I am working on a Flatiron Union-based app, and it seems that the simple logger I am developing logs before the routes are run, so it does not accurately report what happened. I took the logger sample code from the Union examples. Here's a stripped down code sample:
var
union = require('union')
, server;
server = union.createServer({
before: [ function (req,res) {
console.log('before');
res.writeHead(404, {"Content-Type": "text/plain"});
res.end("Hello World");
} ],
after: [
function LoggerStream() {
var stream = new union.ResponseStream();
stream.once("pipe", function (req) {
console.log({res: this.res.statusCode, method: this.req.method});
});
return stream;
}
]
});
server.listen(8800);
console.log('union running on 8800');
Here's what appears in my console:
$ DEBUG=* node ./union.js
union running on 8800
{ res: 200, method: 'GET' }
before
Note that the reported status is 200 when the http server actually returned a 404.
Why is this running out of order?
Here's a recent reply to your question from our mailing list by indexzero:
Stuart,
This is actually expected behavior. A pipe chain is constructed by a
union.RoutingStream instance from:
union.ResponseStream() --> after0 --> after1 --> after2 --> ... -->
aftern --> http.Response() (see
https://github.com/flatiron/union/blob/master/lib/routing-stream.js#L74-83)
So the pipe event on every Stream in the after chain is invoked
immediately, but everyone of those Streams has an opportunity to
modify the data sent to the response by implementing their own .pipe()
method.
So for example if your LoggingStream was
var stream = new union.ResponseStream(); stream.once("data",
function (req) { console.log({res: this.res.statusCode, method:
this.req.method}); }); return stream;
You would see the console.log statements fire in the order you expect.
It might be useful to read Max Ogden's recent blog post on Streams in
node.js and how they work: http://maxogden.com/node-streams
Cheers, Charlie
If you have more questions, you can find us on github, irc (#nodejitsu on freenode) and our mailing list at flatironjs#googlegroups.com . :)
Related
I have found a few examples of context.getTwilioClient(), but I have not been able to locate any online documentation. It's probably right under my nose, but it is eluding me. In particular, I'm trying to get information about workers in a Task Router queue (i.e., how many workers are in the different statuses and how many workers are available), but having the documentation will help with future projects.
I found some documentation saying that the context.getTwilioClient(), "enables you to invoke the getTwilioClient method on the context object for a fully-initialized Twilio REST API client." (https://support.twilio.com/hc/en-us/articles/115007737928-Getting-Started-with-Twilio-Functions)
It then shows this example, but there is no implementation of "messages" when I attempt to run this code:
var client = context.getTwilioClient();
client.messages.create({
to: '+12025551212',
from: '+12065551212',
body: "hello world!"})
Thanks.
The messages property should be on the client. getTwilioClient returns the Twilio helper library for Node.js.
I just created a Function with your code, and it worked as expected, meaning that I got the SMS, however, the function did time out because the callback was never invoked. To end the function invocation and respond to the caller, make sure you always invoke the callback function, like this:
exports.handler = function(context, event, callback) {
var client = context.getTwilioClient();
client.messages.create({
to: '+1xxxxxxxxxx',
from: '+1xxxxxxxxxxx',
body: "hello world!"})
.then((message) => {
console.log('SMS successfully sent');
console.log(message.sid);
// Make sure to only call `callback` once everything is finished, and to pass
// null as the first parameter to signal successful execution.
return callback(null, `Success! Message SID: ${message.sid}`);
})
.catch((error) => {
console.error(error);
return callback(error);
});
};
You can learn more about the callback function here.
If you still encounter this issue, can you tell use what Node Version you're using and which module dependencies and their versions?
You can find these details at Settings & More > Dependencies in your Twilio Functions Service.
We upload a document from SAPUI5 to our SAP System using the CREATE_STREAM Method of the oData Service in ABAP. The creation of the document works fine.
What we would like to achieve is to get the response back to SAPUI5. Especially when there is an error during the creation of the document in the backend.
