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 2196 2196: def initialize(dataset) 2197: opts = dataset.opts 2198: eager_graph = opts[:eager_graph] 2199: @master = eager_graph[:master] 2200: requirements = eager_graph[:requirements] 2201: reflection_map = @reflection_map = eager_graph[:reflections] 2202: reciprocal_map = @reciprocal_map = eager_graph[:reciprocals] 2203: @unique = eager_graph[:cartesian_product_number] > 1 2204: 2205: alias_map = @alias_map = {} 2206: type_map = @type_map = {} 2207: after_load_map = @after_load_map = {} 2208: limit_map = @limit_map = {} 2209: reflection_map.each do |k, v| 2210: alias_map[k] = v[:name] 2211: type_map[k] = v.returns_array? 2212: after_load_map[k] = v[:after_load] unless v[:after_load].empty? 2213: limit_map[k] = v.limit_and_offset if v[:limit] 2214: end 2215: 2216: # Make dependency map hash out of requirements array for each association. 2217: # This builds a tree of dependencies that will be used for recursion 2218: # to ensure that all parts of the object graph are loaded into the 2219: # appropriate subordinate association. 2220: @dependency_map = {} 2221: # Sort the associations by requirements length, so that 2222: # requirements are added to the dependency hash before their 2223: # dependencies. 2224: requirements.sort_by{|a| a[1].length}.each do |ta, deps| 2225: if deps.empty? 2226: dependency_map[ta] = {} 2227: else 2228: deps = deps.dup 2229: hash = dependency_map[deps.shift] 2230: deps.each do |dep| 2231: hash = hash[dep] 2232: end 2233: hash[ta] = {} 2234: end 2235: end 2236: 2237: # This mapping is used to make sure that duplicate entries in the 2238: # result set are mapped to a single record. For example, using a 2239: # single one_to_many association with 10 associated records, 2240: # the main object column values appear in the object graph 10 times. 2241: # We map by primary key, if available, or by the object's entire values, 2242: # if not. The mapping must be per table, so create sub maps for each table 2243: # alias. 2244: records_map = {@master=>{}} 2245: alias_map.keys.each{|ta| records_map[ta] = {}} 2246: @records_map = records_map 2247: 2248: datasets = opts[:graph][:table_aliases].to_a.reject{|ta,ds| ds.nil?} 2249: column_aliases = opts[:graph_aliases] || opts[:graph][:column_aliases] 2250: primary_keys = {} 2251: column_maps = {} 2252: models = {} 2253: row_procs = {} 2254: datasets.each do |ta, ds| 2255: models[ta] = ds.model 2256: primary_keys[ta] = [] 2257: column_maps[ta] = {} 2258: row_procs[ta] = ds.row_proc 2259: end 2260: column_aliases.each do |col_alias, tc| 2261: ta, column = tc 2262: column_maps[ta][col_alias] = column 2263: end 2264: column_maps.each do |ta, h| 2265: pk = models[ta].primary_key 2266: if pk.is_a?(Array) 2267: primary_keys[ta] = [] 2268: h.select{|ca, c| primary_keys[ta] << ca if pk.include?(c)} 2269: else 2270: h.select{|ca, c| primary_keys[ta] = ca if pk == c} 2271: end 2272: end 2273: @column_maps = column_maps 2274: @primary_keys = primary_keys 2275: @row_procs = row_procs 2276: 2277: # For performance, create two special maps for the master table, 2278: # so you can skip a hash lookup. 2279: @master_column_map = column_maps[master] 2280: @master_primary_keys = primary_keys[master] 2281: 2282: # Add a special hash mapping table alias symbols to 5 element arrays that just 2283: # contain the data in other data structures for that table alias. This is 2284: # used for performance, to get all values in one hash lookup instead of 2285: # separate hash lookups for each data structure. 2286: ta_map = {} 2287: alias_map.keys.each do |ta| 2288: ta_map[ta] = [records_map[ta], row_procs[ta], alias_map[ta], type_map[ta], reciprocal_map[ta]] 2289: end 2290: @ta_map = ta_map 2291: 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 2295 2295: def load(hashes) 2296: master = master() 2297: 2298: # Assign to local variables for speed increase 2299: rp = row_procs[master] 2300: rm = records_map[master] 2301: dm = dependency_map 2302: 2303: # This will hold the final record set that we will be replacing the object graph with. 2304: records = [] 2305: 2306: hashes.each do |h| 2307: unless key = master_pk(h) 2308: key = hkey(master_hfor(h)) 2309: end 2310: unless primary_record = rm[key] 2311: primary_record = rm[key] = rp.call(master_hfor(h)) 2312: # Only add it to the list of records to return if it is a new record 2313: records.push(primary_record) 2314: end 2315: # Build all associations for the current object and it's dependencies 2316: _load(dm, primary_record, h) 2317: end 2318: 2319: # Remove duplicate records from all associations if this graph could possibly be a cartesian product 2320: # Run after_load procs if there are any 2321: post_process(records, dm) if @unique || !after_load_map.empty? || !limit_map.empty? 2322: 2323: records 2324: end