I have this simple Rails app that connects to a MySQL database locally.
I have separate Ruby application that runs on its own (the Rails app does not know of the Ruby app's existence) and makes changes to that same database.
Currently, the home page of the Rails app displays the contents of a single table statically. Is there a way to display the contents dynamically? Where as the Ruby application is doing its own thing and Rails just sits there displaying everything that is currently happening within the database without refreshing or clicking any button.
Edit: My intent for the Rails app is to create a custom Web Interface for the database. If possible, I am trying to avoid SSEs since I've read that SSEs are not compatible with IE.
You can build the dynamic portion of the display as an Ajax-oriented display, and then in javascript use a timer to regularly kick off an Ajax-based update to the form information.
How to do this is highly dependent on what you're displaying and how your data is structured. You will want to have a way to identify time-based changes to the data, in order to tell when the last update happened, so that you don't send all of the form data when nothing has changed.
A complete solution is fairly complicated, and far beyond the scope of what can be covered in a SO answer. If you're learning, it's a good exercise for design and developing some great Rails skills. However, if it's a pressing need for an existing system, you might want to consider finding a freelancer to help develop it.
Related
I'm learning full stack development through the free course at appacademy. If you are familiar with it. am almost finished with the rails section and have done also done the SQL & Ruby sections. I have yet to start JavaScript or React.
To test my abilities, I want to create an app. It will mostly be backend + HTML since I haven't covered front end yet.
The app function: ability for someone to provide a list of URLs for reddit posts and then track number of upvotes. I want to do this by scraping the reddit content using this. This is just to test my ability and not a real use case.
I only want to scrape once a day to keep the scraping function minimal. I also want to add a refresh button next to each post, so the user can refresh when they want to.
Questions:
Ill be creating a database that stores the value of upvotes. However, from what I have learned with the program, I do not know how I can use my ruby app to keep running my daily scraper function. If I create a file scraper.rb with the function that is on a time loop, how do I put this file in my ror created app? do i put it in the models, views or controllers folder? Will it run automatically if I run my ruby server? or is this part entirely separate? do I run two ruby apps at once? One for backends and one the actual page
For the refresh button, I think I would need to include a call to the scraper function in my controller before rendering the refreshed text. Does that sound right?
From your description, I would say that the scraper should be a model method and it needs to be wrapped around a rake task.
There are many ways you can achieve the periodic execution. Some of them are:
Whenever gem
Plain old cron job for running the rake task
If you deploy it in a PaaS like heroku, render.com or something similar, there are addons which can be configured to do the cron,like heroku scheduler or render.com cron.
I'm a fairly experienced dev but I'm a total web and rails newbie. I'm trying to implement a kind of market place rails application. I've developed the app to where I'm far along in the customer interaction flow and now I'm realizing I need to automate stuff cause dev/test via browser consumes so much time.
Say I have customer interaction flow that goes from page A, then to page B, C, D...G. And now I'm developing the 'H' page. I know I could use the automated test facilities (e.g. Minitest) to automate the whole thing. But being as how I still have my rails training wheels on sometimes I like to see database state progress from one state to the next for myself rather than just trust that the test automation really is doing what I'm expecting.
My question is, is there a way to have Minitest automate/simulate the user interaction flow from A -> G and then let me take over in a manual way from there such that I could click my newly-developed browser button while using my db browser to watch db state progress appropriately?
If not - which is what I'm guessing - I'd happily settle for a way to examine the database contents after an integration test. My integration tests work just fine. It's just that after they complete I'd like to be able to pop open my db browser and poke around, verifying various values to ensure to my satisfaction things in the db are as they should be.
Another possible solution that would work for me is if there was something within my integration tests that could access db values so I could verify things programmatically. I have in mind something like how assigns give you access to instance variables within your integration tests that you can then do 'asserts' calls on.
And, of course, please let me know if I'm way off track and there's a "best practice" for this type of thing that I've missed.
I'm using Rails 4.2.0 and Ruby 2.2.2p95
While Minitest doesn't have a way to do the first option you mentioned, you might checkout Watir as a means of (partially) automating tests so you leave off at a certain point with the browser still open and continue manually while watching what's going on in the DB.
However, since the second option you mentioned is possible with Minitest (and will save you even more time by being fully automated) I'd highly recommend it. See the Ruby on Rails Tutorial 3rd Edition by Michael Hartl for some examples (you might find the whole thing helpful, but here's a section that shows a test much like what you are looking for: Section 7.4.4.)
