module Sequel::Model::Associations::DatasetMethods
Eager loading makes it so that you can load all associated records for a set of objects in a single query, instead of a separate query for each object.
Two separate implementations are provided. eager
should be used most of the time, as it loads associated records using one query per association. However, it does not allow you the ability to filter or order based on columns in associated tables. eager_graph
loads all records in a single query using JOINs, allowing you to filter or order based on columns in associated tables. However, eager_graph
is usually slower than eager
, especially if multiple one_to_many or many_to_many associations are joined.
You can cascade the eager loading (loading associations on associated objects) with no limit to the depth of the cascades. You do this by passing a hash to eager
or eager_graph
with the keys being associations of the current model and values being associations of the model associated with the current model via the key.
The arguments can be symbols or hashes with symbol keys (for cascaded eager loading). Examples:
Album.eager(:artist).all Album.eager_graph(:artist).all Album.eager(:artist, :genre).all Album.eager_graph(:artist, :genre).all Album.eager(:artist).eager(:genre).all Album.eager_graph(:artist).eager_graph(:genre).all Artist.eager(albums: :tracks).all Artist.eager_graph(albums: :tracks).all Artist.eager(albums: {tracks: :genre}).all Artist.eager_graph(albums: {tracks: :genre}).all
You can also pass a callback as a hash value in order to customize the dataset being eager loaded at query time, analogous to the way the :eager_block association option allows you to customize it at association definition time. For example, if you wanted artists with their albums since 1990:
Artist.eager(albums: proc{|ds| ds.where{year > 1990}})
Or if you needed albums and their artist's name only, using a single query:
Albums.eager_graph(artist: proc{|ds| ds.select(:name)})
To cascade eager loading while using a callback, you substitute the cascaded associations with a single entry hash that has the proc callback as the key and the cascaded associations as the value. This will load artists with their albums since 1990, and also the tracks on those albums and the genre for those tracks:
Artist.eager(albums: {proc{|ds| ds.where{year > 1990}}=>{tracks: :genre}})
Public Instance Methods
If the dataset is being eagerly loaded, default to calling all instead of each.
# File lib/sequel/model/associations.rb 3110 def as_hash(key_column=nil, value_column=nil, opts=OPTS) 3111 if (@opts[:eager_graph] || @opts[:eager]) && !opts.has_key?(:all) 3112 opts = Hash[opts] 3113 opts[:all] = true 3114 end 3115 super 3116 end
Adds one or more INNER JOINs to the existing dataset using the keys and conditions specified by the given association(s). Take the same arguments as eager_graph
, and operates similarly, but only adds the joins as opposed to making the other changes (such as adding selected columns and setting up eager loading).
The following methods also exist for specifying a different type of JOIN:
- association_full_join
-
FULL JOIN
- association_inner_join
-
INNER JOIN
- association_left_join
-
LEFT JOIN
- association_right_join
-
RIGHT JOIN
Examples:
# For each album, association_join load the artist Album.association_join(:artist).all # SELECT * # FROM albums # INNER JOIN artists AS artist ON (artists.id = albums.artist_id) # For each album, association_join load the artist, using a specified alias Album.association_join(Sequel[:artist].as(:a)).all # SELECT * # FROM albums # INNER JOIN artists AS a ON (a.id = albums.artist_id) # For each album, association_join load the artist and genre Album.association_join(:artist, :genre).all Album.association_join(:artist).association_join(:genre).all # SELECT * # FROM albums # INNER JOIN artists AS artist ON (artist.id = albums.artist_id) # INNER JOIN genres AS genre ON (genre.id = albums.genre_id) # For each artist, association_join load albums and tracks for each album Artist.association_join(albums: :tracks).all # SELECT * # FROM artists # INNER JOIN albums ON (albums.artist_id = artists.id) # INNER JOIN tracks ON (tracks.album_id = albums.id) # For each artist, association_join load albums, tracks for each album, and genre for each track Artist.association_join(albums: {tracks: :genre}).all # SELECT * # FROM artists # INNER JOIN albums ON (albums.artist_id = artists.id) # INNER JOIN tracks ON (tracks.album_id = albums.id) # INNER JOIN genres AS genre ON (genre.id = tracks.genre_id) # For each artist, association_join load albums with year > 1990 