What is the difference between delete and destroy rails?
The delete method essentially deletes a row (or an array of rows) from the database. Destroy on the other hand allows for a few more options. First, it will check any callbacks such as before_delete, or any dependencies that we specify in our model.
What is the difference between dependent => destroy and dependent => Delete_all in rails?
:Dependent possible options: :destroy causes all the associated objects to also be destroyed. :delete_all causes all the associated objects to be deleted directly from the database (so callbacks will not be executed).
How to destroy a record in rails?
Rails Delete operation using delete method Unlike the destroy method, with delete, you can remove a record directly from the database. Any dependencies to other records in the model are not taken into account. The method delete only deletes that one row in the database and nothing else.
How we can destroy a model in Ruby?
- To remove migration (if you already migrated the migration) rake db:migrate:down VERSION=”20130417185845″ #Your migration version.
- To remove Model rails d model name #name => Your model name.
What is delegate in Ruby on rails?
delegate provides a delegate class method to easily expose contained objects’ public methods as your own. Simply say, through delegation you can use public methods in other model directly. And the name of the target object via the :to option(also a symbol or string).
What is dependent destroy rails?
dependent: :destroy Rails, when attempting to destroy an instance of the Parent, will also iteratively go through each child of the parent calling destroy on the child. (The children are deleted first, then the parent, avoiding the DB complaining about a foreign key being invalid.)
What is the difference between Has_one and Belongs_to?
They essentially do the same thing, the only difference is what side of the relationship you are on. If a User has a Profile , then in the User class you’d have has_one :profile and in the Profile class you’d have belongs_to :user .
What is Rails Active Record?
Rails Active Records provide an interface and binding between the tables in a relational database and the Ruby program code that manipulates database records. Each Active Record object has CRUD (Create, Read, Update, and Delete) methods for database access.
How do you delete all records in Rails?
- 3) Drop the whole database and bring it back up again. We can achieve this with rake:db:drop , then rake:db:setup .
- 2) destroy_all. Destroys the records by instantiating each record and calling its #destroy method.
- 1) delete_all 👑
What is the difference between collect and map in Ruby?
There’s no difference, in fact map is implemented in C as rb_ary_collect and enum_collect (eg. there is a difference between map on an array and on any other enum, but no difference between map and collect ). Why do both map and collect exist in Ruby? The map function has many naming conventions in different languages.
What happens when you call delete in ActiveRecord?
This is what ActiveRecord does when calling the delete method: In basic terms, using delete removes the row i n the database using a primary key matching the id argument, using a SQL DELETE statement, and returns the number of rows deleted. You can delete multiple rows at once by passing an Array of ids. But when calling delete, that’s it.
What’s the difference between destroy and delete in has _ many?
For has_many, destroy and destroy_all will always call the destroy method of the record (s) being removed so that callbacks are run. However delete and delete_all will either do the deletion according to the strategy specified by the :dependent option, or if no :dependent option is given, then it will follow the default strategy.
Which is faster to delete or destroy in Ruby?
In general, delete is faster than destroy. User.destroy (1) will delete user with id == 1 and :before_destroy and :after_destroy callbacks occur. For example if you have associated records After user is destroyed his addresses will be destroyed too.
What’s the difference between delete, destroy and destroy in rails?
There is delete, delete_all, destroy, and destroy_all. The docs are: older docsand Rails 3.0.0 docs deletedoesn’t instantiate the objects, while destroydoes. In general, deleteis faster than destroy.