module Sequel::Model::DatasetMethods

DatasetMethods contains methods that all model datasets have.

Public Instance Methods

[](*args) click to toggle source

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
Calls superclass method
# File lib/sequel/model/base.rb, line 2088
def [](*args)
  if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
    with_pk(i)
  else
    super
  end
end
as_hash(key_column=nil, value_column=nil, opts=OPTS) click to toggle source

This allows you to call as_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.as_hash # SELECT * FROM artists
# => {1=>#<Artist {:id=>1, ...}>,
#     2=>#<Artist {:id=>2, ...}>,
#     ...}
Calls superclass method
# File lib/sequel/model/base.rb, line 2147
def as_hash(key_column=nil, value_column=nil, opts=OPTS)
  if key_column
    super
  else
    raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
    super(pk, value_column, opts) 
  end
end
destroy() click to toggle source

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)
# ...
# File lib/sequel/model/base.rb, line 2105
def destroy
  pr = proc{all(&:destroy).length}
  model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
end
last(*a, &block) click to toggle source

If there is no order already defined on this dataset, order it by the primary key and call last.

Album.last
# SELECT * FROM albums ORDER BY id DESC LIMIT 1
Calls superclass method
# File lib/sequel/model/base.rb, line 2115
def last(*a, &block)
  if ds = _primary_key_order
    ds.last(*a, &block)
  else
    super
  end
end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
# File lib/sequel/model/base.rb, line 2080
def model
  @opts[:model]
end
paged_each(*a, &block) click to toggle source

If there is no order already defined on this dataset, order it by the primary key and call paged_each.

Album.paged_each{|row| }
# SELECT * FROM albums ORDER BY id LIMIT 1000 OFFSET 0
# SELECT * FROM albums ORDER BY id LIMIT 1000 OFFSET 1000
# SELECT * FROM albums ORDER BY id LIMIT 1000 OFFSET 2000
# ...
Calls superclass method
# File lib/sequel/model/base.rb, line 2131
def paged_each(*a, &block)
  if ds = _primary_key_order
    ds.paged_each(*a, &block)
  else
    super
  end
end
to_hash(*a) click to toggle source

Alias of #as_hash for backwards compatibility.

# File lib/sequel/model/base.rb, line 2157
def to_hash(*a)
  as_hash(*a)
end
with_pk(pk) click to toggle source

Given a primary key value, return the first record in the dataset with that primary key value. If no records matches, returns nil.

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

# Composite primary key
Artist.dataset.with_pk([1, 2])
# SELECT * FROM artists WHERE ((artists.id1 = 1) AND (artists.id2 = 2)) LIMIT 1
# File lib/sequel/model/base.rb, line 2171
def with_pk(pk)
  if pk && (loader = _with_pk_loader)
    loader.first(*pk)
  else
    first(model.qualified_primary_key_hash(pk))
  end
end
with_pk!(pk) click to toggle source

Same as #with_pk, but raises NoMatchingRow instead of returning nil if no row matches.

# File lib/sequel/model/base.rb, line 2181
def with_pk!(pk)
  with_pk(pk) || raise(NoMatchingRow.new(self))
end

Private Instance Methods

_primary_key_order() click to toggle source

If the dataset is not already ordered, and the model has a primary key, return a clone ordered by the primary key.

# File lib/sequel/model/base.rb, line 2189
def _primary_key_order
  if @opts[:order].nil? && model && (pk = model.primary_key)
    cached_dataset(:_pk_order_ds){order(*pk)}
  end
end
_with_pk_loader() click to toggle source

A cached placeholder literalizer, if one exists for the current dataset.

# File lib/sequel/model/base.rb, line 2196
def _with_pk_loader
  cached_placeholder_literalizer(:_with_pk_loader) do |pl|
    table = model.table_name
    cond = case primary_key = model.primary_key
    when Array
      primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
    when Symbol
      {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
    else
      raise(Error, "#{model} does not have a primary key")
    end

    where(cond).limit(1)
  end
end
non_sql_option?(key) click to toggle source
Calls superclass method
# File lib/sequel/model/base.rb, line 2212
def non_sql_option?(key)
  super || key == :model
end