Artist.association_join(albums: proc{|ds| ds.where{year > 1990}}).all # SELECT * # FROM artists # INNER JOIN ( # SELECT * FROM albums WHERE (year > 1990) # ) AS albums ON (albums.artist_id = artists.id) # For each artist, association_join load albums and tracks 1-10 for each album Artist.association_join(albums: {tracks: proc{|ds| ds.where(number: 1..10)}}).all # SELECT * # FROM artists # INNER JOIN albums ON (albums.artist_id = artists.id) # INNER JOIN ( # SELECT * FROM tracks WHERE ((number >= 1) AND (number <= 10)) # ) AS tracks ON (tracks.albums_id = albums.id) # For each artist, association_join load albums with year > 1990, and tracks for those albums Artist.association_join(albums: {proc{|ds| ds.where{year > 1990}}=>:tracks}).all # SELECT * # FROM artists # INNER JOIN ( # SELECT * FROM albums WHERE (year > 1990) # ) AS albums ON (albums.artist_id = artists.id) # INNER JOIN tracks ON (tracks.album_id = albums.id)
# File lib/sequel/model/associations.rb 2820 def association_join(*associations) 2821 association_inner_join(*associations) 2822 end
If the expression is in the form x = y
where y
is a Sequel::Model
instance, array of Sequel::Model
instances, or a Sequel::Model
dataset, assume x
is an association symbol and look up the association reflection via the dataset's model. From there, return the appropriate SQL
based on the type of association and the values of the foreign/primary keys of y
. For most association types, this is a simple transformation, but for many_to_many
associations this creates a subquery to the join table.
# File lib/sequel/model/associations.rb 2831 def complex_expression_sql_append(sql, op, args) 2832 r = args[1] 2833 if (((op == :'=' || op == :'!=') && r.is_a?(Sequel::Model)) || 2834 (multiple = ((op == :IN || op == :'NOT IN') && ((is_ds = r.is_a?(Sequel::Dataset)) || (r.respond_to?(:all?) && r.all?{|x| x.is_a?(Sequel::Model)}))))) 2835 l = args[0] 2836 if ar = model.association_reflections[l] 2837 if multiple 2838 klass = ar.associated_class 2839 if is_ds 2840 if r.respond_to?(:model) 2841 unless r.model <= klass 2842 # A dataset for a different model class, could be a valid regular query 2843 return super 2844 end 2845 else 2846 # Not a model dataset, could be a valid regular query 2847 return super 2848 end 2849 else 2850 unless r.all?{|x| x.is_a?(klass)} 2851 raise Sequel::Error, "invalid association class for one object for association #{l.inspect} used in dataset filter for model #{model.inspect}, expected class #{klass.inspect}" 2852 end 2853 end 2854 elsif !r.is_a?(ar.associated_class) 2855 raise Sequel::Error, "invalid association class #{r.class.inspect} for association #{l.inspect} used in dataset filter for model #{model.inspect}, expected class #{ar.associated_class.inspect}" 2856 end 2857 2858 if exp = association_filter_expression(op, ar, r) 2859 literal_append(sql, exp) 2860 else 2861 raise Sequel::Error, "invalid association type #{ar[:type].inspect} for association #{l.inspect} used in dataset filter for model #{model.inspect}" 2862 end 2863 elsif multiple && (is_ds || r.empty?) 2864 # Not a query designed for this support, could be a valid regular query 2865 super 2866 else 2867 raise Sequel::Error, "invalid association #{l.inspect} used in dataset filter for model #{model.inspect}" 2868 end 2869 else 2870 super 2871 end 2872 end
The preferred eager loading method. Loads all associated records using one query for each association.
The basic idea for how it works is that the dataset is first loaded normally. Then it goes through all associations that have been specified via eager
. It loads each of those associations separately, then associates them back to the original dataset via primary/foreign keys. Due to the necessity of all objects being present, you need to use all
to use eager loading, as it can't work with each
.
This implementation avoids the complexity of extracting an object graph out of a single dataset, by building the object graph out of multiple datasets, one for each association. By using a separate dataset for each association, it avoids problems such as aliasing conflicts and creating cartesian product result sets if multiple one_to_many or many_to_many eager associations are requested.
One limitation of using this method is that you cannot filter the current dataset based on values of columns in an associated table, since the associations are loaded in separate queries. To do that you need to load all associations in the same query, and extract an object graph from the results of that query. If you need to filter based on columns in associated tables, look at eager_graph
or join the tables you need to filter on manually.