In Frontend we use the uploadSet Control.
...oUploadSet.uploadItem(oItem);
In the Backend we create a message with
...lo_message_container->add_message( iv_msg_type = /iwbep/cl_cos_logger=>error
iv_msg_number = '018'
iv_msg_id = lv_msg_id
iv_add_to_response_header = abap_true
)....
We can find the created message in the error protocol of our gateway server (/IWFND/ERROR_LOG). But how can this message be retrieved in SAPUI5 and used in the MessageManger Control?
We tried the onUploadCompleted Control but we can't find any response data there.
Can somebody explain how the response or a message header from the CREAT_STREAM method can be used in SAPUI5?
The "new" UploadSet control is kinda half-baked imo. The response will get lost in some internal method. This internal method will then trigger onUploadCompleted and you get nothing but useless information.
Lucky for us we can easily overwrite this internal stuff. UploadSet has an aggregation Uploader. We have to provide our own Uploader. Problem solved. Here is the line that needs to be modified.
sap.ui.define([
"sap/m/upload/Uploader",
...
], function (Uploader, ...) {
return Uploader.extend("my.custom.control.Uploader", {
uploadItem: function (oItem, aHeaders) {
// beginning of the method. take it from the official sources
oXhr.onreadystatechange = function () {
const oHandler = that._mRequestHandlers[oItem.getId()];
if (this.readyState === window.XMLHttpRequest.DONE && !oHandler.aborted) {
// we need to return the xhr object. it contains the response!
that.fireUploadCompleted({ item: oItem, xhr: oXhr });
}
};
// .. rest of the method
}
});
});
Use it like this
<mvc:View xmlns:custom="my.custom.control" ....>
<UploadSet items="....">
.....
<uploader>
<custom:Uploader uploadUrl="......"
uploadCompleted=".onUploadCompleted"
uploadStarted=".onUploadStarted" />
</uploader>
</UploadSet>
Edit: Your own uploader also means implementing your own event handlers (uploadAborted, uploadCompleted, uploadProgressed, uploadStarted). See the official documentation for more information about the events.
Using express and Node.js, I'm using the twitter streaming API and the needle npm package for accessing APIs to pull tweets related to keywords. The streaming is functional and I am successfully pulling tweets using the following (simplified) code:
const needle = require('needle');
const TOKEN = // My Token
const streamURL = 'https://api.twitter.com/2/tweets/search/stream';
function streamTweets() {
const stream = needle.get(streamURL, {
headers: {
Authorization: `Bearer ${TOKEN}`
}
});
stream.on('data', (data) => {
try {
const json = JSON.parse(data); // This line appears to be causing my error
const text = json.data.text;
} catch (error) {
console.log("error");
}
});
}
However, no matter which search term I use (and the subsequent large or small volume of tweets coming through), the catch block will consistently log 1-3 errors per minute, which look like this:
SyntaxError: Unexpected end of JSON input
at JSON.parse (<anonymous>)
at PassThrough.<anonymous> (C:\Users\danie\OneDrive\Documents\Personal-Projects\twitter-program\server.js:56:31)
at PassThrough.emit (events.js:315:20)
at addChunk (internal/streams/readable.js:309:12)
at readableAddChunk (internal/streams/readable.js:284:9)
at PassThrough.Readable.push (internal/streams/readable.js:223:10)
at PassThrough.Transform.push (internal/streams/transform.js:166:32)
at PassThrough.afterTransform (internal/streams/transform.js:101:10)
at PassThrough._transform (internal/streams/passthrough.js:46:3)
at PassThrough.Transform._read (internal/streams/transform.js:205:10).
I've seen previous advice which says that data can be fired in multiple chunks, and to push the chunks to an array i.e. something like the following:
let chunks = [];
stream.on('data', (dataChunk) => {
chunks.push(dataChunk);
}).on('end',() => {
// combine chunks to create JSON object
})
But this didn't work either (may have been my implementation but I don't think so) and now I'm wondering if it's perhaps an error with the twitter API, because most of the tweet objects do come through correctly. I should note that the streamTweets() function above is called from an async function, and I am also wondering if that is having something to do with it.
