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 3043 3043: def initialize(dataset) 3044: opts = dataset.opts 3045: eager_graph = opts[:eager_graph] 3046: @master = eager_graph[:master] 3047: requirements = eager_graph[:requirements] 3048: reflection_map = @reflection_map = eager_graph[:reflections] 3049: reciprocal_map = @reciprocal_map = eager_graph[:reciprocals] 3050: limit_map = @limit_map = eager_graph[:limits] 3051: @unique = eager_graph[:cartesian_product_number] > 1 3052: 3053: alias_map = @alias_map = {} 3054: type_map = @type_map = {} 3055: after_load_map = @after_load_map = {} 3056: reflection_map.each do |k, v| 3057: alias_map[k] = v[:name] 3058: after_load_map[k] = v[:after_load] unless v[:after_load].empty? 3059: type_map[k] = if v.returns_array? 3060: true 3061: elsif (limit_and_offset = limit_map[k]) && !limit_and_offset.last.nil? 3062: :offset 3063: end 3064: end 3065: 3066: # Make dependency map hash out of requirements array for each association. 3067: # This builds a tree of dependencies that will be used for recursion 3068: # to ensure that all parts of the object graph are loaded into the 3069: # appropriate subordinate association. 3070: @dependency_map = {} 3071: # Sort the associations by requirements length, so that 3072: # requirements are added to the dependency hash before their 3073: # dependencies. 3074: requirements.sort_by{|a| a[1].length}.each do |ta, deps| 3075: if deps.empty? 3076: dependency_map[ta] = {} 3077: else 3078: deps = deps.dup 3079: hash = dependency_map[deps.shift] 3080: deps.each do |dep| 3081: hash = hash[dep] 3082: end 3083: hash[ta] = {} 3084: end 3085: end 3086: 3087: # This mapping is used to make sure that duplicate entries in the 3088: # result set are mapped to a single record. For example, using a 3089: # single one_to_many association with 10 associated records, 3090: # the main object column values appear in the object graph 10 times. 3091: # We map by primary key, if available, or by the object's entire values, 3092: # if not. The mapping must be per table, so create sub maps for each table 3093: # alias. 3094: records_map = {@master=>{}} 3095: alias_map.keys.each{|ta| records_map[ta] = {}} 3096: @records_map = records_map 3097: 3098: datasets = opts[:graph][:table_aliases].to_a.reject{|ta,ds| ds.nil?} 3099: column_aliases = opts[:graph_aliases] || opts[:graph][:column_aliases] 3100: primary_keys = {} 3101: column_maps = {} 3102: models = {} 3103: row_procs = {} 3104: datasets.each do |ta, ds| 3105: models[ta] = ds.model 3106: primary_keys[ta] = [] 3107: column_maps[ta] = {} 3108: row_procs[ta] = ds.row_proc 3109: end 3110: column_aliases.each do |col_alias, tc| 3111: ta, column = tc 3112: column_maps[ta][col_alias] = column 3113: end 3114: column_maps.each do |ta, h| 3115: pk = models[ta].primary_key 3116: if pk.is_a?(Array) 3117: primary_keys[ta] = [] 3118: h.select{|ca, c| primary_keys[ta] << ca if pk.include?(c)} 3119: else 3120: h.select{|ca, c| primary_keys[ta] = ca if pk == c} 3121: end 3122: end 3123: @column_maps = column_maps 3124: @primary_keys = primary_keys 3125: @row_procs = row_procs 3126: 3127: # For performance, create two special maps for the master table, 3128: # so you can skip a hash lookup. 3129: @master_column_map = column_maps[master] 3130: @master_primary_keys = primary_keys[master] 3131: 3132: # Add a special hash mapping table alias symbols to 5 element arrays that just 3133: # contain the data in other data structures for that table alias. This is 3134: # used for performance, to get all values in one hash lookup instead of 3135: # separate hash lookups for each data structure. 3136: ta_map = {} 3137: alias_map.keys.each do |ta| 3138: ta_map[ta] = [records_map[ta], row_procs[ta], alias_map[ta], type_map[ta], reciprocal_map[ta]] 3139: end 3140: @ta_map = ta_map 3141: 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 3145 3145: def load(hashes) 3146: master = master() 3147: 3148: # Assign to local variables for speed increase 3149: rp = row_procs[master] 3150: rm = records_map[master] 3151: dm = dependency_map 3152: 3153: # This will hold the final record set that we will be replacing the object graph with. 3154: records = [] 3155: 3156: hashes.each do |h| 3157: unless key = master_pk(h) 3158: key = hkey(master_hfor(h)) 3159: end 3160: unless primary_record = rm[key] 3161: primary_record = rm[key] = rp.call(master_hfor(h)) 3162: # Only add it to the list of records to return if it is a new record 3163: records.push(primary_record) 3164: end 3165: # Build all associations for the current object and it's dependencies 3166: _load(dm, primary_record, h) 3167: end 3168: 3169: # Remove duplicate records from all associations if this graph could possibly be a cartesian product 3170: # Run after_load procs if there are any 3171: post_process(records, dm) if @unique || !after_load_map.empty? || !limit_map.empty? 3172: 3173: records 3174: end