Each association's order, if defined, is respected. If the association uses a block or has an :eager_block argument, it is used.
To modify the associated dataset that will be used for the eager load, you should use a hash for the association, with the key being the association name symbol, and the value being a callable object that is called with the associated dataset and should return a modified dataset. If that association also has dependent associations, instead of a callable object, use a hash with the callable object being the key, and the dependent association(s) as the value.
Examples:
# For each album, eager load the artist Album.eager(:artist).all # SELECT * FROM albums # SELECT * FROM artists WHERE (id IN (...)) # For each album, eager load the artist and genre Album.eager(:artist, :genre).all Album.eager(:artist).eager(:genre).all # SELECT * FROM albums # SELECT * FROM artists WHERE (id IN (...)) # SELECT * FROM genres WHERE (id IN (...)) # For each artist, eager load albums and tracks for each album Artist.eager(albums: :tracks).all # SELECT * FROM artists # SELECT * FROM albums WHERE (artist_id IN (...)) # SELECT * FROM tracks WHERE (album_id IN (...)) # For each artist, eager load albums, tracks for each album, and genre for each track Artist.eager(albums: {tracks: :genre}).all # SELECT * FROM artists # SELECT * FROM albums WHERE (artist_id IN (...)) # SELECT * FROM tracks WHERE (album_id IN (...)) # SELECT * FROM genre WHERE (id IN (...)) # For each artist, eager load albums with year > 1990 Artist.eager(albums: proc{|ds| ds.where{year > 1990}}).all # SELECT * FROM artists # SELECT * FROM albums WHERE ((year > 1990) AND (artist_id IN (...))) # For each artist, eager load albums and tracks 1-10 for each album Artist.eager(albums: {tracks: proc{|ds| ds.where(number: 1..10)}}).all # SELECT * FROM artists # SELECT * FROM albums WHERE (artist_id IN (...)) # SELECT * FROM tracks WHERE ((number >= 1) AND (number <= 10) AND (album_id IN (...))) # For each artist, eager load albums with year > 1990, and tracks for those albums Artist.eager(albums: {proc{|ds| ds.where{year > 1990}}=>:tracks}).all # SELECT * FROM artists # SELECT * FROM albums WHERE ((year > 1990) AND (artist_id IN (...))) # SELECT * FROM albums WHERE (artist_id IN (...))
# File lib/sequel/model/associations.rb 2949 def eager(*associations) 2950 opts = @opts[:eager] 2951 association_opts = eager_options_for_associations(associations) 2952 opts = opts ? opts.merge(association_opts) : association_opts 2953 clone(:eager=>opts.freeze) 2954 end
The secondary eager loading method. Loads all associations in a single query. This method should only be used if you need to filter or order based on columns in associated tables, or if you have done comparative benchmarking it and determined it is faster.
This method uses Dataset#graph
to create appropriate aliases for columns in all the tables. Then it uses the graph's metadata to build the associations from the single hash, and finally replaces the array of hashes with an array model objects inside all.
Be very careful when using this with multiple one_to_many or many_to_many associations, as you can create large cartesian products. If you must graph multiple one_to_many and many_to_many associations, make sure your filters are narrow if the datasets are large.
Each association's order, if defined, is respected. eager_graph
probably won't work correctly on a limited dataset, unless you are only graphing many_to_one, one_to_one, and one_through_one associations.
Does not use the block defined for the association, since it does a single query for all objects. You can use the :graph_* association options to modify the SQL
query.
Like eager
, you need to call all
on the dataset for the eager loading to work. If you just call each
, it will yield plain hashes, each containing all columns from all the tables.
To modify the associated dataset that will be joined to the current dataset, you should use a hash for the association, with the key being the association name symbol, and the value being a callable object that is called with the associated dataset and should return a modified dataset. If that association also has dependent associations, instead of a callable object, use a hash with the callable object being the key, and the dependent association(s) as the value.
You can specify an custom alias and/or join type on a per-association basis by providing an Sequel::SQL::AliasedExpression
object instead of an a Symbol
for the association name.
