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.
Methods
Public Class
Public Instance
Attributes
| after_load_map | [R] |
Hash with table alias symbol keys and after_load hook values |
| alias_map | [R] |
Hash with table alias symbol keys and association name values |
| column_maps | [R] |
Hash with table alias symbol keys and subhash values mapping column_alias symbols to the symbol of the real name of the column |
| dependency_map | [R] |
Recursive hash with table alias symbol keys mapping to hashes with dependent table alias symbol keys. |
| limit_map | [R] |
Hash with table alias symbol keys and [limit, offset] values |
| master | [R] |
The table alias symbol for the primary model |
| primary_keys | [R] |
Hash with table alias symbol keys and primary key symbol values (or arrays of primary key symbols for composite key tables) |
| reciprocal_map | [R] |
Hash with table alias symbol keys and reciprocal association symbol values, used for setting reciprocals for one_to_many associations. |
| records_map | [R] |
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. |
| reflection_map | [R] |
Hash with table alias symbol keys and |
| row_procs | [R] |
Hash with table alias symbol keys and callable values used to create model instances |
| type_map | [R] |
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