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

as_hash(key_column=nil, value_column=nil, opts=OPTS) click to toggle source

If the dataset is being eagerly loaded, default to calling all instead of each.

Calls superclass method
     # File lib/sequel/model/associations.rb
3336 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
3337   if (@opts[:eager_graph] || @opts[:eager]) && !opts.has_key?(:all)
3338     opts = Hash[opts]
3339     opts[:all] = true
3340   end
3341   super
3342 end
association_join(*associations) click to toggle source

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
3042 def association_join(*associations)
3043   association_inner_join(*associations)
3044 end
complex_expression_sql_append(sql, op, args) click to toggle source

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.

Calls superclass method
     # File lib/sequel/model/associations.rb
3053 def complex_expression_sql_append(sql, op, args)
3054   r = args[1]
3055   if (((op == :'=' || op == :'!=') && r.is_a?(Sequel::Model)) ||
3056       (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)})))))
3057     l = args[0]
3058     if ar = model.association_reflections[l]
3059       raise Error, "filtering by associations is not allowed for #{ar.inspect}" if ar[:allow_filtering_by] == false
3060 
3061       if multiple
3062         klass = ar.associated_class
3063         if is_ds
3064           if r.respond_to?(:model)
3065             unless r.model <= klass
3066               # A dataset for a different model class, could be a valid regular query
3067               return super
3068             end
3069           else
3070             # Not a model dataset, could be a valid regular query
3071             return super
3072           end
3073         else
3074           unless r.all?{|x| x.is_a?(klass)}
3075             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}"
3076           end
3077         end
3078       elsif !r.is_a?(ar.associated_class)
3079         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}"
3080       end
3081 
3082       if exp = association_filter_expression(op, ar, r)
3083         literal_append(sql, exp)
3084       else
3085         raise Sequel::Error, "invalid association type #{ar[:type].inspect} for association #{l.inspect} used in dataset filter for model #{model.inspect}"
3086       end
3087     elsif multiple && (is_ds || r.empty?)
3088       # Not a query designed for this support, could be a valid regular query
3089       super
3090     else
3091       raise Sequel::Error, "invalid association #{l.inspect} used in dataset filter for model #{model.inspect}"
3092     end
3093   else
3094     super
3095   end
3096 end
eager(*associations) click to toggle source

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
3173 def eager(*associations)
3174   opts = @opts[:eager]
3175   association_opts = eager_options_for_associations(associations)
3176   opts = opts ? opts.merge(association_opts) : association_opts
3177   clone(:eager=>opts.freeze)
3178 end
eager_graph(*associations) click to toggle source

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 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.

You cannot mix calls to eager_graph and graph on the same dataset.

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
3283 def eager_graph(*associations)
3284   eager_graph_with_options(associations)
3285 end
eager_graph_with_options(associations, opts=OPTS) click to toggle source

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
3307 def eager_graph_with_options(associations, opts=OPTS)
3308   return self if associations.empty?
3309 
3310   opts = opts.dup unless opts.frozen?
3311   associations = [associations] unless associations.is_a?(Array)
3312   ds = if eg = @opts[:eager_graph]
3313     eg = eg.dup
3314     [:requirements, :reflections, :reciprocals, :limits].each{|k| eg[k] = eg[k].dup}
3315     eg[:local] = opts
3316     ds = clone(:eager_graph=>eg)
3317     ds.eager_graph_associations(ds, model, ds.opts[:eager_graph][:master], [], *associations)
3318   else
3319     # Each of the following have a symbol key for the table alias, with the following values:
3320     # :reciprocals :: the reciprocal value to use for this association
3321     # :reflections :: AssociationReflection instance related to this association
3322     # :requirements :: array of requirements for this association
3323     # :limits :: Any limit/offset array slicing that need to be handled in ruby land after loading
3324     opts = {:requirements=>{}, :master=>alias_symbol(first_source), :reflections=>{}, :reciprocals=>{}, :limits=>{}, :local=>opts, :cartesian_product_number=>0, :row_proc=>row_proc}
3325     ds = clone(:eager_graph=>opts)
3326     ds = ds.eager_graph_associations(ds, model, ds.opts[:eager_graph][:master], [], *associations).naked
3327   end
3328 
3329   ds.opts[:eager_graph].freeze
3330   ds.opts[:eager_graph].each_value{|v| v.freeze if v.is_a?(Hash)}
3331   ds
3332 end
to_hash_groups(key_column, value_column=nil, opts=OPTS) click to toggle source

If the dataset is being eagerly loaded, default to calling all instead of each.

Calls superclass method
     # File lib/sequel/model/associations.rb
3346 def to_hash_groups(key_column, value_column=nil, opts=OPTS)
3347   if (@opts[:eager_graph] || @opts[:eager]) && !opts.has_key?(:all)
3348     opts = Hash[opts]
3349     opts[:all] = true
3350   end
3351   super
3352 end
ungraphed() click to toggle source

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.

