owltech
Version:
This a backend for OwlTech Company
203 lines • 7.68 kB
JavaScript
;
/**
* Copyright 2016, Google Inc.
* 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 Google Inc. 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
* OWNER 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, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
Object.defineProperty(exports, "__esModule", { value: true });
const ended = require("is-stream-ended");
const stream_1 = require("stream");
const apiCallable_1 = require("./apiCallable");
class PagedIteration extends apiCallable_1.NormalApiCaller {
/**
* Creates an API caller that returns a stream to performs page-streaming.
*
* @private
* @constructor
* @param {PageDescriptor} pageDescriptor - indicates the structure
* of page streaming to be performed.
*/
constructor(pageDescriptor) {
super();
this.pageDescriptor = pageDescriptor;
}
createActualCallback(request, callback) {
const self = this;
return function fetchNextPageToken(err, response) {
if (err) {
callback(err);
return;
}
const resources = response[self.pageDescriptor.resourceField];
const pageToken = response[self.pageDescriptor.responsePageTokenField];
if (pageToken) {
request[self.pageDescriptor.requestPageTokenField] = pageToken;
callback(err, resources, request, response);
}
else {
callback(err, resources, null, response);
}
};
}
wrap(func) {
const self = this;
return function wrappedCall(argument, metadata, options, callback) {
return func(argument, metadata, options, self.createActualCallback(argument, callback));
};
}
init(settings, callback) {
return super.init(settings, callback);
}
call(apiCall, argument, settings, canceller) {
argument = Object.assign({}, argument);
if (settings.pageToken) {
argument[this.pageDescriptor.requestPageTokenField] = settings.pageToken;
}
if (settings.pageSize) {
argument[this.pageDescriptor.requestPageSizeField] = settings.pageSize;
}
if (!settings.autoPaginate) {
apiCallable_1.NormalApiCaller.prototype.call.call(this, apiCall, argument, settings, canceller);
return;
}
const maxResults = settings.maxResults || -1;
const allResources = [];
function pushResources(err, resources, next) {
if (err) {
canceller.callback(err);
return;
}
for (let i = 0; i < resources.length; ++i) {
allResources.push(resources[i]);
if (allResources.length === maxResults) {
next = null;
break;
}
}
if (!next) {
canceller.callback(null, allResources);
return;
}
setImmediate(apiCall, next, pushResources);
}
setImmediate(apiCall, argument, pushResources);
}
}
exports.PagedIteration = PagedIteration;
class PageDescriptor {
/**
* Describes the structure of a page-streaming call.
*
* @property {String} requestPageTokenField
* @property {String} responsePageTokenField
* @property {String} resourceField
*
* @param {String} requestPageTokenField - The field name of the page token in
* the request.
* @param {String} responsePageTokenField - The field name of the page token in
* the response.
* @param {String} resourceField - The resource field name.
*
* @constructor
*/
constructor(requestPageTokenField, responsePageTokenField, resourceField) {
this.requestPageTokenField = requestPageTokenField;
this.responsePageTokenField = responsePageTokenField;
this.resourceField = resourceField;
}
/**
* Creates a new object Stream which emits the resource on 'data' event.
* @private
* @param {ApiCall} apiCall - the callable object.
* @param {Object} request - the request object.
* @param {CallOptions=} options - the call options to customize the api call.
* @return {Stream} - a new object Stream.
*/
createStream(apiCall, request, options) {
const stream = new stream_1.PassThrough({ objectMode: true });
options = Object.assign({}, options, { autoPaginate: false });
const maxResults = 'maxResults' in options ? options.maxResults : -1;
let pushCount = 0;
let started = false;
function callback(err, resources, next) {
if (err) {
stream.emit('error', err);
return;
}
for (let i = 0; i < resources.length; ++i) {
if (ended(stream)) {
return;
}
if (resources[i] === null) {
continue;
}
stream.push(resources[i]);
pushCount++;
if (pushCount === maxResults) {
stream.end();
}
}
if (ended(stream)) {
return;
}
if (!next) {
stream.end();
return;
}
// When pageToken is specified in the original options, it will overwrite
// the page token field in the next request. Therefore it must be cleared.
if ('pageToken' in options) {
delete options.pageToken;
}
if (stream.isPaused()) {
request = next;
started = false;
}
else {
setImmediate(apiCall, next, options, callback);
}
}
stream.on('resume', () => {
if (!started) {
started = true;
apiCall(request, options, callback);
}
});
return stream;
}
/**
* Returns a new API caller.
* @private
* @return {PageStreamable} - the page streaming caller.
*/
apiCaller() {
return new PagedIteration(this);
}
}
exports.PageDescriptor = PageDescriptor;
//# sourceMappingURL=pagedIteration.js.map