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100 Ruby on Rails Interview Questions: Answers and Tips for Developers 30/03/2023 ~ Views: 1087
  1. What is Ruby on Rails?
    Answer: Ruby on Rails is a web application framework written in the Ruby programming language that follows the Model-View-Controller (MVC) architectural pattern.
  2. What is the difference between a gem and a plugin?
    Answer: A gem is a library or package in Ruby that can be installed and used in a project, while a plugin is a piece of code that extends the functionality of an application.
  3. What are the components of Rails?
    Answer: The components of Rails are the Model, View, Controller, and Routing.
  4. Explain the concept of Convention over Configuration in Rails.
    Answer: Convention over Configuration is a principle in Rails that suggests that the developer should follow certain conventions while developing the application, and Rails will automatically configure the rest of the application accordingly.
  5. What is a migration in Rails?
    Answer: A migration is a way to modify the database schema using Ruby code. It allows you to change the database schema without having to manually update the SQL code.
  6. What are the various types of associations in Rails?
    Answer: The various types of associations in Rails are has_one, has_many, belongs_to, and has_and_belongs_to_many.
  7. What is the purpose of before_filter in Rails?
    Answer: before_filter is a callback method that is used to execute some code before a controller action is called.
  8. What is the difference between include and extend in Ruby?
    Answer: include is used to add the functionality of a module to an instance of a class, while extend is used to add the functionality of a module to the class itself.
  9. What is the purpose of attr_accessor in Ruby?
    Answer: attr_accessor is a Ruby method that creates getter and setter methods for a class attribute.
  10. What is the difference between HTTP GET and POST requests?
    Answer: HTTP GET requests are used to retrieve data from a server, while HTTP POST requests are used to send data to a server.
  11. What is the purpose of the asset pipeline in Rails?
    Answer: The asset pipeline is a way to manage and organize assets such as JavaScript, CSS, and images in a Rails application.
  12. What is RESTful routing in Rails?
    Answer: RESTful routing is a way to define routes in a Rails application that conform to the REST architectural style.
  13. What is the purpose of the yield keyword in Rails layouts?
    Answer: The yield keyword in a Rails layout is used to specify where the content of a view should be placed in the layout.
  14. What is a rake task in Rails?
    Answer: A rake task is a script that is used to automate repetitive tasks in a Rails application.
  15. What is a serializer in Rails?
    Answer: A serializer is a way to convert objects in a Rails application into a format that can be easily consumed by other applications or services.
  16. What is the purpose of the Rails console?
    Answer: The Rails console is a command-line tool that allows you to interact with a Rails application and test code snippets.
  17. What is the difference between a scope and a class method in Rails?
    Answer: A scope is a predefined query that can be chained with other queries, while a class method is a method that can be called on a model without a specific scope.
  18. What is the purpose of the belongs_to association in Rails?
    Answer: The belongs_to association in Rails is used to define a one-to-one or many-to-one relationship between two database tables. It is typically used to establish a relationship between a child table and a parent table, where the child table has a foreign key that references the parent table's primary key.
  19. What is the purpose of the has_many association in Rails?
    Answer: The has_many association in Rails is used to define a one-to-many relationship between two database tables. It is typically used to establish a relationship between a parent table and a child table, where the parent table's primary key is referenced as a foreign key in the child table.
  20. What is the purpose of the has_and_belongs_to_many association in Rails?
    Answer: The has_and_belongs_to_many association in Rails is used to define a many-to-many relationship between two database tables. It is typically used to establish a relationship between two tables where each record in one table can be associated with multiple records in the other table, and vice versa.
  21. What is the purpose of the validates method in Rails?
    Answer: The validates method in Rails is used to define validation rules for a model's attributes. It allows developers to specify what data is valid for a particular attribute and what data is not. Common validation rules include presence, length, numericality, and format.
  22. What is the purpose of the has_secure_password method in Rails?
    Answer: The has_secure_password method in Rails is used to add authentication functionality to a model. It automatically adds password hashing and salting, as well as methods for password validation and authentication. It requires that the model has a password_digest attribute in the database.
  23. What is the purpose of the params hash in Rails?
    Answer: The params hash in Rails is a way to access data submitted in a request, typically from a form or URL parameters. It allows developers to easily access and manipulate this data within their controller actions and other parts of the application.
  24. What is the purpose of the Gemfile in a Rails application?
    Answer: The Gemfile is a file that is used to specify the gems that a Rails application depends on.
  25. What is the difference between a local variable and an instance variable in Ruby?
    Answer: A local variable is a variable that is scoped to a particular method or block, while an instance variable is a variable that is scoped to a particular instance of a class.