Has anyone else encountered this error? Or does anyone have any idea how I might be fix it? Ideally i'd like 100% of the tweets to stream correctly.
Thanks in advance!
For future readers, this error is triggered by Twitter's heartbeat message that is sent every 20 seconds. Per the documentation:
The endpoint provides a 20-second keep alive heartbeat (it will look like a new line character).
Adding a guard against parsing the empty string will prevent the JSON parsing error.
if (data === "")
return
An empty string is invalid JSON, hence the emitted error.
Now, acknowledging that the heartbeat exists, it may be beneficial to add read_timeout = 20 * 1000 in the needle request to avoiding a stalled program with no data, be that due to a local network outage or DNS miss, etc.
I am new to Service Workers, and have had a look through the various bits of documentation (Google, Mozilla, serviceworke.rs, Github, StackOverflow questions). The most helpful is the ServiceWorkers cookbook.
Most of the documentation seems to point to caching entire pages so that the app works completely offline, or redirecting the user to an offline page until the browser can redirect to the internet.
What I want to do, however, is store my form data locally so my web app can upload it to the server when the user's connection is restored. Which "recipe" should I use? I think it is Request Deferrer. Do I need anything else to ensure that Request Deferrer will work (apart from the service worker detector script in my web page)? Any hints and tips much appreciated.
Console errors
The Request Deferrer recipe and code doesn't seem to work on its own as it doesn't include file caching. I have added some caching for the service worker library files, but I am still getting this error when I submit the form while offline:
Console: {"lineNumber":0,"message":
"The FetchEvent for [the form URL] resulted in a network error response:
the promise was rejected.","message_level":2,"sourceIdentifier":1,"sourceURL":""}
My Service Worker
/* eslint-env es6 */
/* eslint no-unused-vars: 0 */
/* global importScripts, ServiceWorkerWare, localforage */
importScripts('/js/lib/ServiceWorkerWare.js');
importScripts('/js/lib/localforage.js');
//Determine the root for the routes. I.e, if the Service Worker URL is http://example.com/path/to/sw.js, then the root is http://example.com/path/to/
var root = (function() {
var tokens = (self.location + '').split('/');
tokens[tokens.length - 1] = '';
return tokens.join('/');
})();
//By using Mozilla’s ServiceWorkerWare we can quickly setup some routes for a virtual server. It is convenient you review the virtual server recipe before seeing this.
var worker = new ServiceWorkerWare();
//So here is the idea. We will check if we are online or not. In case we are not online, enqueue the request and provide a fake response.
//Else, flush the queue and let the new request to reach the network.
//This function factory does exactly that.
function tryOrFallback(fakeResponse) {
//Return a handler that…
return function(req, res) {
//If offline, enqueue and answer with the fake response.
if (!navigator.onLine) {
console.log('No network availability, enqueuing');
return enqueue(req).then(function() {
//As the fake response will be reused but Response objects are one use only, we need to clone it each time we use it.
return fakeResponse.clone();
});
}
//If online, flush the queue and answer from network.
console.log('Network available! Flushing queue.');
return flushQueue().then(function() {
return fetch(req);
});
};
}
//A fake response with a joke for when there is no connection. A real implementation could have cached the last collection of updates and keep a local model. For simplicity, not implemented here.
worker.get(root + 'api/updates?*', tryOrFallback(new Response(
JSON.stringify([{
text: 'You are offline.',
author: 'Oxford Brookes University',
id: 1,
isSticky: true
}]),
{ headers: { 'Content-Type': 'application/json' } }
)));
//For deletion, let’s simulate that all went OK. Notice we are omitting the body of the response. Trying to add a body with a 204, deleted, as status throws an error.
worker.delete(root + 'api/updates/:id?*', tryOrFallback(new Response({
status: 204
})));
//Creation is another story. We can not reach the server so we can not get the id for the new updates.