Examples:
# For each album, eager_graph load the artist Album.eager_graph(:artist).all # SELECT ... # FROM albums # LEFT OUTER JOIN artists AS artist ON (artists.id = albums.artist_id) # For each album, eager_graph load the artist, using a specified alias Album.eager_graph(Sequel[:artist].as(:a)).all # SELECT ... # FROM albums # LEFT OUTER JOIN artists AS a ON (a.id = albums.artist_id) # For each album, eager_graph load the artist, using a specified alias # and custom join type Album.eager_graph(Sequel[:artist].as(:a, join_type: :inner)).all # SELECT ... # FROM albums # INNER JOIN artists AS a ON (a.id = albums.artist_id) # For each album, eager_graph load the artist and genre Album.eager_graph(:artist, :genre).all Album.eager_graph(:artist).eager_graph(:genre).all # SELECT ... # FROM albums # LEFT OUTER JOIN artists AS artist ON (artist.id = albums.artist_id) # LEFT OUTER JOIN genres AS genre ON (genre.id = albums.genre_id) # For each artist, eager_graph load albums and tracks for each album Artist.eager_graph(albums: :tracks).all # SELECT ... # FROM artists # LEFT OUTER JOIN albums ON (albums.artist_id = artists.id) # LEFT OUTER JOIN tracks ON (tracks.album_id = albums.id) # For each artist, eager_graph load albums, tracks for each album, and genre for each track Artist.eager_graph(albums: {tracks: :genre}).all # SELECT ... # FROM artists # LEFT OUTER JOIN albums ON (albums.artist_id = artists.id) # LEFT OUTER JOIN tracks ON (tracks.album_id = albums.id) # LEFT OUTER JOIN genres AS genre ON (genre.id = tracks.genre_id) # For each artist, eager_graph load albums with year > 1990 Artist.eager_graph(albums: proc{|ds| ds.where{year > 1990}}).all # SELECT ... # FROM artists # LEFT OUTER JOIN ( # SELECT * FROM albums WHERE (year > 1990) # ) AS albums ON (albums.artist_id = artists.id) # For each artist, eager_graph load albums and tracks 1-10 for each album Artist.eager_graph(albums: {tracks: proc{|ds| ds.where(number: 1..10)}}).all # SELECT ... # FROM artists # LEFT OUTER JOIN albums ON (albums.artist_id = artists.id) # LEFT OUTER JOIN ( # SELECT * FROM tracks WHERE ((number >= 1) AND (number <= 10)) # ) AS tracks ON (tracks.albums_id = albums.id) # For each artist, eager_graph load albums with year > 1990, and tracks for those albums Artist.eager_graph(albums: {proc{|ds| ds.where{year > 1990}}=>:tracks}).all # SELECT ... # FROM artists # LEFT OUTER JOIN ( # SELECT * FROM albums WHERE (year > 1990) # ) AS albums ON (albums.artist_id = artists.id) # LEFT OUTER JOIN tracks ON (tracks.album_id = albums.id)
# File lib/sequel/model/associations.rb 3057 def eager_graph(*associations) 3058 eager_graph_with_options(associations) 3059 end
Run eager_graph
with some options specific to just this call. Unlike eager_graph
, this takes the associations as a single argument instead of multiple arguments.
Options:
- :join_type
-
Override the join type specified in the association
- :limit_strategy
-
Use a strategy for handling limits on associations. Appropriate :limit_strategy values are:
- true
-
Pick the most appropriate based on what the database supports
- :distinct_on
-
Force use of DISTINCT ON stategy (*_one associations only)
- :correlated_subquery
-
Force use of correlated subquery strategy (one_to_* associations only)
- :window_function
-
Force use of window function strategy
- :ruby
-
Don't modify the
SQL
, implement limits/offsets with array slicing
This can also be a hash with association name symbol keys and one of the above values, to use different strategies per association.
The default is the :ruby strategy. Choosing a different strategy can make your code significantly slower in some cases (perhaps even the majority of cases), so you should only use this if you have benchmarked that it is faster for your use cases.
