Rails create or update magic

Question

I have a class called CachedObject that stores generic serialised objects indexed by key  I want this class to implement a create or update method  If an object is found it will update it  otherwise it will create a new one   Is there a way to do this in Rails or do I have to write my own method

User · Answer

You can do it in one statement like this   CachedObject where key   the given key   first or create  do  cached     cached attribute1    attribute value     cached attribute2    attribute value  end

User · Answer

Add this to your model   def self update or create by args  attributes    obj   self find or create by args    obj update attributes    return obj end   With that  you can   User update or create by  name   Joe    attributes

User · Answer

Old question but throwing my solution into the ring for completeness  I needed this when I needed a specific find but a different create if it doesn t exist   def self find by or create with args  attributes    READ CAREFULLY  args for finding  attributes for creating          obj   self find or initialize by args          return obj if obj persisted          return obj if obj update attributes attributes   end

User · Answer

The magic you have been looking for has been added in Rails 6 Now you can upsert  update or insert   For single record use   Model upsert column name  value    For multiple records use upsert all    Model upsert all column name  value  unique by   column name    Note     Both methods do not trigger Active Record callbacks or validations unique by    PostgreSQL and SQLite only

User · Answer

The sequel gem adds an update or create method which seems to do what you re looking for

User · Answer

Rails 6  Rails 6 added an upsert and upsert all methods that deliver this functionality   Model upsert column name  value        upsert  It does not instantiate any models nor does it trigger Active Record callbacks or validations     Rails 5  4  and 3  Not if you are looking for an  upsert   where the database executes an update or an insert statement in the same operation  type of statement  Out of the box  Rails and ActiveRecord have no such feature  You can use the upsert gem  however   Otherwise  you can use  find or initialize by or find or create by  which offer similar functionality  albeit at the cost of an additional database hit  which  in most cases  is hardly an issue at all  So unless you have serious performance concerns  I would not use the gem   For example  if no user is found with the name  Roger   a new user instance is instantiated with its name set to  Roger    user   User where name   Roger   first or initialize user email    email example com  user save   Alternatively  you can use find or initialize by   user   User find or initialize by name   Roger     In Rails 3   user   User find or initialize by name  Roger   user email    email example com  user save   You can use a block  but the block only runs if the record is new   User where name   Roger   first or initialize do  user      this won t run if a user with name  Roger  is found   user save  end  User find or initialize by name   Roger   do  user      this also won t run if a user with name  Roger  is found   user save end   If you want to use a block regardless of the record s persistence  use tap on the result   User where name   Roger   first or initialize tap do  user    user email    email example com    user save end

User · Answer

In Rails 4 you can add to a specific model   def self update or create attributes    assign or new attributes  save end  def self assign or new attributes    obj   first    new   obj assign attributes attributes    obj end   and use it like  User where email   a b com   update or create name   Mr A Bbb       Or if you d prefer to add these methods to all models put in an initializer   module ActiveRecordExtras   module Relation     extend ActiveSupport  Concern      module ClassMethods       def update or create attributes          assign or new attributes  save       end        def update or create  attributes          assign or new attributes  save        end        def assign or new attributes          obj   first    new         obj assign attributes attributes          obj       end     end   end end  ActiveRecord  Base send  include  ActiveRecordExtras  Relation

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