//No problem, just say we accept the creation and we will process it later, as soon as we recover connectivity.
worker.post(root + 'api/updates?*', tryOrFallback(new Response(null, {
status: 202
})));
//Start the service worker.
worker.init();
//By using Mozilla’s localforage db wrapper, we can count on a fast setup for a versatile key-value database. We use it to store queue of deferred requests.
//Enqueue consists of adding a request to the list. Due to the limitations of IndexedDB, Request and Response objects can not be saved so we need an alternative representations.
//This is why we call to serialize().`
function enqueue(request) {
return serialize(request).then(function(serialized) {
localforage.getItem('queue').then(function(queue) {
/* eslint no-param-reassign: 0 */
queue = queue || [];
queue.push(serialized);
return localforage.setItem('queue', queue).then(function() {
console.log(serialized.method, serialized.url, 'enqueued!');
});
});
});
}
//Flush is a little more complicated. It consists of getting the elements of the queue in order and sending each one, keeping track of not yet sent request.
//Before sending a request we need to recreate it from the alternative representation stored in IndexedDB.
function flushQueue() {
//Get the queue
return localforage.getItem('queue').then(function(queue) {
/* eslint no-param-reassign: 0 */
queue = queue || [];
//If empty, nothing to do!
if (!queue.length) {
return Promise.resolve();
}
//Else, send the requests in order…
console.log('Sending ', queue.length, ' requests...');
return sendInOrder(queue).then(function() {
//Requires error handling. Actually, this is assuming all the requests in queue are a success when reaching the Network.
// So it should empty the queue step by step, only popping from the queue if the request completes with success.
return localforage.setItem('queue', []);
});
});
}
//Send the requests inside the queue in order. Waiting for the current before sending the next one.
function sendInOrder(requests) {
//The reduce() chains one promise per serialized request, not allowing to progress to the next one until completing the current.
var sending = requests.reduce(function(prevPromise, serialized) {
console.log('Sending', serialized.method, serialized.url);
return prevPromise.then(function() {
return deserialize(serialized).then(function(request) {
return fetch(request);
});
});
}, Promise.resolve());
return sending;
}
//Serialize is a little bit convolved due to headers is not a simple object.
function serialize(request) {
var headers = {};
//for(... of ...) is ES6 notation but current browsers supporting SW, support this notation as well and this is the only way of retrieving all the headers.
for (var entry of request.headers.entries()) {
headers[entry[0]] = entry[1];
}
var serialized = {
url: request.url,
headers: headers,
method: request.method,
mode: request.mode,
credentials: request.credentials,
cache: request.cache,
redirect: request.redirect,
referrer: request.referrer
};
//Only if method is not GET or HEAD is the request allowed to have body.
if (request.method !== 'GET' && request.method !== 'HEAD') {
return request.clone().text().then(function(body) {
serialized.body = body;
return Promise.resolve(serialized);
});
}
return Promise.resolve(serialized);
}
//Compared, deserialize is pretty simple.
function deserialize(data) {
return Promise.resolve(new Request(data.url, data));
}
var CACHE = 'cache-only';
// On install, cache some resources.
self.addEventListener('install', function(evt) {
console.log('The service worker is being installed.');
// Ask the service worker to keep installing until the returning promise
// resolves.
evt.waitUntil(precache());
});
// On fetch, use cache only strategy.
self.addEventListener('fetch', function(evt) {
console.log('The service worker is serving the asset.');
evt.respondWith(fromCache(evt.request));
});
// Open a cache and use `addAll()` with an array of assets to add all of them
// to the cache. Return a promise resolving when all the assets are added.
