There is still some Objective-C developmen You Have Unlocked All the Answers! You Have Unsubscribed from All Communications! System Design. NET Core NET Android Angular AngularJS C CSS Design Patterns DevOps Entity Framework Flutter Git Golang GraphQL HTML5 Ionic Java JavaScript Kotlin LINQ Laravel What id the difference between Static and Dynamic Scaffolding? What is ORM Rails?
ORM stands for Object-Relationship-Model, it means that your Classes are mapped to table in the database and Objects are directly mapped to the rows in the table. Does Ruby supports Multiple Inheritance?
No, Ruby supports only single Inheritance. Is there any alternative of Multiple inheritance in Ruby? Please Explain. Yes, Ruby offers a very neat alternative concept called mixin. Modules can be imported inside other class using mixin. They are then mixed-in with the class in which they are imported. What is Bundler?
Bundler is a new concept introduced in Rails3, which helps to you manage your gems for the application. After specifying gems in your Gemfile, you need to do a bundle install. If the gem is available in the system, bundle will use that else it will pick up from the rubygems. What are class variables?
How do you define them? Class variables are created using the prefix to denote the variable as class level. It works just like any other variable, however in the case of inheritance it works more like a static variable that is accessed across all variable instances. Does Ruby support constructors? How are they declared? Constructors are supported in Ruby.
They are declared as the method initialize, shown below. The initialize method gets called automatically when Class. What is the purpose of Yield in Ruby? Ruby provides a yield statement that eases the creation of iterators. The first thing I noticed was that its behavior is different from the C yield statement which I knew from before.
Whereas, render is a method used to create the content. Whereas, render only works in case the controller is being set up properly with the variables that needs to be rendered.
Whereas, render method renders a page and generate a code of Ruby Class Variables Class variables begin with and must be initialized before they can be used in method definitions. Referencing an uninitialized class variable produces an error.
Class variables are shared among descendants of the class or module in which the class variables are defined. Overriding class variables produce warnings with the -w option. Here is an example showing usage of class variable:! This will produce following result: Total number of customers: 1 Total number of customers: 2 Ruby Instance Variables Instance variables begin with. Uninitialized instance variables have the value nil and produce warnings with the -w option.
Here is an example showing usage of Instance Variables. Uninitialized global variables have the value nil and produce warnings with the -w option. Assignment to global variables alters global status. It is not recommended to use global variables.
They make programs cryptic. Here is an example showing usage of global variable. Global variable in Class1 is 10 Global variable in Class2 is 10 What is Gemfile and Gemfile. The Gemfile is where you specify which gems you want to use, and lets you specify which versions. The Gemfile. Running different versions on different machines could lead to broken tests, etc. Get more Explanations on Gem file here.
What is the difference between puts and print? This association indicates that each instance of the model has zero or more instances of another model. How to use sql db or mysql db without defining it in the database.
How you run your Rails application without creating databases? You can run your application by uncommenting the line in environment. What are the servers supported by ruby on rails? Can we use two databases into a single application? Yes, Definitely. Symbol belongs to the category of immutable objects whereas Strings are considered as mutable objects.
It follows the standard ORM model as. Ajax powered web page retrieves the web page from the server which is new or changed unlike other web-page where you have to refresh the page to get the latest information. Rails Migration enables Ruby to make changes to the database schema, making it possible to use a version control system to leave things synchronized with the actual code. When migrating to a new version, self. The Rails controller is the logical center of the application.
It faciliates the interaction between the users, views, and the model. It also performs other activities like. It means that the value stored for a symbol key cannot be retrieved using the equivalent string. CSRF is a form of attack where hacker submits a page request on your behalf to a different website, causing damage or revealing your sensitive data. CSRF token is given as a hidden field in every form created using Rails form builders. Mixin in Ruby offers an alternative to multiple inheritances, using mixin modules can be imported inside other class.
In Rails, Rake is used for normal administration tasks like migrating the database through scripts, loading a schema into the database, etc.
It is sometimes used to define the JavaScript, Prototype and helpers provided by Rails. A perfect example of Polymorphic Association is a social site where users can comment on anywhere whether it is a videos, photos, link, status updates etc. This might make Rails not useful for other programmers.
Some of the features that Rails does not support include. Overriding class variables produce warnings with the -w option. Here is an example showing usage of class variable:! This will produce following result: Total number of customers: 1 Total number of customers: 2 Ruby Instance Variables Instance variables begin with.
Uninitialized instance variables have the value nil and produce warnings with the -w option. Here is an example showing usage of Instance Variables. Uninitialized global variables have the value nil and produce warnings with the -w option.
Assignment to global variables alters global status. It is not recommended to use global variables. They make programs cryptic. Here is an example showing usage of global variable. Global variable in Class1 is 10 Global variable in Class2 is 10 What is Gemfile and Gemfile. The Gemfile is where you specify which gems you want to use, and lets you specify which versions.
The Gemfile. Running different versions on different machines could lead to broken tests, etc. Get more Explanations on Gem file here.
What is the difference between puts and print? This association indicates that each instance of the model has zero or more instances of another model. How to use sql db or mysql db without defining it in the database. How you run your Rails application without creating databases? You can run your application by uncommenting the line in environment. What are the servers supported by ruby on rails? Can we use two databases into a single application?
Yes, Definitely. After installing this gem, just add this line at bottom of your environment. What is scope?
Scopes are nothing more than SQL scope fragments. By using these fragments one can cut down on having to write long queries each time you access content. Can you give an example of a class that should be inside the lib folder? Modules are often placed in the lib folder. Where should you put code that is supposed to run when your application launches?
What deployment tool do you use? Capistrano is a popular deployment tool, it allows developers to push code from their desktop to the servers. What is a filter? When it is called? What is the difference between a plugin and a gem? A gem is just ruby code. Rails, rake, json, rspec — are all examples of gems. Plugin is also ruby code but it is installed in the application folder and only available for that specific application.
Sitemap-generator, etc. In general, since Rails works well with gems you will find that you would be mostly integrating with gem files and not plugins in general. Most developers release their libraries as gems. How many types of callbacks available in ROR? What is request. A request. How to serialize data with YAML? YAML is a straight forward machine parsable data serialization format, designed for human readability and interaction with scripting language such as Perl and Python.
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