Class | Sequel::Model::Associations::EagerGraphLoader |
In: |
lib/sequel/model/associations.rb
|
Parent: | Object |
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.
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] | Hash with table alias symbol keys and callable values used to create model instances 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 AssociationReflection values |
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). |
Initialize all of the data structures used during loading.
# File lib/sequel/model/associations.rb, line 2023 2023: def initialize(dataset) 2024: opts = dataset.opts 2025: eager_graph = opts[:eager_graph] 2026: @master = eager_graph[:master] 2027: requirements = eager_graph[:requirements] 2028: reflection_map = @reflection_map = eager_graph[:reflections] 2029: reciprocal_map = @reciprocal_map = eager_graph[:reciprocals] 2030: @unique = eager_graph[:cartesian_product_number] > 1 2031: 2032: alias_map = @alias_map = {} 2033: type_map = @type_map = {} 2034: after_load_map = @after_load_map = {} 2035: limit_map = @limit_map = {} 2036: reflection_map.each do |k, v| 2037: alias_map[k] = v[:name] 2038: type_map[k] = v.returns_array? 2039: after_load_map[k] = v[:after_load] unless v[:after_load].empty? 2040: limit_map[k] = v.limit_and_offset if v[:limit] 2041: end 2042: 2043: # Make dependency map hash out of requirements array for each association. 2044: # This builds a tree of dependencies that will be used for recursion 2045: # to ensure that all parts of the object graph are loaded into the 2046: # appropriate subordinate association. 2047: @dependency_map = {} 2048: # Sort the associations by requirements length, so that 2049: # requirements are added to the dependency hash before their 2050: # dependencies. 2051: requirements.sort_by{|a| a[1].length}.each do |ta, deps| 2052: if deps.empty? 2053: dependency_map[ta] = {} 2054: else 2055: deps = deps.dup 2056: hash = dependency_map[deps.shift] 2057: deps.each do |dep| 2058: hash = hash[dep] 2059: end 2060: hash[ta] = {} 2061: end 2062: end 2063: 2064: # This mapping is used to make sure that duplicate entries in the 2065: # result set are mapped to a single record. For example, using a 2066: # single one_to_many association with 10 associated records, 2067: # the main object column values appear in the object graph 10 times. 2068: # We map by primary key, if available, or by the object's entire values, 2069: # if not. The mapping must be per table, so create sub maps for each table 2070: # alias. 2071: records_map = {@master=>{}} 2072: alias_map.keys.each{|ta| records_map[ta] = {}} 2073: @records_map = records_map 2074: 2075: datasets = opts[:graph][:table_aliases].to_a.reject{|ta,ds| ds.nil?} 2076: column_aliases = opts[:graph_aliases] || opts[:graph][:column_aliases] 2077: primary_keys = {} 2078: column_maps = {} 2079: models = {} 2080: row_procs = {} 2081: datasets.each do |ta, ds| 2082: models[ta] = ds.model 2083: primary_keys[ta] = [] 2084: column_maps[ta] = {} 2085: row_procs[ta] = ds.row_proc 2086: end 2087: column_aliases.each do |col_alias, tc| 2088: ta, column = tc 2089: column_maps[ta][col_alias] = column 2090: end 2091: column_maps.each do |ta, h| 2092: pk = models[ta].primary_key 2093: if pk.is_a?(Array) 2094: primary_keys[ta] = [] 2095: h.select{|ca, c| primary_keys[ta] << ca if pk.include?(c)} 2096: else 2097: h.select{|ca, c| primary_keys[ta] = ca if pk == c} 2098: end 2099: end 2100: @column_maps = column_maps 2101: @primary_keys = primary_keys 2102: @row_procs = row_procs 2103: 2104: # For performance, create two special maps for the master table, 2105: # so you can skip a hash lookup. 2106: @master_column_map = column_maps[master] 2107: @master_primary_keys = primary_keys[master] 2108: 2109: # Add a special hash mapping table alias symbols to 5 element arrays that just 2110: # contain the data in other data structures for that table alias. This is 2111: # used for performance, to get all values in one hash lookup instead of 2112: # separate hash lookups for each data structure. 2113: ta_map = {} 2114: alias_map.keys.each do |ta| 2115: ta_map[ta] = [records_map[ta], row_procs[ta], alias_map[ta], type_map[ta], reciprocal_map[ta]] 2116: end 2117: @ta_map = ta_map 2118: end
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, line 2122 2122: def load(hashes) 2123: master = master() 2124: 2125: # Assign to local variables for speed increase 2126: rp = row_procs[master] 2127: rm = records_map[master] 2128: dm = dependency_map 2129: 2130: # This will hold the final record set that we will be replacing the object graph with. 2131: records = [] 2132: 2133: hashes.each do |h| 2134: unless key = master_pk(h) 2135: key = hkey(master_hfor(h)) 2136: end 2137: unless primary_record = rm[key] 2138: primary_record = rm[key] = rp.call(master_hfor(h)) 2139: # Only add it to the list of records to return if it is a new record 2140: records.push(primary_record) 2141: end 2142: # Build all associations for the current object and it's dependencies 2143: _load(dm, primary_record, h) 2144: end 2145: 2146: # Remove duplicate records from all associations if this graph could possibly be a cartesian product 2147: # Run after_load procs if there are any 2148: post_process(records, dm) if @unique || !after_load_map.empty? || !limit_map.empty? 2149: 2150: records 2151: end