I'm a bit of a Rails beginner, so I'm sorry if this question is easy. I'm wondering how I am supposed to modify the Rails database as a developer without letting users of the site modify data.
More information:
Let's say I am trying to create a website that lists books along with their information. I want users to be able to see these books, but not add/delete them. As a developer, I want a way to add books without using the command line (hard to edit mistakes). What's the easiest way for me to do this? Would there be any differences between the development database and a live hosted one?
I think there are a few approaches to do this.
different user roles. This technically breaks the rule of without letting users of the site modify data, but being able to differentiate between normal and admin users means you can limit who actually can add data into the database. I used cancancan as a way to authorize requests but I know there are others.
I agree doing it using the command line isn't ideal, but rails do support rake tasks. You can create a task that will handle most of the logic and all you need to do is something like
rake create_book["name here"]
This will make the process less error-prone.
Create data using rails migrations. Rails can generate the skeleton file for you, and you just ran any ActiveRecord methods. However, the main purpose of migration is to update the database schema, but they can seed the database as well. here's the example from the dcos
Would there be any differences between the development database and a live-hosted one?
Yea, they should be totally separate database instances. You don't want to have your development database be the same as the live one. This would cause major problems. Rails have a concept of environments where you can use different configurations, so you can pick and choose what database URL to use.
like #davidhu said here The best approach really is the use of authorization. If only admin can see a page to CRUD the books then you don't have to worry about normal users doing same plus it makes it easy for you as the admin to make changes or add to the collection. Add the gem (or reinvent the wheel) then Rails will take care of the rest for you.
Related
I know there are some questions to this effect already on StackOverflow, but they tend to be pretty outdated and don't adequately address how migrations are supposed to work in the following scenario, which should be fairly common:
You have some kind of application, implemented in Rails.
You have some kind of admin application for your data, and it is a separate application implemented in Rails.
Both applications operate on the same database and models.
My question is: what is the best way to factor our models such that both of these applications don't have to duplicate model code?
We are concerned with the following:
For the shared models, where should database migrations live?
What if each individual application wishes to add additional models on top of shared models? Where do these migrations live?
What is the best way to move existing migrations into the proposed shared migration scheme?
Thanks.
I don't know if this is THE approach, and would love to see other ideas, but what we do in one of our products that matches this model:
For the shared models, where should database migrations live?
We keep all of our migrations under the admin system. You don't need them to exist twice, so that's where they go.
What if each individual application wishes to add additional models on top of shared models? Where do these migrations live?
We share all models. It might only be relevant to one application at the moment, say - a favourited_items concept might only matter to the end user. But at a later date the admin might want to know what items are most frequently favourited.
Secondly, if you want to investigate anything via console, it's really quite helpful if you don't need to visit separate applications because they don't both have models for every table.
Functionality in shared models that differs per application detects the rails environment variable, which we have extended to include more context. E.g.: if Rails.env == 'admin_production'
What is the best way to move existing migrations into the proposed shared migration scheme?
Again, migrations should only ever exist once, and the shared database knows which have already been run, so unless you're renaming the migrates you just need to pick a location and move the files.
I am new to ruby on rails and I am working on a web application written by ruby on rails. It has more than 10 models and I need to add some new attributes to some of the models as well as new methods and views. I also will need to remove or enhance some of the functionality. I know that I would need to generate new migrations and from there add/remove new columns. Then in controllers, add/modify methods, and update the views.
I wanted to know what would be the best steps (and in which order) for doing the above tasks. Also, do I need to change other files in folders like test or any other folder? What things should I consider to minimize the troubles later?
Thanks in Advance.
Since you are new to rails, the first thing you should do is to read through the getting started guide. This will help you understand the fundamentals of the rails framework and the application you inherited. After that, there are several other guides worth reading (from the same site) that may be directly applicable to the work you are doing.
Another incredibly helpful resource is railscasts. Some of these are outdated, but they are still a great starting place and can help introduce you to both new, powerful gems and rails techniques to get the work done faster and better.
As to your specific question, rails is built on an MVC architecture (meaning Model Views Controllers). It is in your best interest to try and follow this practice whenever possible. Reading up on this will clarify some of your questions as well.