  26. What is the purpose of the strong parameters feature in Rails?
    Answer: The strong parameters feature in Rails is a way to ensure that only certain parameters can be passed into a controller action, which helps to prevent security vulnerabilities such as SQL injection attacks.
  27. What is the purpose of the flash hash in Rails?
    Answer: The flash hash in Rails is a way to store temporary data that is only available for one request and is typically used to display flash messages to the user.
  28. What is the difference between a hash and an array in Ruby?
    Answer: An array is an ordered collection of elements, while a hash is an unordered collection of key-value pairs.
  29. What is the purpose of the application layout file in a Rails application?
    Answer: The application layout file in a Rails application is a template that is used to define the overall layout of the application.
  30. What is the purpose of the ActiveRecord class in Rails?
    Answer: The ActiveRecord class in Rails is a way to interact with a database using object-oriented programming concepts.
  31. What is the purpose of the form_for helper in Rails?
    Answer: The form_for helper in Rails is a way to generate HTML forms that are tied to a particular model and can be used to create, update, or delete records.
  32. What is the purpose of the sanitize method in Rails?
    Answer: The sanitize method in Rails is a way to remove any potentially harmful HTML tags or attributes from a string.
  33. What is the difference between a has_many :through and a has_and_belongs_to_many association in Rails?
    Answer: A has_many :through association requires the use of an intermediate model, while a has_and_belongs_to_many association does not.
  34. What is the purpose of the gemspec file in a Ruby gem?
    Answer: The gemspec file in a Ruby gem is a file that is used to specify information about the gem, such as its name, version, dependencies, and files.
  35. What is the purpose of the require keyword in Ruby?
    Answer: The require keyword in Ruby is used to load a file or library into the current Ruby program.
  36. What is the difference between a private and a protected method in Ruby?
    Answer: A private method can only be called from within the same object, while a protected method can be called from within the same object or any descendant objects.
  37. What is the purpose of the root route in a Rails application?
    Answer: The root route in a Rails application is the default route that is used when a user visits the root URL of the application.
  38. What is the difference between a string and a symbol in Ruby?
    Answer: A string is a collection of characters, while a symbol is a unique identifier that is used to represent a value.
  39. What is the purpose of the gemfile.lock file in a Rails application?
    Answer: The gemfile.lock file in a Rails application is a file that is generated automatically and is used to specify the exact versions of the gems that a Rails application is using.
  40. What is the purpose of the yield_self method in Ruby?
    Answer: The yield_self method in Ruby is a way to pass the result of a block as an argument to a method call.
  41. What is the purpose of the flash.now hash in Rails?
    Answer: The flash.now hash in Rails is a way to store temporary data that is only available for the current request and is typically used to display flash messages to the user.
  42. What is the purpose of the respond_to method in Rails?
    Answer: The respond_to method in Rails is a way to specify the format of the response that should be returned by a controller action.
  43. What is the purpose of the validates method in Rails?
    Answer: The validates method in Rails is a way to define validations for model attributes, which are used to ensure that the data stored in the database is valid.
  44. What is the purpose of the before_action callback in Rails?
    Answer: The before_action callback in Rails is a way to specify a method that should be called before a controller action is executed, which can be used to perform common tasks such as setting up authentication or authorization.
  45. What is the difference between a class method and an instance method in Ruby?
    Answer: A class method is a method that can be called on a class itself, while an instance method is a method that can only be called on an instance of a class.
  46. What is the purpose of the has_secure_password method in Rails?
    Answer: The has_secure_password method in Rails is a way to add password encryption and authentication functionality to a Rails model.
  47. What is the difference between a block and a lambda in Ruby?
    Answer: A block is a piece of code that can be passed to a method, while a lambda is a type of anonymous function that can be assigned to a variable and called like a method.
  48. What is the purpose of the collection_select helper in Rails?
    Answer: The collection_select helper in Rails is a way to generate a dropdown list that is populated with data from a database table.
  49. What is the purpose of the find_by method in Rails?
    Answer: The find_by method in Rails is a way to find a record in a database based on a specific attribute value.
  50. What is the purpose of the attr_accessor method in Ruby?
    Answer: The attr_accessor method in Ruby is a way to define getter and setter methods for a class attribute.
  51. What is the purpose of the belongs_to association in Rails?
    Answer: The belongs_to association in Rails is a way to define a one-to-one or many-to-one relationship between two models.
  52. What is the purpose of the has_one association in Rails?
    Answer: The has_one association in Rails is a way to define a one-to-one relationship between two models.
  53. What is the purpose of the belongs_to_many association in Rails?
    Answer: The belongs_to_many association in Rails is a way to define a many-to-many relationship between two models.