function precache() {
return caches.open(CACHE).then(function (cache) {
return cache.addAll([
'/js/lib/ServiceWorkerWare.js',
'/js/lib/localforage.js',
'/js/settings.js'
]);
});
}
// Open the cache where the assets were stored and search for the requested
// resource. Notice that in case of no matching, the promise still resolves
// but it does with `undefined` as value.
function fromCache(request) {
return caches.open(CACHE).then(function (cache) {
return cache.match(request).then(function (matching) {
return matching || Promise.reject('no-match');
});
});
}
Here is the error message I am getting in Chrome when I go offline:
(A similar error occurred in Firefox - it falls over at line 409 of ServiceWorkerWare.js)
ServiceWorkerWare.prototype.executeMiddleware = function (middleware,
request) {
var response = this.runMiddleware(middleware, 0, request, null);
response.catch(function (error) { console.error(error); });
return response;
};
this is a little more advanced that a beginner level. But you will need to detect when you are offline or in a Li-Fi state. Instead of POSTing data to an API or end point you need to queue that data to be synched when you are back on line.
This is what the Background Sync API should help with. However, it is not supported across the board just yet. Plus Safari.........
So maybe a good strategy is to persist your data in IndexedDB and when you can connect (background sync fires an event for this) you would then POST the data. It gets a little more complex for browsers that don't support service workers (Safari) or don't yet have Background Sync (that will level out very soon).
As always design your code to be a progressive enhancement, which can be tricky, but worth it in the end.
Service Workers tend to cache the static HTML, CSS, JavaScript, and image files.
I need to use PouchDB and sync it with CouchDB
Why CouchDB?
CouchDB is a NoSQL database consisting of a number of Documents
created with JSON.
It has versioning (each document has a _rev
property with the last modified date)
It can be synchronised with
PouchDB, a local JavaScript application that stores data in local
storage via the browser using IndexedDB. This allows us to create
offline applications.
The two databases are both “master” copies of
the data.
PouchDB is a local JavaScript implementation of CouchDB.
I still need a better answer than my partial notes towards a solution!
Yes, this type of service worker is the correct one to use for saving form data offline.
I have now edited it and understood it better. It caches the form data, and loads it on the page for the user to see what they have entered.
It is worth noting that the paths to the library files will need editing to reflect your local directory structure, e.g. in my setup:
importScripts('/js/lib/ServiceWorkerWare.js');
importScripts('/js/lib/localforage.js');
The script is still failing when offline, however, as it isn't caching the library files. (Update to follow when I figure out caching)
Just discovered an extra debugging tool for service workers (apart from the console): chrome://serviceworker-internals/. In this, you can start or stop service workers, view console messages, and the resources used by the service worker.
I'm trying to integrate Medium blogging into an app by showing some cards with posts images and links to the original Medium publication.
From Medium API docs I can see how to retrieve publications and create posts, but it doesn't mention retrieving posts. Is retrieving posts/stories for a user currently possible using the Medium's API?
The API is write-only and is not intended to retrieve posts (Medium staff told me)
You can simply use the RSS feed as such:
https://medium.com/feed/#your_profile
You can simply get the RSS feed via GET, then if you need it in JSON format just use a NPM module like rss-to-json and you're good to go.
Edit:
It is possible to make a request to the following URL and you will get the response. Unfortunately, the response is in RSS format which would require some parsing to JSON if needed.
https://medium.com/feed/#yourhandle
⚠️ The following approach is not applicable anymore as it is behind Cloudflare's DDoS protection.
If you planning to get it from the Client-side using JavaScript or jQuery or Angular, etc. then you need to build an API gateway or web service that serves your feed. In the case of PHP, RoR, or any server-side that should not be the case.
