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 3761 def initialize(dataset) 3762 opts = dataset.opts 3763 eager_graph = opts[:eager_graph] 3764 @master = eager_graph[:master] 3765 requirements = eager_graph[:requirements] 3766 reflection_map = @reflection_map = eager_graph[:reflections] 3767 reciprocal_map = @reciprocal_map = eager_graph[:reciprocals] 3768 limit_map = @limit_map = eager_graph[:limits] 3769 @unique = eager_graph[:cartesian_product_number] > 1 3770 3771 alias_map = @alias_map = {} 3772 type_map = @type_map = {} 3773 after_load_map = @after_load_map = {} 3774 reflection_map.each do |k, v| 3775 alias_map[k] = v[:name] 3776 after_load_map[k] = v[:after_load] if v[:after_load] 3777 type_map[k] = if v.returns_array? 3778 true 3779 elsif (limit_and_offset = limit_map[k]) && !limit_and_offset.last.nil? 3780 :offset 3781 end 3782 end 3783 after_load_map.freeze 3784 alias_map.freeze 3785 type_map.freeze 3786 3787 # Make dependency map hash out of requirements array for each association. 3788 # This builds a tree of dependencies that will be used for recursion 3789 # to ensure that all parts of the object graph are loaded into the 3790 # appropriate subordinate association. 3791 dependency_map = @dependency_map = {} 3792 # Sort the associations by requirements length, so that 3793 # requirements are added to the dependency hash before their 3794 # dependencies. 3795 requirements.sort_by{|a| a[1].length}.each do |ta, deps| 3796 if deps.empty? 3797 dependency_map[ta] = {} 3798 else 3799 deps = deps.dup 3800 hash = dependency_map[deps.shift] 3801 deps.each do |dep| 3802 hash = hash[dep] 3803 end 3804 hash[ta] = {} 3805 end 3806 end 3807 freezer = lambda do |h| 3808 h.freeze 3809 h.each_value(&freezer) 3810 end 3811 freezer.call(dependency_map) 3812 3813 datasets = opts[:graph][:table_aliases].to_a.reject{|ta,ds| ds.nil?} 3814 column_aliases = opts[:graph][:column_aliases] 3815 primary_keys = {} 3816 column_maps = {} 3817 models = {} 3818 row_procs = {} 3819 datasets.each do |ta, ds| 3820 models[ta] = ds.model 3821 primary_keys[ta] = [] 3822 column_maps[ta] = {} 3823 row_procs[ta] = ds.row_proc 3824 end 3825 column_aliases.each do |col_alias, tc| 3826 ta, column = tc 3827 column_maps[ta][col_alias] = column 3828 end 3829 column_maps.each do |ta, h| 3830 pk = models[ta].primary_key 3831 if pk.is_a?(Array) 3832 primary_keys[ta] = [] 3833 h.select{|ca, c| primary_keys[ta] << ca if pk.include?(c)} 3834 else 3835 h.select{|ca, c| primary_keys[ta] = ca if pk == c} 3836 end 3837 end 3838 @column_maps = column_maps.freeze 3839 @primary_keys = primary_keys.freeze 3840 @row_procs = row_procs.freeze 3841 3842 # For performance, create two special maps for the master table, 3843 # so you can skip a hash lookup. 3844 @master_column_map = column_maps[master] 3845 @master_primary_keys = primary_keys[master] 3846 3847 # Add a special hash mapping table alias symbols to 5 element arrays that just 3848 # contain the data in other data structures for that table alias. This is 3849 # used for performance, to get all values in one hash lookup instead of 3850 # separate hash lookups for each data structure. 3851 ta_map = {} 3852 alias_map.each_key do |ta| 3853 ta_map[ta] = [row_procs[ta], alias_map[ta], type_map[ta], reciprocal_map[ta]].freeze 3854 end 3855 @ta_map = ta_map.freeze 3856 freeze 3857 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 3861 def load(hashes) 3862 # This mapping is used to make sure that duplicate entries in the 3863 # result set are mapped to a single record. For example, using a 3864 # single one_to_many association with 10 associated records, 3865 # the main object column values appear in the object graph 10 times. 3866 # We map by primary key, if available, or by the object's entire values, 3867 # if not. The mapping must be per table, so create sub maps for each table 3868 # alias. 3869 @records_map = records_map = {} 3870 alias_map.keys.each{|ta| records_map[ta] = {}} 3871 3872 master = master() 3873 3874 # Assign to local variables for speed increase 3875 rp = row_procs[master] 3876 rm = records_map[master] = {} 3877 dm = dependency_map 3878 3879 records_map.freeze 3880 3881 # This will hold the final record set that we will be replacing the object graph with. 3882 records = [] 3883 3884 hashes.each do |h| 3885 unless key = master_pk(h) 3886 key = hkey(master_hfor(h)) 3887 end 3888 unless primary_record = rm[key] 3889 primary_record = rm[key] = rp.call(master_hfor(h)) 3890 # Only add it to the list of records to return if it is a new record 3891 records.push(primary_record) 3892 end 3893 # Build all associations for the current object and it's dependencies 3894 _load(dm, primary_record, h) 3895 end 3896 3897 # Remove duplicate records from all associations if this graph could possibly be a cartesian product 3898 # Run after_load procs if there are any 3899 post_process(records, dm) if @unique || !after_load_map.empty? || !limit_map.empty? 3900 3901 records_map.each_value(&:freeze) 3902 freeze 3903 3904 records 3905 end