class Sequel::Model::Associations::EagerGraphLoader
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.
Attributes
Hash
with table alias symbol keys and after_load hook values
Hash
with table alias symbol keys and association name values
Hash
with table alias symbol keys and subhash values mapping column_alias symbols to the symbol of the real name of the column
Recursive hash with table alias symbol keys mapping to hashes with dependent table alias symbol keys.
Hash
with table alias symbol keys and [limit, offset] values
The table alias symbol for the primary model
Hash
with table alias symbol keys and primary key symbol values (or arrays of primary key symbols for composite key tables)
Hash
with table alias symbol keys and reciprocal association symbol values, used for setting reciprocals for one_to_many associations.
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.
Hash
with table alias symbol keys and AssociationReflection
values
Hash
with table alias symbol keys and callable values used to create model instances
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).
Public Class Methods
Initialize all of the data structures used during loading.
# File lib/sequel/model/associations.rb 3768 def initialize(dataset) 3769 opts = dataset.opts 3770 eager_graph = opts[:eager_graph] 3771 @master = eager_graph[:master] 3772 requirements = eager_graph[:requirements] 3773 reflection_map = @reflection_map = eager_graph[:reflections] 3774 reciprocal_map = @reciprocal_map = eager_graph[:reciprocals] 3775 limit_map = @limit_map = eager_graph[:limits] 3776 @unique = eager_graph[:cartesian_product_number] > 1 3777 3778 alias_map = @alias_map = {} 3779 type_map = @type_map = {} 3780 after_load_map = @after_load_map = {} 3781 reflection_map.each do |k, v| 3782 alias_map[k] = v[:name] 3783 after_load_map[k] = v[:after_load] if v[:after_load] 3784 type_map[k] = if v.returns_array? 3785 true 3786 elsif (limit_and_offset = limit_map[k]) && !limit_and_offset.last.nil? 3787 :offset 3788 end 3789 end 3790 after_load_map.freeze 3791 alias_map.freeze 3792 type_map.freeze 3793 3794 # Make dependency map hash out of requirements array for each association. 3795 # This builds a tree of dependencies that will be used for recursion 3796 # to ensure that all parts of the object graph are loaded into the 3797 # appropriate subordinate association. 3798 dependency_map = @dependency_map = {} 3799 # Sort the associations by requirements length, so that 3800 # requirements are added to the dependency hash before their 3801 # dependencies. 3802 requirements.sort_by{|a| a[1].length}.each do |ta, deps| 3803 if deps.empty? 3804 dependency_map[ta] = {} 3805 else 3806 deps = deps.dup 3807 hash = dependency_map[deps.shift] 3808 deps.each do |dep| 3809 hash = hash[dep] 3810 end 3811 hash[ta] = {} 3812 end 3813 end 3814 freezer = lambda do |h| 3815 h.freeze 3816 h.each_value(&freezer) 3817 end 3818 freezer.call(dependency_map) 3819 3820 datasets = opts[:graph][:table_aliases].to_a.reject{|ta,ds| ds.nil?} 3821 column_aliases = opts[:graph][:column_aliases] 3822 primary_keys = {} 3823 column_maps = {} 3824 models = {} 3825 row_procs = {} 3826 datasets.each do |ta, ds| 3827 models[ta] = ds.model 3828 primary_keys[ta] = [] 3829 column_maps[ta] = {} 3830 row_procs[ta] = ds.row_proc 3831 end 3832 column_aliases.each do |col_alias, tc| 3833 ta, column = tc 3834 column_maps[ta][col_alias] = column 3835 end 3836 column_maps.each do |ta, h| 3837 pk = models[ta].primary_key 3838 if pk.is_a?(Array) 3839 primary_keys[ta] = [] 3840 h.select{|ca, c| primary_keys[ta] << ca if pk.include?(c)} 3841 else 3842 h.select{|ca, c| primary_keys[ta] = ca if pk == c} 3843 end 3844 end 3845 @column_maps = column_maps.freeze 3846 @primary_keys = primary_keys.freeze 3847 @row_procs = row_procs.freeze 3848 3849 # For performance, create two special maps for the master table, 3850 # so you can skip a hash lookup. 3851 @master_column_map = column_maps[master] 3852 @master_primary_keys = primary_keys[master] 3853 3854 # Add a special hash mapping table alias symbols to 5 element arrays that just 3855 # contain the data in other data structures for that table alias. This is 3856 # used for performance, to get all values in one hash lookup instead of 3857 # separate hash lookups for each data structure. 3858 ta_map = {} 3859 alias_map.each_key do |ta| 3860 ta_map[ta] = [row_procs[ta], alias_map[ta], type_map[ta], reciprocal_map[ta]].freeze 3861 end 3862 @ta_map = ta_map.freeze 3863 freeze 3864 end
Public Instance Methods
Return an array of primary model instances with the associations cache prepopulated for all model objects (both primary and associated).
# File lib/sequel/model/associations.rb 3868 def load(hashes) 3869 # This mapping is used to make sure that duplicate entries in the 3870 # result set are mapped to a single record. For example, using a 3871 # single one_to_many association with 10 associated records, 3872 # the main object column values appear in the object graph 10 times. 3873 # We map by primary key, if available, or by the object's entire values, 3874 # if not. The mapping must be per table, so create sub maps for each table 3875 # alias. 3876 @records_map = records_map = {} 3877 alias_map.keys.each{|ta| records_map[ta] = {}} 3878 3879 master = master() 3880 3881 # Assign to local variables for speed increase 3882 rp = row_procs[master] 3883 rm = records_map[master] = {} 3884 dm = dependency_map 3885 3886 records_map.freeze 3887 3888 # This will hold the final record set that we will be replacing the object graph with. 3889 records = [] 3890 3891 hashes.each do |h| 3892 unless key = master_pk(h) 3893 key = hkey(master_hfor(h)) 3894 end 3895 unless primary_record = rm[key] 3896 primary_record = rm[key] = rp.call(master_hfor(h)) 3897 # Only add it to the list of records to return if it is a new record 3898 records.push(primary_record) 3899 end 3900 # Build all associations for the current object and it's dependencies 3901 _load(dm, primary_record, h) 3902 end 3903 3904 # Remove duplicate records from all associations if this graph could possibly be a cartesian product 3905 # Run after_load procs if there are any 3906 post_process(records, dm) if @unique || !after_load_map.empty? || !limit_map.empty? 3907 3908 records_map.each_value(&:freeze) 3909 freeze 3910 3911 records 3912 end