# File lib/sequel/model/associations.rb 3081 def eager_graph_with_options(associations, opts=OPTS) 3082 return self if associations.empty? 3083 3084 opts = opts.dup unless opts.frozen? 3085 associations = [associations] unless associations.is_a?(Array) 3086 ds = if eg = @opts[:eager_graph] 3087 eg = eg.dup 3088 [:requirements, :reflections, :reciprocals, :limits].each{|k| eg[k] = eg[k].dup} 3089 eg[:local] = opts 3090 ds = clone(:eager_graph=>eg) 3091 ds.eager_graph_associations(ds, model, ds.opts[:eager_graph][:master], [], *associations) 3092 else 3093 # Each of the following have a symbol key for the table alias, with the following values: 3094 # :reciprocals :: the reciprocal value to use for this association 3095 # :reflections :: AssociationReflection instance related to this association 3096 # :requirements :: array of requirements for this association 3097 # :limits :: Any limit/offset array slicing that need to be handled in ruby land after loading 3098 opts = {:requirements=>{}, :master=>alias_symbol(first_source), :reflections=>{}, :reciprocals=>{}, :limits=>{}, :local=>opts, :cartesian_product_number=>0, :row_proc=>row_proc} 3099 ds = clone(:eager_graph=>opts) 3100 ds = ds.eager_graph_associations(ds, model, ds.opts[:eager_graph][:master], [], *associations).naked 3101 end 3102 3103 ds.opts[:eager_graph].freeze 3104 ds.opts[:eager_graph].each_value{|v| v.freeze if v.is_a?(Hash)} 3105 ds 3106 end
If the dataset is being eagerly loaded, default to calling all instead of each.
# File lib/sequel/model/associations.rb 3120 def to_hash_groups(key_column, value_column=nil, opts=OPTS) 3121 if (@opts[:eager_graph] || @opts[:eager]) && !opts.has_key?(:all) 3122 opts = Hash[opts] 3123 opts[:all] = true 3124 end 3125 super 3126 end
Do not attempt to split the result set into associations, just return results as simple objects. This is useful if you want to use eager_graph
as a shortcut to have all of the joins and aliasing set up, but want to do something else with the dataset.
# File lib/sequel/model/associations.rb 3132 def ungraphed 3133 ds = super.clone(:eager_graph=>nil) 3134 if (eg = @opts[:eager_graph]) && (rp = eg[:row_proc]) 3135 ds = ds.with_row_proc(rp) 3136 end 3137 ds 3138 end
Protected Instance Methods
Call graph on the association with the correct arguments, update the eager_graph
data structure, and recurse into eager_graph_associations
if there are any passed in associations (which would be dependencies of the current association)
Arguments:
- ds
-
Current dataset
- model
-
Current
Model
- ta
-
table_alias used for the parent association
- requirements
-
an array, used as a stack for requirements
- r
-
association reflection for the current association, or an
SQL::AliasedExpression
with the reflection as the expression, the alias base as the alias (or nil to use the default alias), and an optional hash with a :join_type entry as the columns to use a custom join type. - *associations
-
any associations dependent on this one
# File lib/sequel/model/associations.rb 3157 def eager_graph_association(ds, model, ta, requirements, r, *associations) 3158 if r.is_a?(SQL::AliasedExpression) 3159 alias_base = r.alias 3160 if r.columns.is_a?(Hash) 3161 join_type = r.columns[:join_type] 3162 end 3163 r = r.expression 3164 else 3165 alias_base = r[:graph_alias_base] 3166 end 3167 assoc_table_alias = ds.unused_table_alias(alias_base) 3168 loader = r[:eager_grapher] 3169 if !associations.empty? 3170 if associations.first.respond_to?(:call) 3171 callback = associations.first 3172 associations = {} 3173 elsif associations.length == 1 && (assocs = associations.first).is_a?(Hash) && assocs.length == 1 && (pr_assoc = assocs.to_a.first) && pr_assoc.first.respond_to?(:call) 3174 callback, assoc = pr_assoc 3175 associations = assoc.is_a?(Array) ? assoc : [assoc] 3176 end 3177 end 3178 local_opts = ds.opts[:eager_graph][:local] 3179 limit_strategy = r.eager_graph_limit_strategy(local_opts[:limit_strategy]) 3180 3181 if r[:conditions] && !Sequel.condition_specifier?(r[:conditions]) && !r[:orig_opts].has_key?(:graph_conditions) && !r[:orig_opts].has_key?(:graph_only_conditions) && !r.has_key?(:graph_block) 3182 raise Error, "Cannot eager_graph association when :conditions specified and not a hash or an array of pairs. Specify :graph_conditions, :graph_only_conditions, or :graph_block for the association. Model: #{r[:model]}, association: #{r[:name]}" 3183 end 3184 3185 ds = loader.call(:self=>ds, :table_alias=>assoc_table_alias, :implicit_qualifier=>(ta == ds.opts[:eager_graph][:master]) ? first_source : qualifier_from_alias_symbol(ta, first_source), :callback=>callback, :join_type=>join_type || local_opts[:join_type], :join_only=>local_opts[:join_only], :limit_strategy=>limit_strategy, :from_self_alias=>ds.opts[:eager_graph][:master]) 3186 if r[:order_eager_graph] && (order = r.fetch(:graph_order, r[:order])) 3187 ds = ds.order_append(*qualified_expression(order, assoc_table_alias)) 3188 end 3189 eager_graph = ds.opts[:eager_graph] 3190 eager_graph[:requirements][assoc_table_alias] = requirements.dup 3191 eager_graph[:reflections][assoc_table_alias] = r 3192 if limit_strategy == :ruby 3193 eager_graph[:limits][assoc_table_alias] = r.limit_and_offset 3194 end 3195 eager_graph[:cartesian_product_number] += r[:cartesian_product_number] || 2 3196 ds = ds.eager_graph_associations(ds, r.associated_class, assoc_table_alias, requirements + [assoc_table_alias], *associations) unless associations.empty? 3197 ds 3198 end
Check the associations are valid for the given model. Call eager_graph_association
on each association.
