Assume if a single integer is given that it is a lookup by primary key, and call with_pk with the argument.

  Artist.dataset[1] # SELECT * FROM artists WHERE (id = 1) LIMIT 1

[Source]

      # File lib/sequel/model/base.rb, line 1727
1727:       def [](*args)
1728:         if args.length == 1 && (i = args.at(0)) && i.is_a?(Integer)
1729:           with_pk(i)
1730:         else
1731:           super
1732:         end
1733:       end

Destroy each row in the dataset by instantiating it and then calling destroy on the resulting model object. This isn‘t as fast as deleting the dataset, which does a single SQL call, but this runs any destroy hooks on each object in the dataset.

  Artist.dataset.destroy
  # DELETE FROM artists WHERE (id = 1)
  # DELETE FROM artists WHERE (id = 2)
  # ...

[Source]

      # File lib/sequel/model/base.rb, line 1744
1744:       def destroy
1745:         pr = proc{all{|r| r.destroy}.length}
1746:         model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
1747:       end

This allows you to call to_hash without any arguments, which will result in a hash with the primary key value being the key and the model object being the value.

  Artist.dataset.to_hash # SELECT * FROM artists
  # => {1=>#<Artist {:id=>1, ...}>,
  #     2=>#<Artist {:id=>2, ...}>,
  #     ...}

[Source]

      # File lib/sequel/model/base.rb, line 1757
1757:       def to_hash(key_column=nil, value_column=nil)
1758:         if key_column
1759:           super
1760:         else
1761:           raise(Sequel::Error, "No primary key for model") unless model and pk = model.primary_key
1762:           super(pk, value_column) 
1763:         end
1764:       end

Given a primary key value, return the first record in the dataset with that primary key value.

  # Single primary key
  Artist.dataset.with_pk(1) # SELECT * FROM artists WHERE (id = 1) LIMIT 1

  # Composite primary key
  Artist.dataset.with_pk([1, 2]) # SELECT * FROM artists
                                 # WHERE ((id1 = 1) AND (id2 = 2)) LIMIT 1

[Source]

      # File lib/sequel/model/base.rb, line 1775
1775:       def with_pk(pk)
1776:         first(model.qualified_primary_key_hash(pk))
1777:       end