKey) {
    storageKey = storageKey || defaultKey;

    return store(storageName).then(function (storage) {
        return storage.getItem(storageKey).then(function (data) {
            // the persisted data set is always an object
            data = data || {};

            // just provide a data accessor that:
            // - immediately gets the values
            // - stores the changes through a promise.
            return {
                /**
                 * Gets a value from the data
                 * @param {String} name
                 * @returns {Object}
                 */
                getItem(name) {
                    return data[name];
                },

                /**
                 * Sets a value in the data, then ensure the data will persist
                 * @param {String} name
                 * @param {Object} value
                 * @returns {Promise} Returns a promise that will be resolved if the data have been successfully stored
                 */
                setItem(name, value) {
                    data[name] = value;
                    return storage.setItem(storageKey, data);
                },

                /**
                 * Removes a value from the data, then synchronise the data set with the storage
                 * @param {String} name
                 * @returns {Promise} Returns a promise that will be resolved if the data have been successfully stored
                 */
                removeItem(name) {
                    data[name] = void 0;
                    return storage.setItem(storageKey, data);
                },

                /**
                 * Clears the full data set
                 * @returns {Promise} Returns a promise that will be resolved if the data have been successfully erased
                 */
                clear() {
                    data = {};
                    return storage.removeItem(storageKey);
                },

                /**
                 * Delete the database related to the current store
                 * @returns {Promise} with true in resolve once cleared
                 */
                removeStore() {
                    data = {};
                    return storage.removeStore();
                }
            };
        });
    });
}

export default cachedStoreFactory;