src/ResourceLister.js
/*
* BSD 3-Clause License
*
* Copyright (c) 2020, Mapcreator
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
import { snake as snakeCase } from 'case';
import { EventEmitter } from 'events';
import Mapcreator from './Mapcreator';
import RequestParameters from './RequestParameters';
import ResourceBase from './resources/base/ResourceBase';
import { isParentOf } from './utils/reflection';
import { makeCancelable } from './utils/helpers';
/**
* Paginated resource lister
*
* @fires ResourceLister#update
*/
export default class ResourceLister extends EventEmitter {
/**
* ResourceLister constructor
*
* @param {Mapcreator} api - Api instance
* @param {string} route - Resource url route
* @param {Class<ResourceBase>} Resource - Resource constructor
* @param {?RequestParameters} parameters - Request parameters
* @param {number} [maxRows=50] - Initial max rows
* @param {string} [key=id] - Key
*/
constructor (api, route, Resource = ResourceBase, parameters = null, maxRows = 50, key = 'id') {
super();
if (!isParentOf(Mapcreator, api)) {
throw new TypeError('Expected api to be of type Mapcreator');
}
this._api = api;
this._Resource = Resource;
this._route = route || new this.Resource(api, {}).baseUrl;
this._parameters = new RequestParameters(parameters || { perPage: RequestParameters.maxPerPage });
this._key = snakeCase(key);
this._waiting = false;
this.autoUpdate = true;
this.maxRows = maxRows;
this._reset();
}
/**
* Get if there are more resources to fetch. It indicates if the maxRows can be increased.
* @returns {boolean} - if more rows are available
*/
get hasMore () {
return typeof this.availableRows === 'undefined' || this.availableRows > this.maxRows;
}
/**
* Get if the instance is waiting for data
* @returns {boolean} - waiting for data
*/
get waiting () {
return this._waiting;
}
/**
* Get the request parameters
* @returns {RequestParameters} - parameters
*/
get parameters () {
return this._parameters;
}
/**
* Set the request parameters
*
* If you set {@link ResourceLister#autoUpdate} to true then {@link ResourceLister#update}
* will automatically be called when the parameters are updated.
* @throws {ResourceLister#autoUpdate}
* @param {RequestParameters} object - parameters
*/
set parameters (object) {
this.parameters.apply(object);
}
/**
* Resource constructor accessor, used for building the resource instance
* @returns {Class<ResourceBase>} - resource constructor
*/
get Resource () {
return this._Resource;
}
/**
* Get the route (url)
* @returns {string} - route
*/
get route () {
return this._route;
}
/**
* Get the data
* @returns {Array<ResourceLister.Resource>} - data
*/
get data () {
return this._data;
}
/**
* Get the api instance
* @returns {Mapcreator} - Api instance
*/
get api () {
return this._api;
}
/**
* Get the row count
*
* @see {ResourceLister.data}
* @returns {number} - row count
*/
get rowCount () {
return this.data.length;
}
/**
* Get the maximum amount of rows allowed
* @returns {number} - max rows
*/
get maxRows () {
return this._maxRows;
}
/**
* Set the maximum amount of rows allowed
* @param {number} value - max rows
*/
set maxRows (value) {
value = Number(value);
if (Number.isNaN(value)) {
throw new TypeError(`Expected maxRows to be numeric got ${typeof raw}`);
}
this._maxRows = value;
if (this.autoUpdate) {
// noinspection JSIgnoredPromiseFromCall
this.update();
}
}
/**
* Get the number of rows the server has available
* @returns {number} - number of rows
*/
get availableRows () {
return this._availableRows;
}
/**
* Set if {@link ResourceLister#update} should be called when {@link ResourceLister#parameters} is updated
*
* @throws {ResourceLister#update}
* @throws {ResourceLister#parameters}
* @param {boolean} value - auto update
*/
set autoUpdate (value) {
value = Boolean(value);
if (this.autoUpdate !== value) {
this._autoUpdate = value;
if (typeof this._boundUpdate === 'undefined') {
this._boundUpdate = this.update.bind(this);
}
if (this.autoUpdate) {
this.parameters.on('change', this._boundUpdate);
} else {
this.parameters.off('change', this._boundUpdate);
}
}
}
/**
* Get if {@link ResourceLister#update} should be called when {@link ResourceLister#parameters} is updated
*
* @throws {ResourceLister#update}
* @throws {ResourceLister#parameters}
*/
get autoUpdate () {
return this._autoUpdate;
}
/**
* Reset the instance
*
* @private
*/
_reset () {
this._parameterToken = this.parameters.token();
this._realData = [];
this._data = [];
this._keys = [];
delete this._availableRows;
}
/**
* Update the server data
*/
async update () {
if (this.waiting) {
return;
}
this._waiting = true;
try {
if (this._parameterToken !== this.parameters.token()) {
this._reset();
}
if (this._realData.length < this.maxRows) {
try {
await this._fetchMore();
} catch (e) {
this.autoUpdate = false;
this.emit('error', e);
throw e;
}
}
if (this.data.length !== this.maxRows) {
this._data = this._realData.slice(0, this.maxRows);
}
} finally {
this._waiting = false;
}
/**
* Update event.
* Called when the ResourceLister has updated
*
* @event RequestLister#update
*/
this.emit('update');
}
/**
* Fetch more data from the server
* @private
* @returns {CancelablePromise}
* @throws {ApiError} - If the api returns errors
*/
_fetchMore () {
const glue = this.route.includes('?') ? '&' : '?';
const parameters = this.parameters.copy();
parameters.offset += this.rowCount;
const endPage = Math.ceil((this.maxRows - this.rowCount) / this.parameters.perPage);
const promises = [];
return makeCancelable(async signal => {
for (; parameters.page <= endPage; parameters.page++) {
const url = this.route + glue + parameters.encode();
const promise = this.api.ky.get(url, { signal });
promises.push(promise);
}
const responses = await Promise.all(promises);
for (const response of responses) {
const { data } = await response.json();
data.forEach(row => this.push(row, false));
this._availableRows = Number(response.headers.get('x-paginate-total')) + parameters.offset;
}
});
}
/**
* Returns the iterable
* @returns {Iterator} - iterator
*/
[Symbol.iterator] () {
return this.data[Symbol.iterator]();
}
/**
* Push a row to the data collection
*
* This will append the row or update an existing row based on the key. If
* autoMaxRows is set to true and maxRows only needs to be increased by one
* for the new resource to show up it will
* @param {ResourceLister.Resource} row - resource
* @param {boolean} autoMaxRows - Increase maxRows if needed
*/
push (row, autoMaxRows = true) {
if (!isParentOf(this.Resource, row)) {
row = new this.Resource(this.api, row);
}
const index = this._keys.findIndex(i => i === row[this._key]);
if (index >= 0) {
this._realData[index] = row;
if (typeof this._data[index] !== 'undefined') {
this._data[index] = row;
}
} else {
this._realData.push(row);
this._keys.push(row[this._key]);
if (autoMaxRows) {
this.maxRows++;
this._data.push(row);
}
}
}
/**
* Same as `this.maxRows += this.parameters.perPage`
* @param {number} [rows=parameters.perPage] - Amount to increment maxRows with
*/
loadMore (rows = this.parameters.perPage) {
this.maxRows += rows;
}
}