Arguments:
- ds
-
Current dataset
- model
-
Current
Model
- ta
-
table_alias used for the parent association
- requirements
-
an array, used as a stack for requirements
- *associations
-
the associations to add to the graph
# File lib/sequel/model/associations.rb 3209 def eager_graph_associations(ds, model, ta, requirements, *associations) 3210 associations.flatten.each do |association| 3211 ds = case association 3212 when Symbol, SQL::AliasedExpression 3213 ds.eager_graph_association(ds, model, ta, requirements, eager_graph_check_association(model, association)) 3214 when Hash 3215 association.each do |assoc, assoc_assocs| 3216 ds = ds.eager_graph_association(ds, model, ta, requirements, eager_graph_check_association(model, assoc), assoc_assocs) 3217 end 3218 ds 3219 else 3220 raise(Sequel::Error, 'Associations must be in the form of a symbol or hash') 3221 end 3222 end 3223 ds 3224 end
Replace the array of plain hashes with an array of model objects will all eager_graphed associations set in the associations cache for each object.
# File lib/sequel/model/associations.rb 3228 def eager_graph_build_associations(hashes) 3229 hashes.replace(_eager_graph_build_associations(hashes, eager_graph_loader)) 3230 end
Private Instance Methods
Return a new dataset with JOINs of the given type added, using the tables and conditions specified by the associations.
# File lib/sequel/model/associations.rb 3236 def _association_join(type, associations) 3237 clone(:join=>clone(:graph_from_self=>false).eager_graph_with_options(associations, :join_type=>type, :join_only=>true).opts[:join]) 3238 end
Process the array of hashes using the eager graph loader to return an array of model objects with the associations set.
# File lib/sequel/model/associations.rb 3242 def _eager_graph_build_associations(hashes, egl) 3243 egl.load(hashes) 3244 end
If the association has conditions itself, then it requires additional filters be added to the current dataset to ensure that the passed in object would also be included by the association's conditions.
# File lib/sequel/model/associations.rb 3249 def add_association_filter_conditions(ref, obj, expr) 3250 if expr != SQL::Constants::FALSE && ref.filter_by_associations_add_conditions? 3251 Sequel[ref.filter_by_associations_conditions_expression(obj)] 3252 else 3253 expr 3254 end 3255 end
Return an expression for filtering by the given association reflection and associated object.
# File lib/sequel/model/associations.rb 3277 def association_filter_expression(op, ref, obj) 3278 meth = :"#{ref[:type]}_association_filter_expression" 3279 # Allow calling private association specific method to get filter expression 3280 send(meth, op, ref, obj) if respond_to?(meth, true) 3281 end
Handle inversion for association filters by returning an inverted expression, plus also handling cases where the referenced columns are NULL.
# File lib/sequel/model/associations.rb 3285 def association_filter_handle_inversion(op, exp, cols) 3286 if op == :'!=' || op == :'NOT IN' 3287 if exp == SQL::Constants::FALSE 3288 ~exp 3289 else 3290 ~exp | Sequel::SQL::BooleanExpression.from_value_pairs(cols.zip([]), :OR) 3291 end 3292 else 3293 exp 3294 end 3295 end
Return an expression for making sure that the given keys match the value of the given methods for either the single object given or for any of the objects given if obj
is an array.
