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.



3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
 
# File 'lib/sequel/model/associations.rb', line 3205

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] unless v[:after_load].empty?
    type_map[k] = if v.returns_array?
      true
    elsif (limit_and_offset = limit_map[k]) && !limit_and_offset.last.nil?
      :offset
    end
  end

  # 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 = {}
  # 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
      
  # 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 = {@master=>{}}
  alias_map.keys.each{|ta| records_map[ta] = {}}
  @records_map = records_map

  datasets = opts[:graph][:table_aliases].to_a.reject{|ta,ds| ds.nil?}
  column_aliases = opts[:graph_aliases] || opts[:graph][:column_aliases] # SEQUEL5: Remove :graph_aliases support
  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
  @primary_keys = primary_keys
  @row_procs = row_procs

  # 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.keys.each do |ta|
    ta_map[ta] = [records_map[ta], row_procs[ta], alias_map[ta], type_map[ta], reciprocal_map[ta]]
  end
  @ta_map = ta_map
end

Instance Attribute Details

#after_load_map ⇒ Object (readonly)

Hash with table alias symbol keys and after_load hook values



3162
3163
3164
 
# File 'lib/sequel/model/associations.rb', line 3162

def after_load_map
  @after_load_map
end

#alias_map ⇒ Object (readonly)

Hash with table alias symbol keys and association name values



3165
3166
3167
 
# File 'lib/sequel/model/associations.rb', line 3165

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



3169
3170
3171
 
# File 'lib/sequel/model/associations.rb', line 3169

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.



3172
3173
3174
 
# File 'lib/sequel/model/associations.rb', line 3172

def dependency_map
  @dependency_map
end

#limit_map ⇒ Object (readonly)

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



3175
3176
3177
 
# File 'lib/sequel/model/associations.rb', line 3175

def limit_map
  @limit_map
end

#master ⇒ Object (readonly)

Hash with table alias symbol keys and callable values used to create model instances The table alias symbol for the primary model



3179
3180
3181
 
# File 'lib/sequel/model/associations.rb', line 3179

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)



3183
3184
3185
 
# File 'lib/sequel/model/associations.rb', line 3183

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.



3187
3188
3189
 
# File 'lib/sequel/model/associations.rb', line 3187

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.



3191
3192
3193
 
# File 'lib/sequel/model/associations.rb', line 3191

def records_map
  @records_map
end

#reflection_map ⇒ Object (readonly)

Hash with table alias symbol keys and AssociationReflection values



3194
3195
3196
 
# File 'lib/sequel/model/associations.rb', line 3194

def reflection_map
  @reflection_map
end

#row_procs ⇒ Object (readonly)

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



3197
3198
3199
 
# File 'lib/sequel/model/associations.rb', line 3197

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).



3202
3203
3204
 
# File 'lib/sequel/model/associations.rb', line 3202

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).



3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
 
# File 'lib/sequel/model/associations.rb', line 3307

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

  # 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
end