When you run a migration, you will be modifying your database. The changes are viewable in the database schema (which should never be modified by hand, always modify it through migrations). This will add attributes to your models whose table you modified. In the controllers, you will add logic to deal with all of these things and the views will present the data to your users (or allow users to enter data). Asking which order is best is probably rather opinion based, but I would say you should modify the tables (run needed migrations) first. This way you can then generate the logic to deal with the new attributes. I would then create the controller logic and finally the views.
You also ask what other files need to be changed. This is heavily dependent on your system. At a base level, you should definitely be writing tests to support the logic you are generating (and many developers will advocate that you should do this before you write the other logic, a process called Test Driven Development).
TL;DR: Read the guides, work through a basic tutorial, and watch some Railscasts. This should get you up to speed on the process and best practices that go along with rails development.
Suppose that you wanted to create two apps, both on Rails, but they share the same set of models. I'm certain I could 'hack' something together, that would probably work, but I'm curious what the best approach is.
Oh, and if you're curious about motivation: I want to freely restart the admin processes without disturbing the user processes. Also there is a bit of extra security not sharing the same session.
You could create a gem or engine with your models in the lib directory. Then they could easily be used by more than one Rails app. Google "rails engines" and you should get some ideas. If all you're doing is models though, a fullblown engine may be overkill and you can get by with a simple gem.
We have an admin application used to manage member data and it was built in 2.1, has been running for about a year. Now that all inputs and data massage is done, our client wants to start building member site, members will have access to data the administrators have been inputting.
Here's the question, should we start a new Rails app hooked to the same admin database or should we create a new Rails app in different db with master-slave settings? The good thing about creating a new Rails app is obviously taking advantage of the new version, which we like. Or ..maybe just build the member site in the same admin app?
THanks,
Why don't you want to build the member site in the same admin app? Too much legacy?
You can use the same database but the problem is you will have to enforce any conditions you have in your models directly in your database (mandatory fields, model relationship and so on).
And I can see a lot of duplication code happening between the two apps. At least for the models. Which is really wrong :(
I don't recommend making two separate applications but It is hard to answer without looking at your app and without knowing more details.
Or build a new app using a copy of the existing database?
There's no reason the two applications cannot share the same database.
However, there's probably a number of reasons why they shouldn't. But, the only way you're going to figure those out are by going through the changelog of ActiveRecord's database adaptors.
It's an application that we use internally at the office that I would like to offer as a hosted service for anyone.
How can I do that without making major code changes?
The first thing that occurs to me is to have the app select which database to connect to based on the domain.
So each instance of the app would have its own database, but all instances would share the same code.
The only changes required to the code would be the database selection.
Is this approach maintainable? I've heard wordpress.com does this and that it offers a couple of advantages. I'm mainly looking to do it this way to avoid have to scope my entire set of database queries to a certain site within the same database.
Thanks!
The simplest way to do this is to clone the application, and create another server instance to handle it. This actually the way I handle multiple wordpress blogs on my server
Pro:
This process can be streamlined into a utility script.
Can be easily maintained if symlinks are used for the common code. IE: Everything but branding and some of the things in the config directory.
Cons:
- If you're using passenger it will require an apache restart for each new instance.
- Same if you're using Apache to route subdomains on different virtual hosts to different mongrel clusters.
However the better way comes from the question: Rails - Separate Database Per Subdomain
The method in the accepted answer is much more robust. It might require more changes than you're looking for, but it has all the benefits without the drawbacks of any other methods. Each new instance requires a new entry in the master database with the table name and other instance specific information. You'll also want custom rake task to build the database for each new instance.
I would suggest switching the database connection and adding a view_path based on the domain, I have posted code in this question.
I hope this helps!
I wouldn't do this with multiple databases as you mentioned. Keeping all your schemas/migrations in sync with all the db's could become painful.
I would look into simply making it a multi-tenant app where you have some sort of "Account" model and then all your existing models are scoped to it ... in other words, if this was a blog app, your Account has_many :posts, etc.
With this approach, you can identify accounts by subdomain ... have people choose their subdomain when they create an account and go from there.
It's pretty straightforward to do. If you need add billing into the mix, you might look at the SaaS Railskit (which handles all the signup and subdomain stuff) or Chargify.
You can also identify accounts Twitter-style ... with http://myapp.com/someuser