# File lib/sequel/model/associations.rb 3300 def association_filter_key_expression(keys, meths, obj) 3301 vals = if obj.is_a?(Sequel::Dataset) 3302 {(keys.length == 1 ? keys.first : keys)=>obj.select(*meths).exclude(Sequel::SQL::BooleanExpression.from_value_pairs(meths.zip([]), :OR))} 3303 else 3304 vals = Array(obj).reject{|o| !meths.all?{|m| o.get_column_value(m)}} 3305 return SQL::Constants::FALSE if vals.empty? 3306 if obj.is_a?(Array) 3307 if keys.length == 1 3308 meth = meths.first 3309 {keys.first=>vals.map{|o| o.get_column_value(meth)}} 3310 else 3311 {keys=>vals.map{|o| meths.map{|m| o.get_column_value(m)}}} 3312 end 3313 else 3314 keys.zip(meths.map{|k| obj.get_column_value(k)}) 3315 end 3316 end 3317 SQL::BooleanExpression.from_value_pairs(vals) 3318 end
Make sure the association is valid for this model, and return the related AssociationReflection
.
# File lib/sequel/model/associations.rb 3321 def check_association(model, association) 3322 raise(Sequel::UndefinedAssociation, "Invalid association #{association} for #{model.name}") unless reflection = model.association_reflection(association) 3323 raise(Sequel::Error, "Eager loading is not allowed for #{model.name} association #{association}") if reflection[:allow_eager] == false 3324 reflection 3325 end
Allow associations that are eagerly graphed to be specified as an SQL::AliasedExpression
, for per-call determining of the alias base.
# File lib/sequel/model/associations.rb 3329 def eager_graph_check_association(model, association) 3330 if association.is_a?(SQL::AliasedExpression) 3331 expr = association.expression 3332 if expr.is_a?(SQL::Identifier) 3333 expr = expr.value 3334 if expr.is_a?(String) 3335 expr = expr.to_sym 3336 end 3337 end 3338 3339 SQL::AliasedExpression.new(check_association(model, expr), association.alias || expr, association.columns) 3340 else 3341 check_association(model, association) 3342 end 3343 end
The EagerGraphLoader
instance used for converting eager_graph
results.
# File lib/sequel/model/associations.rb 3346 def eager_graph_loader 3347 unless egl = cache_get(:_model_eager_graph_loader) 3348 egl = cache_set(:_model_eager_graph_loader, EagerGraphLoader.new(self)) 3349 end 3350 egl.dup 3351 end
Eagerly load all specified associations
# File lib/sequel/model/associations.rb 3354 def eager_load(a, eager_assoc=@opts[:eager]) 3355 return if a.empty? 3356 # Key is foreign/primary key name symbol. 3357 # Value is hash with keys being foreign/primary key values (generally integers) 3358 # and values being an array of current model objects with that specific foreign/primary key 3359 key_hash = {} 3360 # Reflections for all associations to eager load 3361 reflections = eager_assoc.keys.map{|assoc| model.association_reflection(assoc) || (raise Sequel::UndefinedAssociation, "Model: #{self}, Association: #{assoc}")} 3362 3363 # Populate the key_hash entry for each association being eagerly loaded 3364 reflections.each do |r| 3365 if key = r.eager_loader_key 3366 # key_hash for this key has already been populated, 3367 # skip populating again so that duplicate values 3368 # aren't added. 3369 unless id_map = key_hash[key] 3370 id_map = key_hash[key] = Hash.new{|h,k| h[k] = []} 3371 3372 # Supporting both single (Symbol) and composite (Array) keys. 3373 a.each do |rec| 3374 case key 3375 when Array 3376 if (k = key.map{|k2| rec.get_column_value(k2)}) && k.all? 3377 id_map[k] << rec 3378 end 3379 when Symbol 3380 if k = rec.get_column_value(key) 3381 id_map[k] << rec 3382 end 3383 else 3384 raise Error, "unhandled eager_loader_key #{key.inspect} for association #{r[:name]}" 3385 end 3386 end 3387 end 3388 else 3389 id_map = nil 3390 end 3391 3392 loader = r[:eager_loader] 3393 associations = eager_assoc[r[:name]] 3394 if associations.respond_to?(:call) 3395 eager_block = associations 3396 associations = OPTS 3397 elsif associations.is_a?(Hash) && associations.length == 1 && (pr_assoc = associations.to_a.first) && pr_assoc.first.respond_to?(:call) 3398 eager_block, associations = pr_assoc 3399 end 3400 loader.call(:key_hash=>key_hash, :rows=>a, :associations=>associations, :self=>self, :eager_block=>eager_block, :id_map=>id_map) 3401 a.each{|object| object.send(:run_association_callbacks, r, :after_load, object.associations[r[:name]])} if r[:after_load] 3402 end 3403 end
Process the array of associations arguments (Symbols, Arrays, and Hashes), and return a hash of options suitable for cascading.