  54. What is the purpose of the validates_presence_of method in Rails?
    Answer: The validates_presence_of method in Rails is a way to ensure that a model attribute is not blank or nil.
  55. What is the purpose of the validates_uniqueness_of method in Rails?
    Answer: The validates_uniqueness_of method in Rails is a way to ensure that a model attribute is unique among all the records in the database.
  56. What is the purpose of the has_one_through association in Rails?
    Answer: The has_one_through association in Rails is a way to define a one-to-one relationship between two models that are not directly related.
  57. What is the purpose of the before_save callback in Rails?
    Answer: The before_save callback in Rails is a way to specify a method that should be called before a record is saved to the database, which can be used to perform common tasks such as updating timestamps or calculating derived values.
  58. What is the purpose of the after_save callback in Rails?
    Answer: The after_save callback in Rails is a way to specify a method that should be called after a record is saved to the database, which can be used to perform common tasks such as updating associated records or sending notifications.
  59. What is the purpose of the before_create callback in Rails?
    Answer: The before_create callback in Rails is a way to specify a method that should be called before a new record is created in the database, which can be used to perform common tasks such as setting default values or generating unique identifiers.
  60. What is the purpose of the after_create callback in Rails?
    Answer: The after_create callback in Rails is a way to specify a method that should be called after a new record is created in the database, which can be used to perform common tasks such as sending notifications or updating associated records.
  61. What is the purpose of the before_destroy callback in Rails?
    Answer: The before_destroy callback in Rails is a way to specify a method that should be called before a record is destroyed in the database, which can be used to perform common tasks such as checking for dependent records or updating associated records.
  62. What is the purpose of the after_destroy callback in Rails?
    Answer: The after_destroy callback in Rails is a way to specify a method that should be called after a record is destroyed in the database, which can be used to perform common tasks such as cleaning up associated records or sending notifications.
  63. What is the purpose of the belongs_to_polymorphic association in Rails?
    Answer: The belongs_to_polymorphic association in Rails is a way to define a polymorphic relationship between two models, where the associated model can be of any type.
  64. What is the purpose of the has_many_polymorphic association in Rails?
    Answer: The has_many_polymorphic association in Rails is a way to define a polymorphic relationship between two models, where the associated model can be of any type and can be associated with multiple records.
  65. What is the purpose of the delegate method in Rails?
    Answer: The delegate method in Rails is a way to define a method in a model that delegates its implementation to another object, such as an associated record.
  66. What is the purpose of the scope method in Rails?
    Answer: The scope method in Rails is a way to define a named scope for a model, which can be used to filter records based on a specific set of conditions.
  67. What is the purpose of the pluck method in Rails?
    Answer: The pluck method in Rails is a way to retrieve a specific column or set of columns from a database table as an array.
  68. What is the purpose of the enum method in Rails?
    Answer: The enum method in Rails is a way to define a set of named values for a model attribute, which can be used to simplify validation and querying.
  69. What is the purpose of the has_many_through association in Rails?
    Answer: The has_many_through association in Rails is a way to define a many-to-many relationship between two models through an intermediate model.
  70. What is the purpose of the through option in Rails associations?
    Answer: The through option in Rails associations is a way to specify the intermediate model for a many-to-many relationship, when using the has_many_through or has_one_through associations.
  71. What is the purpose of the dependent option in Rails associations?
    Answer: The dependent option in Rails associations is a way to specify what should happen to associated records when a record is destroyed, such as destroying them, nullifying their foreign keys, or restricting their deletion.
  72. What is the purpose of the validates_format_of method in Rails?
    Answer: The validates_format_of method in Rails is a way to ensure that a model attribute matches a specific regular expression.
  73. What is the purpose of the validates_length_of method in Rails?
    Answer: The validates_length_of method in Rails is a way to ensure that a model attribute has a specific length or falls within a specific range of lengths.
  74. What is the purpose of the validates_numericality_of method in Rails?
    Answer: The validates_numericality_of method in Rails is a way to ensure that a model attribute is a valid numeric value.
  75. What is the purpose of the validates_associated method in Rails?
    Answer: The validates_associated method in Rails is a way to ensure that all associated records for a given model are valid.
  76. What is the purpose of the validates_presence_of method in Rails?
    Answer: The validates_presence_of method in Rails is a way to ensure that a model attribute is present and not blank.
  77. What is the purpose of the validates_uniqueness_of method in Rails?
    Answer: The validates_uniqueness_of method in Rails is a way to ensure that a model attribute is unique across all records in a database table.
