Retrieve a specific element using an ID from this set.

Example:

  # Let's say we got the ID 1 from a request parameter.
  id = 1

  # Retrieve the post if it's included in the user's posts.
  post = user.posts[id]

Perform an intersection between the existent set and the new set created by the union of the passed filters.

Example:

  set = User.find(:status => "active")
  set.combine(:name => ["John", "Jane"])

  # The result will include all users with active status
  # and with names "John" or "Jane".

Reduce the set using any number of filters.

Example:

  set = User.find(:name => "John")
  set.except(:country => "US")

  # You can also do it in one line.
  User.find(:name => "John").except(:country => "US")

Returns true if id is included in the set. Otherwise, returns false.

Example:

  class Post < Ohm::Model
  end

  class User < Ohm::Model
    set :posts, :Post
  end

  user = User.create
  post = Post.create
  user.posts.add(post)

  user.posts.exists?('nonexistent') # => false
  user.posts.exists?(post.id)       # => true

Chain new fiters on an existing set.

Example:

  set = User.find(:name => "John")
  set.find(:age => 30)

Returns the first record of the set. Internally uses `sort` or `sort_by` if a `:by` option is given. Accepts all options supported by `sort`.

  class User < Ohm::Model
    attribute :name
  end

  User.create(name: "alice")
  User.create(name: "bob")
  User.create(name: "eve")

  User.all.first.name # => "alice"
  User.all.first(by: :name).name # => "alice"

  User.all.first(order: "ASC")  # => "alice"
  User.all.first(order: "DESC") # => "eve"

You can use the `:order` option to bring the last record:

  User.all.first(order: "DESC").name             # => "eve"
  User.all.first(by: :name, order: "ALPHA DESC") # => "eve"

Returns an array with all the ID‘s of the set.

  class Post < Ohm::Model
  end

  class User < Ohm::Model
    attribute :name
    index :name

    set :posts, :Post
  end

  User.create(name: "John")
  User.create(name: "Jane")

  User.all.ids
  # => ["1", "2"]

  User.find(name: "John").union(name: "Jane").ids
  # => ["1", "2"]

Check if a model is included in this set.

Example:

  u = User.create

  User.all.include?(u)
  # => true

Note: Ohm simply checks that the model‘s ID is included in the set. It doesn‘t do any form of type checking.

Returns the total size of the set using SCARD.

Allows you to sort your models using their IDs. This is much faster than `sort_by`. If you simply want to get records in ascending or descending order, then this is the best method to do that.

Example:

  class User < Ohm::Model
    attribute :name
  end

  User.create(:name => "John")
  User.create(:name => "Jane")

  User.all.sort.map(&:id) == ["1", "2"]
  # => true

  User.all.sort(:order => "ASC").map(&:id) == ["1", "2"]
  # => true

  User.all.sort(:order => "DESC").map(&:id) == ["2", "1"]
  # => true

Allows you to sort by any attribute in the hash, this doesn‘t include the id. If you want to sort by ID, use sort.

  class User < Ohm::Model
    attribute :name
  end

  User.all.sort_by(:name, :order => "ALPHA")
  User.all.sort_by(:name, :order => "ALPHA DESC")
  User.all.sort_by(:name, :order => "ALPHA DESC", :limit => [0, 10])

Note: This is slower compared to just doing `sort`, specifically because Redis has to read each individual hash in order to sort them.

Do a union to the existing set using any number of filters.

Example:

  set = User.find(:name => "John")
  set.union(:name => "Jane")

  # You can also do it in one line.
  User.find(:name => "John").union(:name => "Jane")