# File lib/sequel/model/associations.rb 3259 def eager_options_for_associations(associations) 3260 opts = {} 3261 associations.flatten.each do |association| 3262 case association 3263 when Symbol 3264 check_association(model, association) 3265 opts[association] = nil 3266 when Hash 3267 association.keys.each{|assoc| check_association(model, assoc)} 3268 opts.merge!(association) 3269 else 3270 raise(Sequel::Error, 'Associations must be in the form of a symbol or hash') 3271 end 3272 end 3273 opts 3274 end
Return a subquery expression for filering by a many_to_many association
# File lib/sequel/model/associations.rb 3406 def many_to_many_association_filter_expression(op, ref, obj) 3407 lpks, lks, rks = ref.values_at(:left_primary_key_columns, :left_keys, :right_keys) 3408 jt = ref.join_table_alias 3409 lpks = lpks.first if lpks.length == 1 3410 lpks = ref.qualify(model.table_name, lpks) 3411 3412 meths = if obj.is_a?(Sequel::Dataset) 3413 ref.qualify(obj.model.table_name, ref.right_primary_keys) 3414 else 3415 ref.right_primary_key_methods 3416 end 3417 3418 expr = association_filter_key_expression(ref.qualify(jt, rks), meths, obj) 3419 unless expr == SQL::Constants::FALSE 3420 expr = SQL::BooleanExpression.from_value_pairs(lpks=>model.db.from(ref[:join_table]).select(*ref.qualify(jt, lks)).where(expr).exclude(SQL::BooleanExpression.from_value_pairs(ref.qualify(jt, lks).zip([]), :OR))) 3421 expr = add_association_filter_conditions(ref, obj, expr) 3422 end 3423 3424 association_filter_handle_inversion(op, expr, Array(lpks)) 3425 end
Return a simple equality expression for filering by a many_to_one association
# File lib/sequel/model/associations.rb 3429 def many_to_one_association_filter_expression(op, ref, obj) 3430 keys = ref.qualify(model.table_name, ref[:key_columns]) 3431 meths = if obj.is_a?(Sequel::Dataset) 3432 ref.qualify(obj.model.table_name, ref.primary_keys) 3433 else 3434 ref.primary_key_methods 3435 end 3436 3437 expr = association_filter_key_expression(keys, meths, obj) 3438 expr = add_association_filter_conditions(ref, obj, expr) 3439 association_filter_handle_inversion(op, expr, keys) 3440 end
# File lib/sequel/model/associations.rb 3457 def non_sql_option?(key) 3458 super || key == :eager || key == :eager_graph 3459 end
Return a simple equality expression for filering by a one_to_* association
# File lib/sequel/model/associations.rb 3443 def one_to_many_association_filter_expression(op, ref, obj) 3444 keys = ref.qualify(model.table_name, ref[:primary_key_columns]) 3445 meths = if obj.is_a?(Sequel::Dataset) 3446 ref.qualify(obj.model.table_name, ref[:keys]) 3447 else 3448 ref[:key_methods] 3449 end 3450 3451 expr = association_filter_key_expression(keys, meths, obj) 3452 expr = add_association_filter_conditions(ref, obj, expr) 3453 association_filter_handle_inversion(op, expr, keys) 3454 end
Build associations from the graph if eager_graph
was used, and/or load other associations if eager
was used.
# File lib/sequel/model/associations.rb 3463 def post_load(all_records) 3464 eager_graph_build_associations(all_records) if @opts[:eager_graph] 3465 eager_load(all_records) if @opts[:eager] && (row_proc || @opts[:eager_graph]) 3466 super 3467 end