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 2505
def [](*args)
  if args.length == 1 && (i = args.at(0)) && i.is_a?(Integer)
    with_pk(i)
  else
    super
  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 2522
def destroy
  pr = proc{all(&:destroy).length}
  model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
end
graph(table, *args, &block) click to toggle source

Allow Sequel::Model classes to be used as dataset arguments when graphing:

Artist.graph(Album, :artist_id=>id)
# SELECT artists.id, artists.name, albums.id AS albums_id, albums.artist_id, albums.name AS albums_name
# FROM artists LEFT OUTER JOIN albums ON (albums.artist_id = artists.id)
Calls superclass method
# File lib/sequel/model/base.rb, line 2532
def graph(table, *args, &block)
  if table.is_a?(Class) && table < Sequel::Model
    super(table.dataset, *args, &block)
  else
    super
  end
end
insert_sql(*values) click to toggle source

Handle Sequel::Model instances when inserting, using the model instance's values for the insert, unless the model instance can be used directly in SQL.

Album.insert(Album.load(:name=>'A'))
# INSERT INTO albums (name) VALUES ('A')
Calls superclass method
# File lib/sequel/model/base.rb, line 2546
def insert_sql(*values)
  if values.size == 1 && (v = values.at(0)).is_a?(Sequel::Model) && !v.respond_to?(:sql_literal_append)
    super(v.to_hash)
  else
    super
  end
end
join_table(type, table, *args, &block) click to toggle source

Allow Sequel::Model classes to be used as table name arguments in dataset join methods:

Artist.join(Album, :artist_id=>id)
# SELECT * FROM artists INNER JOIN albums ON (albums.artist_id = artists.id)
Calls superclass method
# File lib/sequel/model/base.rb, line 2559
def join_table(type, table, *args, &block)
  if table.is_a?(Class) && table < Sequel::Model
    if table.dataset.simple_select_all?
      super(type, table.table_name, *args, &block)
    else
      super(type, table.dataset, *args, &block)
    end
  else
    super
  end
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 2576
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 2497
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 2592
def paged_each(*a, &block)
  if ds = _primary_key_order
    ds.paged_each(*a, &block)
  else
    super
  end
end
to_hash(key_column=nil, value_column=nil, opts=OPTS) click to toggle source

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, ...}>,
#     ...}
Calls superclass method
# File lib/sequel/model/base.rb, line 2608
def to_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
where_all(cond, &block) click to toggle source

Return an array of all rows matching the given filter condition, also yielding each row to the given block. Basically the same as where(cond).all(&block), except it can be optimized to not create an intermediate dataset.

Artist.where_all(:id=>[1,2,3])
# SELECT * FROM artists WHERE (id IN (1, 2, 3))
# File lib/sequel/model/base.rb, line 2623
def where_all(cond, &block)
  if loader = _model_where_loader
    loader.all(filter_expr(cond), &block)
  else
    where(cond).all(&block)
  end
end
where_each(cond, &block) click to toggle source

Iterate over all rows matching the given filter condition, yielding each row to the given block. Basically the same as where(cond).each(&block), except it can be optimized to not create an intermediate dataset.

Artist.where_each(:id=>[1,2,3]){|row| p row}
# SELECT * FROM artists WHERE (id IN (1, 2, 3))
# File lib/sequel/model/base.rb, line 2637
def where_each(cond, &block)
  if loader = _model_where_loader
    loader.each(filter_expr(cond), &block)
  else
    where(cond).each(&block)
  end
end
where_single_value(cond) click to toggle source

Filter the datasets using the given filter condition, then return a single value. This assumes that the dataset has already been setup to limit the selection to a single column. Basically the same as where(cond).single_value, except it can be optimized to not create an intermediate dataset.

Artist.select(:name).where_single_value(:id=>1)
# SELECT name FROM artists WHERE (id = 1) LIMIT 1
# File lib/sequel/model/base.rb, line 2652
def where_single_value(cond)
  if loader = cached_placeholder_literalizer(:_model_where_single_value_loader) do |pl|
      single_value_ds.where(pl.arg)
    end

    loader.get(filter_expr(cond))
  else
    where(cond).single_value
  end
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 2673
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 2683
def with_pk!(pk)
  with_pk(pk) || raise(NoMatchingRow.new(self))
end

Private Instance Methods

_model_where_loader() click to toggle source

Loader used for #where_all and where_each.

# File lib/sequel/model/base.rb, line 2690
def _model_where_loader
  cached_placeholder_literalizer(:_model_where_loader) do |pl|
    where(pl.arg)
  end
end
_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 2698
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 2705
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