  78. What is the purpose of the validates_inclusion_of method in Rails?
    Answer: The validates_inclusion_of method in Rails is a way to ensure that a model attribute is included in a specific set of values.
  79. What is the purpose of the validates_exclusion_of method in Rails?
    Answer: The validates_exclusion_of method in Rails is a way to ensure that a model attribute is excluded from a specific set of values.
  80. What is the purpose of the validates_acceptance_of method in Rails?
    Answer: The validates_acceptance_of method in Rails is a way to ensure that a boolean model attribute is set to true.
  81. What is the purpose of the validates_confirmation_of method in Rails?
    Answer: The validates_confirmation_of method in Rails is a way to ensure that a model attribute is confirmed by the user, typically through a second input field.
  82. What is the purpose of the after_save callback in Rails?
    Answer: The after_save callback in Rails is a way to specify a method that should be called after a record is saved to the database, which can be used to perform common tasks such as sending notifications or updating associated records.
  83. What is the purpose of the before_update callback in Rails?
    Answer: The before_update callback in Rails is a way to specify a method that should be called before a record is updated in the database, which can be used to perform common tasks such as generating a slug or updating a timestamp.
  84. What is the purpose of the after_update callback in Rails?
    Answer: The after_update callback in Rails is a way to specify a method that should be called after a record is updated in the database, which can be used to perform common tasks such as sending notifications or updating associated records.
  85. What is the purpose of the before_commit callback in Rails?
    Answer: The before_commit callback in Rails is a way to specify a method that should be called before a transaction is committed to the database, which can be used to perform common tasks such as updating associated records.
  86. What is the purpose of the before_rollback callback in Rails?
    Answer: The before_rollback callback in Rails is a way to specify a method that should be called before a transaction is rolled back, which can be used to perform common tasks such as cleaning up temporary files or sending notifications.
  87. What is the purpose of the around_save callback in Rails?
    Answer: The around_save callback in Rails is a way to specify a method that should be called before and after a record is saved to the database, which can be used to perform common tasks such as logging or updating dependent records.
  88. What is the purpose of the around_create callback in Rails?
    Answer: The around_create callback in Rails is a way to specify a method that should be called before and after a record is created in the database, which can be used to perform common tasks such as generating a slug or updating a timestamp.
  89. What is the purpose of the around_update callback in Rails?
    Answer: The around_update callback in Rails is a way to specify a method that should be called before and after a record is updated in the database, which can be used to perform common tasks such as logging or sending notifications.
  90. What is the purpose of the around_destroy callback in Rails?
    Answer: The around_destroy callback in Rails is a way to specify a method that should be called before and after a record is destroyed from the database, which can be used to perform common tasks such as logging or updating associated records.
  91. What is the purpose of the before_filter method in Rails?
    Answer: The before_filter method in Rails is a way to specify a method that should be called before a controller action is executed, which can be used to perform common tasks such as authentication or authorization.
  92. What is the purpose of the skip_before_filter method in Rails?
    Answer: The skip_before_filter method in Rails is a way to skip the execution of a specified before_filter method for a controller action.
  93. What is the purpose of the after_filter method in Rails?
    Answer: The after_filter method in Rails is a way to specify a method that should be called after a controller action is executed, which can be used to perform common tasks such as logging or sending notifications.
  94. What is the purpose of the skip_after_filter method in Rails?
    Answer: The skip_after_filter method in Rails is a way to skip the execution of a specified after_filter method for a controller action.
  95. What is the purpose of the around_filter method in Rails?
    Answer: The around_filter method in Rails is a way to specify a method that should be called before and after a controller action is executed, which can be used to perform common tasks such as logging or authentication.
  96. What is the purpose of the skip_around_filter method in Rails?
    Answer: The skip_around_filter method in Rails is a way to skip the execution of a specified around_filter method for a controller action.
  97. What is the purpose of the render method in Rails?
    Answer: The render method in Rails is a way to generate a response to a request, typically by rendering a view template or returning JSON or XML data.
  98. What is the purpose of the redirect_to method in Rails?
    Answer: The redirect_to method in Rails is a way to redirect a user to a new URL, typically in response to a successful form submission or authentication.
  99. What is the purpose of the link_to method in Rails?
    Answer: The link_to method in Rails is a way to generate an HTML link that can be used to navigate to a specific URL or perform a specific action.
  100. What is the purpose of the form
Answer: The purpose of the form_for method in Rails is to generate an HTML form that can be used to submit data to the server, typically for creating or         updating records in the database.


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yes blog.rubyonrails.ba
Nezir Zahirovic
Ruby On Rails Full stack last 8 years.
C#, ASP.NET, JavaScript, SQL, CSS, Bootstrap 11 years.

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