I am trying to write a very simple rails backend backed up with a mysql database. It's very simple, I have two tables, one is the users table, tweets table, and a time for each tweet. Basically besides just an API, I would like to write a scheduler for posting the tweets at a specific time in the database. This is what confuses me.. how do I write a loop in the background that always checks the current time if there's any tweet that needs to be posted?
Any recommendation/guidelines in achieving this would be helpful.
You need a background job management.
Periodically, you will check if there is anything to do and eventually do it.
Please check this relevant SO question.
Here are some other pointers:
http://4loc.wordpress.com/2010/03/10/background-jobs-in-ruby-on-rails/
https://github.com/tobi/delayed_job
https://github.com/javan/whenever/
Related
does anyone know if it is possible to create relationships in the dashboard of parse?
I'm running the bitnami parse api 1.0.18 through aws ec2 and can't see anyway of doing it and the documentations only says you can do it through code. i want to have these set up in the background as the user won't write to them, probably just download some data and images.
i could just go and create a whole heap of tables with unique identifiers but this seems a bit of a dumb work around.
I strongly suggest you look into Cloud code. This is one of the reason why cloud code works so well! Simple to setup and little bit of javascript you'll be on your way.
http://parseplatform.github.io/docs/cloudcode/guide/
If its something that needs to happen before the insert, look at the beforeSave method.
I am not sure what is better perfomance whise so I ask you guys.
The problem is following:
I have a system where each User gets a certain amount of credit for certain events. So I gave my User an attribute named creditscore that gets altered on those events. Everything works well. But now I want the user to actually see what he did when and how much credit he got for this.
What would be better here:
Saving the whole history in a text attribute and add lines for each event
or
writing an extra model associated with the user and create an instance for every event.
or
or
something way different?
Since there are several events per user per day it would be either a huge text or a huge amount of instances. What would be better looking at website performance.
You absolutely do NOT want to store the history in a text attribute. Management of this will be a nightmare as will querying the data.
You could create a CreditEvent model and store the individual events in there. That would work fine.
However, before you start, check rubygems.org and ruby-toolbox.com to see if someone has already done the hard work. I know of at least one gem that seems to do exactly what you want to do:
https://github.com/merit-gem/merit
I have an application that makes API requests to salesforce using restforce.
Specifically the application finds a contact object, returns IDs for all related objects and then pulls the full record for every related object based on their ID.
This takes a long time for two reasons:
There are a lot of request to an external API, usually takes a few fractions of a second for each to reply and for some there can be +500 individual requests.
There is often a large amount of data being pulled back via each request.
All requests currently fall within the salesforce rest API limits but I'm getting timeout errors from my development server as it can take 5+ minutes for some of these requests to process.
Rails 4.2 - How best to handle this?
My question is how do I best get rails to handle this?
I can fire the API requests either from the controller (which definitely violates the skinny controllers) or from the view (via helper methods, which seems like a dodgy hack).
Ideally I'd like to get it running in a background job, but i'm unsure if I can just include all the authentication and other methods in a job in the same way I can include helper methods?
Even if I could get it to work in a background job, I'm unsure what best practice might be for the user experience. Ideally I'd like to route them to a page telling them to "hang tight, go get a coffee" with a progress bar, and then auto route them to the final page once the request is complete...
But I'm unsure how to generate a temporary display until a job has been completed?
Could anyone recommend any gems or strategies that might help me digest this problem?
You should definitely use a background job for this.
Give a database object to the job, which it will update to signal that is has finished, and maybe from time to time to indicate progress.
On the user side, simply tell them that the background job is working, with eventually a progress indicator, and display the result once the database object giving to the job tells you it's ready.
I am looking for solution of logging data changes for public API.
There is a need to tell client app which tables form db has changed and need to be synchronised since the app synchronised last time and also need to be for specific brand and country.
Current Solution:
Version table with class_names of models which is touched from every model on create, delete, touch and save action.
When we are touching version for specific model we also look at the reflected associations and touch them too.
Version model is scoped to brand and country
REST API is responding to a request that includes last_sync_at:timestamp, brand and country
Rails look at Version with given attributes and return class_names of models which were changed since lans_sync_at timestamp.
This solution works but the problem is performance and is also hard to maintenance.
UPDATE 1:
Maybe the simple question is.
What is the best practice how to find out and tell frontend apps when and what needs to be synchronized. In terms of whole concept.
Conditions:
Front end apps needs to download only their own content changes not whole dataset.
Does not invoked synchronization when application from different country or brand needs to be synchronized.
Thank you.
I think that the best solution would be to use redis (or some other key-value store) and save your information there. Writing to redis is much faster than any sql db. You can write some service class that would save the data like:
RegisterTableUpdate.set(table_name, country_id, brand_id, timestamp)
Such call would save given timestamp under key that could look like i.e. table-update-1-1-users, where first number is country id, second number is brand id, followed by table name (or you could use country and brand names if needed). If you would like to find out which tables have changed you would just need to find redis keys with query "table-update-1-1-*", iterate through them and check which are newer than timestamp sent through api.
It is worth to rmember that redis is not as reliable as sql databases. Its reliability depends on configuration so you might want to read redis guidelines and decide if you would like to go for it.
You can take advantage of the fact that ActiveModel automatically logs every time it updates a table row (the 'Updated at' column)
When checking what needs to be updated, select the objects you are interested in and compare their 'Updated at' with the timestamp from the client app
The advantage of this approach is that you don't need to keep an additional table that lists all the updates on models, which should speed things up for the API users and be easier to maintain.
The disadvantage is that you cannot see the changes in data over time, you only know that a change occurred and you can access the latest version. If you need to track changes in data over time efficiently, than I'm afraid you'll have to rework things from the top.
(read last part - this is what you are interested in)
I would recommend that you use the decorator design pattern for changing the client queries. So the client sends a query of what he wants and the server decides what to give him based on the client's last update.
so:
the client sends a query that includes the time it last synched
the server sees the query and takes into account the client's nature (device-country)
the server decorates (changes accordingly) the query to request from the DB only the relevant data, and if that is not possible:
after the data are returned from the database manager they are trimmed to be relevant to where they are going
returns to the client all the new stuff that the client cares about.
I assume that you have a time entered field on your DB entries.
In that case the "decoration" of the query (abstractly) would be just to add something like a "WHERE" clause in your query and state you want data entered after the last update.
Finally, if you want that to be done for many devices/locales/whatever implement a decorator for the query and the result of the query and serve them to your clients as they should be served. (Keep in mind that in contrast with a subclassing approach you will only have to implement one decorator for each device/locale/whatever - not for all combinations!
Hope this helped!
What is the simplest way how to check if user is online and display list of online users?
The only way I can think of is some periodic polling server to update last action timestamp, and when last timestamp is more than xx ago, user is considered to be offline. But it doesn't seem like too eficient solution.
Authlogic can do this by default, and is a great authentication system that is very powerful. I would suggest migrating your current authentication system over to it (maybe a days worth of work, depending how customized your system is).
If you can't (or simply don't want to) move your application over to Authlogic, you can check out the source code at the link above, as well as an example project here.
You could potentially check the session time, if you use database session store. When the updated_at extends past a certain time, assume the user is no longer active. This could be problematic as well, however.
Being honest, it's a somewhat difficult scenario to tell the active number of users without some form of periodic server polling. Your thought is not a bad one.
We can list the online users using active record session store, please see this github app https://github.com/mohanraj-ramanujam/online-users