Class: Sequel::Model::Associations::EagerGraphLoader

Inherits:
Object
  • Object
show all
Defined in:
lib/sequel/model/associations.rb

Overview

This class is the internal implementation of eager_graph. It is responsible for taking an array of plain hashes and returning an array of model objects with all eager_graphed associations already set in the association cache.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(dataset) ⇒ EagerGraphLoader

Initialize all of the data structures used during loading.



3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
 
# File 'lib/sequel/model/associations.rb', line 3488

def initialize(dataset)
  opts = dataset.opts
  eager_graph = opts[:eager_graph]
  @master =  eager_graph[:master]
  requirements = eager_graph[:requirements]
  reflection_map = @reflection_map = eager_graph[:reflections]
  reciprocal_map = @reciprocal_map = eager_graph[:reciprocals]
  limit_map = @limit_map = eager_graph[:limits]
  @unique = eager_graph[:cartesian_product_number] > 1
      
  alias_map = @alias_map = {}
  type_map = @type_map = {}
  after_load_map = @after_load_map = {}
  reflection_map.each do |k, v|
    alias_map[k] = v[:name]
    after_load_map[k] = v[:after_load] if v[:after_load]
    type_map[k] = if v.returns_array?
      true
    elsif (limit_and_offset = limit_map[k]) && !limit_and_offset.last.nil?
      :offset
    end
  end
  after_load_map.freeze
  alias_map.freeze
  type_map.freeze

  # Make dependency map hash out of requirements array for each association.
  # This builds a tree of dependencies that will be used for recursion
  # to ensure that all parts of the object graph are loaded into the
  # appropriate subordinate association.
  dependency_map = @dependency_map = {}
  # Sort the associations by requirements length, so that
  # requirements are added to the dependency hash before their
  # dependencies.
  requirements.sort_by{|a| a[1].length}.each do |ta, deps|
    if deps.empty?
      dependency_map[ta] = {}
    else
      deps = deps.dup
      hash = dependency_map[deps.shift]
      deps.each do |dep|
        hash = hash[dep]
      end
      hash[ta] = {}
    end
  end
  freezer = lambda do |h|
    h.freeze
    h.each_value(&freezer)
  end
  freezer.call(dependency_map)
      
  datasets = opts[:graph][:table_aliases].to_a.reject{|ta,ds| ds.nil?}
  column_aliases = opts[:graph][:column_aliases]
  primary_keys = {}
  column_maps = {}
  models = {}
  row_procs = {}
  datasets.each do |ta, ds|
    models[ta] = ds.model
    primary_keys[ta] = []
    column_maps[ta] = {}
    row_procs[ta] = ds.row_proc
  end
  column_aliases.each do |col_alias, tc|
    ta, column = tc
    column_maps[ta][col_alias] = column
  end
  column_maps.each do |ta, h|
    pk = models[ta].primary_key
    if pk.is_a?(Array)
      primary_keys[ta] = []
      h.select{|ca, c| primary_keys[ta] << ca if pk.include?(c)}
    else
      h.select{|ca, c| primary_keys[ta] = ca if pk == c}
    end
  end
  @column_maps = column_maps.freeze
  @primary_keys = primary_keys.freeze
  @row_procs = row_procs.freeze

  # For performance, create two special maps for the master table,
  # so you can skip a hash lookup.
  @master_column_map = column_maps[master]
  @master_primary_keys = primary_keys[master]

  # Add a special hash mapping table alias symbols to 5 element arrays that just
  # contain the data in other data structures for that table alias.  This is
  # used for performance, to get all values in one hash lookup instead of
  # separate hash lookups for each data structure.
  ta_map = {}
  alias_map.each_key do |ta|
    ta_map[ta] = [row_procs[ta], alias_map[ta], type_map[ta], reciprocal_map[ta]].freeze
  end
  @ta_map = ta_map.freeze
  freeze
end

Instance Attribute Details

#after_load_map ⇒ Object (readonly)

Hash with table alias symbol keys and after_load hook values



3446
3447
3448
 
# File 'lib/sequel/model/associations.rb', line 3446

def after_load_map
  @after_load_map
end

#alias_map ⇒ Object (readonly)

Hash with table alias symbol keys and association name values



3449
3450
3451
 
# File 'lib/sequel/model/associations.rb', line 3449

def alias_map
  @alias_map
end

#column_maps ⇒ Object (readonly)

Hash with table alias symbol keys and subhash values mapping column_alias symbols to the symbol of the real name of the column



3453
3454
3455
 
# File 'lib/sequel/model/associations.rb', line 3453

def column_maps
  @column_maps
end

#dependency_map ⇒ Object (readonly)

Recursive hash with table alias symbol keys mapping to hashes with dependent table alias symbol keys.