You can get it directly in JSON format as given beneath:
https://medium.com/#yourhandle/latest?format=json
In my case, I made a simple web service in the express app and host it over Heroku. React App hits the API exposed over Heroku and gets the data.
const MEDIUM_URL = "https://medium.com/#yourhandle/latest?format=json";
router.get("/posts", (req, res, next) => {
request.get(MEDIUM_URL, (err, apiRes, body) => {
if (!err && apiRes.statusCode === 200) {
let i = body.indexOf("{");
const data = body.substr(i);
res.send(data);
} else {
res.sendStatus(500).json(err);
}
});
});
Nowadays this URL:
https://medium.com/#username/latest?format=json
sits behind Cloudflare's DDoS protection service so instead of consistently being served your feed in JSON format, you will usually receive instead an HTML which is suppose to render a website to complete a reCAPTCHA and leaving you with no data from an API request.
And the following:
https://medium.com/feed/#username
has a limit of the latest 10 posts.
I'd suggest this free Cloudflare Worker that I made for this purpose. It works as a facade so you don't have to worry about neither how the posts are obtained from source, reCAPTCHAs or pagination.
Full article about it.
Live example. To fetch the following items add the query param ?next= with the value of the JSON field next which the API provides.
const MdFetch = async (name) => {
const res = await fetch(
`https://api.rss2json.com/v1/api.json?rss_url=https://medium.com/feed/${name}`
);
return await res.json();
};
const data = await MdFetch('#chawki726');
To get your posts as JSON objects
you can replace your user name instead of #USERNAME.
https://api.rss2json.com/v1/api.json?rss_url=https://medium.com/feed/#USERNAME
With that REST method you would do this: GET https://api.medium.com/v1/users/{{userId}}/publications and this would return the title, image, and the item's URL.
Further details: https://github.com/Medium/medium-api-docs#32-publications .
You can also add "?format=json" to the end of any URL on Medium and get useful data back.
Use this url, this url will give json format of posts
Replace studytact with your feed name
https://api.rss2json.com/v1/api.json?rss_url=https://medium.com/feed/studytact
I have built a basic function using AWS Lambda and AWS API Gateway if anyone is interested. A detailed explanation is found on this blog post here and the repository for the the Lambda function built with Node.js is found here on Github. Hopefully someone here finds it useful.
(Updating the JS Fiddle and the Clay function that explains it as we updated the function syntax to be cleaner)
I wrapped the Github package #mark-fasel was mentioning below into a Clay microservice that enables you to do exactly this:
Simplified Return Format: https://www.clay.run/services/nicoslepicos/medium-get-user-posts-new/code
I put together a little fiddle, since a user was asking how to use the endpoint in HTML to get the titles for their last 3 posts:
https://jsfiddle.net/h405m3ma/3/
You can call the API as:
curl -i -H "Content-Type: application/json" -X POST -d '{"username":"nicolaerusan"}' https://clay.run/services/nicoslepicos/medium-get-users-posts-simple
You can also use it easily in your node code using the clay-client npm package and just write:
Clay.run('nicoslepicos/medium-get-user-posts-new', {"profile":"profileValue"})
.then((result) => {
// Do what you want with returned result
console.log(result);
})
.catch((error) => {
console.log(error);
});
Hope that's helpful!
Check this One you will get all info about your own post........
mediumController.getBlogs = (req, res) => {
parser('https://medium.com/feed/#profileName', function (err, rss) {
if (err) {
console.log(err);
}
var stories = [];
for (var i = rss.length - 1; i >= 0; i--) {
var new_story = {};
new_story.title = rss[i].title;
new_story.description = rss[i].description;
new_story.date = rss[i].date;
new_story.link = rss[i].link;
new_story.author = rss[i].author;
new_story.comments = rss[i].comments;
stories.push(new_story);
}
console.log('stories:');
console.dir(stories);
res.json(200, {
Data: stories
})
});
}
I have created a custom REST API to retrieve the stats of a given post on Medium, all you need is to send a GET request to my custom API and you will retrieve the stats as a Json abject as follows:
Request :
curl https://endpoint/api/stats?story_url=THE_URL_OF_THE_MEDIUM_STORY
Response:
{
"claps": 78,
"comments": 1
}
The API responds within a reasonable response time (< 2 sec), you can find more about it in the following Medium article.