My friend has setting up a database for a Ragnarok Online server, and he wants me to code the relative website, which is going to use some of that data (and obviously, i'll have to add tables for the news system, website accounts, etc). Since i'm learning RoR i was going to do it that way.
I have a few "best practice" questions related to this :
Should I create a different database for the website, since it's going to have its particular data alongside the game data ? (i already have a few clues to link multiple databases with Rails, but that seems too much of a hassle for what it is).
If not, do i have to create Model/Controller for each of the tables composing the database, despite the fact that i'm not going to use 90% of it ? Or just the ones that i need ?
An example of this problem : the game database has its own "user" table, but i have to have another "user" table for the website, and do some Joins between those two. So, what's the best practice here ?
Uhm, best practice is not making your own user table. This will cause you much pain. Best practice? Use an API. Expose the game's database in some way to your website, and fetch that info with external requests in your web application.
The reason why making a second user table is a hassle:
1) You'll constantly have to update it, pulling data from the original
to keep it up-to-date.
And I mean furthermore, you're gonna have to create a CRON job or something pulling data from that original table to keep it up to date. Yuck. Also what if that CRON job makes a mistake? (It will)
2) It's almost inevitable that there will be inconsistencies if two
separate tables are maintained. Are you sure your web application is
really fail-proof?
Update:
What you're gonna need is essentially a second Rails application that acts as a REST API for that database. For a good idea of what REST is, I'd read through this to get you started: http://tomayko.com/writings/rest-to-my-wife
Once you have a good understanding of that, start making your app, and test if it's working by using tools like cURL to send requests to your API.
Once you have that done, I'd take a look into the Ruby rest-client gem like Nobita mentioned. This is what you're going to use from your web application to request information from your API application.
Just let me note, I think this would be a terrible first Rails project, unless you're already really well versed in other web development tools, preferably MVC frameworks.
We are planning to make a "large" website for I'd say 5000 up to many more users. We think of putting in lots of real time functionality, where data changes instantly propagate to all connected clients. New frameworks like Meteor and DerbyJS look really promising for this kind of stuff.
Now, I wonder if it is possible to do typical backend stuff like sending (bulk) emails, cleaning up the database, generating pdfs, etc. with those new frameworks. And in a way that is productive and doesn't suck. I also wonder how difficult it is to create complex forms with them. I got used to the convenient Rails view helpers and Ruby gems to handle those kind of things.
Meteor and DerbyJS are both quite new, so I do expect lots of functionality will be added in the near future. However, I also wonder if it might be a good idea to combine those frameworks with a "traditional" Rails app, that serves up certain complex pages which do not need realtime updates. And/or with a Rails or Sinatra app that provides an API to do the heavy backend processing. Those Rails apps could then access the same databases then the Meteor/DerbyJS app. Anyone thinks this is a good idea? Or rather not? Why?
It would be nice if anyone with sufficient experience with those new "single page app realtime" frameworks could comment on this. Where are they heading towards? Will they be able to handle "complete" web apps with authentication and backend processing? Will it be as productive/convenient to program with them as with Rails? Well, I guess no one can know that for sure yet ;-) Well, any thoughts, guesses and ideas are welcome!
For things like sending bulk emails and generating PDFs, Derby let's you simply use normal Node.js modules. npm now has over 10,000 packages, so there are packages for most things you might want to do on the server. Derby doesn't control your server, and it works on top of any normal Express server. You should probably stick with Node.js code as much as possible and not use Rails along with Derby. That is not to say that you can't send messages to a separate Rails app, but since you already have to have a Node.js app running to host Derby, you might as well use it for stuff like this.
To communicate with such server-side code, you can use Derby's model events. We are still exploring how this kind of code works and we don't have a lot of examples, but it is something that we will have a clear story around. We are building an app ourselves that communicates with an email server, so we should have some real experience with this pretty soon.
You can also just use a normal AJAX request or send a message over Socket.IO manually if you don't want to use the Derby model to do this kind of communication. You are free to make your own server-side only routes with Express along with your Derby app routes. We think it is nice to have this kind of flexibility in case there are any use cases that we didn't properly anticipate with the framework.