3456
3457
3458
 
# File 'lib/sequel/model/associations.rb', line 3456

def dependency_map
  @dependency_map
end

#limit_map ⇒ Object (readonly)

Hash with table alias symbol keys and [limit, offset] values



3459
3460
3461
 
# File 'lib/sequel/model/associations.rb', line 3459

def limit_map
  @limit_map
end

#master ⇒ Object (readonly)

The table alias symbol for the primary model



3462
3463
3464
 
# File 'lib/sequel/model/associations.rb', line 3462

def master
  @master
end

#primary_keys ⇒ Object (readonly)

Hash with table alias symbol keys and primary key symbol values (or arrays of primary key symbols for composite key tables)



3466
3467
3468
 
# File 'lib/sequel/model/associations.rb', line 3466

def primary_keys
  @primary_keys
end

#reciprocal_map ⇒ Object (readonly)

Hash with table alias symbol keys and reciprocal association symbol values, used for setting reciprocals for one_to_many associations.



3470
3471
3472
 
# File 'lib/sequel/model/associations.rb', line 3470

def reciprocal_map
  @reciprocal_map
end

#records_map ⇒ Object (readonly)

Hash with table alias symbol keys and subhash values mapping primary key symbols (or array of symbols) to model instances. Used so that only a single model instance is created for each object.



3474
3475
3476
 
# File 'lib/sequel/model/associations.rb', line 3474

def records_map
  @records_map
end

#reflection_map ⇒ Object (readonly)

Hash with table alias symbol keys and AssociationReflection values



3477
3478
3479
 
# File 'lib/sequel/model/associations.rb', line 3477

def reflection_map
  @reflection_map
end

#row_procs ⇒ Object (readonly)

Hash with table alias symbol keys and callable values used to create model instances



3480
3481
3482
 
# File 'lib/sequel/model/associations.rb', line 3480

def row_procs
  @row_procs
end

#type_map ⇒ Object (readonly)

Hash with table alias symbol keys and true/false values, where true means the association represented by the table alias uses an array of values instead of a single value (i.e. true => *_many, false => *_to_one).



3485
3486
3487
 
# File 'lib/sequel/model/associations.rb', line 3485

def type_map
  @type_map
end

Instance Method Details

#load(hashes) ⇒ Object

Return an array of primary model instances with the associations cache prepopulated for all model objects (both primary and associated).



3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
 
# File 'lib/sequel/model/associations.rb', line 3588

def load(hashes)
  # This mapping is used to make sure that duplicate entries in the
  # result set are mapped to a single record.  For example, using a
  # single one_to_many association with 10 associated records,
  # the main object column values appear in the object graph 10 times.
  # We map by primary key, if available, or by the object's entire values,
  # if not. The mapping must be per table, so create sub maps for each table
  # alias.
  @records_map = records_map = {}
  alias_map.keys.each{|ta| records_map[ta] = {}}

  master = master()
      
  # Assign to local variables for speed increase
  rp = row_procs[master]
  rm = records_map[master] = {}
  dm = dependency_map

  records_map.freeze

  # This will hold the final record set that we will be replacing the object graph with.
  records = []

  hashes.each do |h|
    unless key = master_pk(h)
      key = hkey(master_hfor(h))
    end
    unless primary_record = rm[key]
      primary_record = rm[key] = rp.call(master_hfor(h))
      # Only add it to the list of records to return if it is a new record
      records.push(primary_record)
    end
    # Build all associations for the current object and it's dependencies
    _load(dm, primary_record, h)
  end
      
  # Remove duplicate records from all associations if this graph could possibly be a cartesian product
  # Run after_load procs if there are any
  post_process(records, dm) if @unique || !after_load_map.empty? || !limit_map.empty?

  records_map.each_value(&:freeze)
  freeze

  records
end