As far as creating forms goes, Derby has a very powerful templating system, and I am working on making it a lot better still. We are working on a new UI components feature that will make it possible to build libraries of self-contained UI widgets that can simply be dropped into a Derby app while still playing nicely with automatic view-model bindings and data syncing. Once this feature is completed, I think form component libraries will be written rather quickly.
We do expect to include all of the features needed for a normal app, much like Rails does. It won't look like Rails or work like Rails, but it will be similarly feature complete eventually.
For backend tasks (such as sending emails, cleaning up the database, generating pdfs) it's better to use resque or sidekiq
Now, I wonder if it is possible to do typical backend stuff like
sending (bulk) emails, cleaning up the database, generating pdfs, etc.
with those new frameworks. And in a way that is productive and doesn't
suck. I also wonder how difficult it is to create complex forms with
them. I got used to the convenient Rails view helpers and Ruby gems to
handle those kind of things.
Also, my question is not only about background jobs, but also about stuff one can might do during a request, like generating a pdf, or simply rendering complex views with rails helpers or code from gems. –
You're mixing metaphors here - a single page app is just a site where the content is loaded without doing a full page reload, be that a front end in pure js or you could use normal html and pjax.
The kind of things you are describing would be done in a background task regardless of the fornt-end framework you used. But +1 for sidekiq if you're using ruby.
As for notifying all the other users of things that have changed, you can look into using http://pusher.com or http://pubnub.com if you don't want to maintain a websocket server.
Firstly let me mention that I'm new to web-frameworks.
I have to write my first web-app for a Uni project. I spent two weeks learning Grails and Django. Started working with Rails yesterday and loved it. So I've decided to go with it and discard my work in the other frameworks.
About the app
It's supposed to be a Twitter app that utilizes Twitter's Streaming API to record tweets which match a set of specified filters. (I'm going to use the Tweetstream gem which takes care of connecting to Twitter and capturing matching tweets).
The app's web interface should have the following functionality -
Creating new requests The user inputs a set of filter parameters (keywords to track) & URL/username/password of an existing PostgreSQL or MySQL database.
When a request is created, the web-app spawns a background ruby process. This process connects to Twitter via the Tweetstream gem. It also connects to the database specified by the user to stores received tweets.
View/terminate of existing requests
The user should be able to see a list of requests that are running as background processes by visiting a URL such as /listRequests.
See further details about a process/terminate the process
The user should be able to go to URL such as /requests/1/detail to view some details (e.g how long request has been running, number of tweets captured, etc). The user should also be able to terminate the process.
My inexperience is showing as I'm unable to comprehend -
what my models should be (maybe Request should be a model. Tweet doesn't need to be a model as it's not being stored locally)
how I'm going to connect to remote databases.
how I can create background processes (backgroundrb??) and associate them with request objects so that I can terminate then when the user asks.
At the end of the day, I've got to build this myself, so I'm not asking for you to design this for me. But some pointers in the right direction would be extremely helpful and appreciated!
Thanks!
Hmm.
Since the web app is just a thin wrapper around the heavy-lifting processes, it might be more appropriate to just use something like Sinatra here. Rails is a big framework that pulls in lots of stuff that you won't need for this project, even though it will work.
Does the "background process" requirement here strictly mean a separate process, or does it just mean concurrency? TweetStream uses the EventMachine gem to handle updates as they come, which uses a separate thread for each connection. It would be quite possible to spawn the TweetStream clients from a simple Sinatra web app, keep them in a big array, have them all run concurrently with no trouble, and simply run stop on a given client when you want it to stop. No need for a database or anything.
I'm not sure exactly what your prof is looking for you to do here, but MVC doesn't really fit. It's better to work with the requirements than to mush it into a design pattern that doesn't match it :/
Even so, I <3 Rails! Definitely get on that when you're working primarily with objects being represented in a database :)
Quite a project. Most of what will be challenging is not related to rails itself, but rather the integration with background processes. backgroundrb is a bit out of fashion. The last commit on the main github project is over a year ago, so it's likely not up to snuff for Rails 3. Search around and evaluate your options. Resque is popular, but I'm not sure if your real-time needs match with its queue-based structure.
As for your app, I see only a single model, but don't call it request. That's a reserved name in rails. Perhaps a Search model, or something along that line.
Connecting to different databases is straight forward but will require direct configuration of your ActiveRecord class during operation rather than using database.yml.