Calls superclass method
     # File lib/sequel/model/associations.rb
3358 def ungraphed
3359   ds = super.clone(:eager_graph=>nil)
3360   if (eg = @opts[:eager_graph]) && (rp = eg[:row_proc])
3361     ds = ds.with_row_proc(rp)
3362   end
3363   ds
3364 end

Protected Instance Methods

eager_graph_association(ds, model, ta, requirements, r, *associations) click to toggle source

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
3383 def eager_graph_association(ds, model, ta, requirements, r, *associations)
3384   if r.is_a?(SQL::AliasedExpression)
3385     alias_base = r.alias
3386     if r.columns.is_a?(Hash)
3387       join_type = r.columns[:join_type]
3388     end
3389     r = r.expression
3390   else
3391     alias_base = r[:graph_alias_base]
3392   end
3393   assoc_table_alias = ds.unused_table_alias(alias_base)
3394   loader = r[:eager_grapher]
3395   if !associations.empty?
3396     if associations.first.respond_to?(:call)
3397       callback = associations.first
3398       associations = {}
3399     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)
3400       callback, assoc = pr_assoc
3401       associations = assoc.is_a?(Array) ? assoc : [assoc]
3402     end
3403   end
3404   local_opts = ds.opts[:eager_graph][:local]
3405   limit_strategy = r.eager_graph_limit_strategy(local_opts[:limit_strategy])
3406 
3407   # SEQUEL6: remove and integrate the auto_restrict_eager_graph plugin
3408   if !r[:orig_opts].has_key?(:graph_conditions) && !r[:orig_opts].has_key?(:graph_only_conditions) && !r.has_key?(:graph_block) && !r[:allow_eager_graph]
3409     if r[:conditions] && !Sequel.condition_specifier?(r[:conditions])
3410       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]}"
3411     end
3412 
3413     if r[:block] && !r[:graph_use_association_block]
3414       warn "eager_graph used for association when association given a block without graph options.  The block is ignored in this case.  This will result in an exception starting in Sequel 6.  Model: #{r[:model]}, association: #{r[:name]}"
3415     end
3416   end
3417 
3418   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])
3419   if r[:order_eager_graph] && (order = r.fetch(:graph_order, r[:order]))
3420     ds = ds.order_append(*qualified_expression(order, assoc_table_alias))
3421   end
3422   eager_graph = ds.opts[:eager_graph]
3423   eager_graph[:requirements][assoc_table_alias] = requirements.dup
3424   eager_graph[:reflections][assoc_table_alias] = r
3425   if limit_strategy == :ruby
3426     eager_graph[:limits][assoc_table_alias] = r.limit_and_offset 
3427   end
3428   eager_graph[:cartesian_product_number] += r[:cartesian_product_number] || 2
3429   ds = ds.eager_graph_associations(ds, r.associated_class, assoc_table_alias, requirements + [assoc_table_alias], *associations) unless associations.empty?
3430   ds
3431 end
eager_graph_associations(ds, model, ta, requirements, *associations) click to toggle source

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
3442 def eager_graph_associations(ds, model, ta, requirements, *associations)
3443   associations.flatten.each do |association|
3444     ds = case association
3445     when Symbol, SQL::AliasedExpression
3446       ds.eager_graph_association(ds, model, ta, requirements, eager_graph_check_association(model, association))
3447     when Hash
3448       association.each do |assoc, assoc_assocs|
3449         ds = ds.eager_graph_association(ds, model, ta, requirements, eager_graph_check_association(model, assoc), assoc_assocs)
3450       end
3451       ds
3452     else
3453       raise(Sequel::Error, 'Associations must be in the form of a symbol or hash')
3454     end
3455   end
3456   ds
3457 end
eager_graph_build_associations(hashes) click to toggle source

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
3461 def eager_graph_build_associations(hashes)
3462   hashes.replace(_eager_graph_build_associations(hashes, eager_graph_loader))
3463 end

Private Instance Methods

_association_join(type, associations) click to toggle source

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
3469 def _association_join(type, associations)
3470   clone(:join=>clone(:graph_from_self=>false).eager_graph_with_options(associations, :join_type=>type, :join_only=>true).opts[:join])
3471 end
_eager_graph_build_associations(hashes, egl) click to toggle source

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
3475 def _eager_graph_build_associations(hashes, egl)
3476   egl.load(hashes)
3477 end
add_association_filter_conditions(ref, obj, expr) click to toggle source

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
3482 def add_association_filter_conditions(ref, obj, expr)
3483   if expr != SQL::Constants::FALSE && ref.filter_by_associations_add_conditions?
3484     Sequel[ref.filter_by_associations_conditions_expression(obj)]
3485   else
3486     expr
3487   end
3488 end
association_filter_expression(op, ref, obj) click to toggle source

Return an expression for filtering by the given association reflection and associated object.

     # File lib/sequel/model/associations.rb
3510 def association_filter_expression(op, ref, obj)
3511   meth = :"#{ref[:type]}_association_filter_expression"
3512   # Allow calling private association specific method to get filter expression
3513   send(meth, op, ref, obj) if respond_to?(meth, true)
3514 end
association_filter_handle_inversion(op, exp, cols) click to toggle source

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
3518 def association_filter_handle_inversion(op, exp, cols)
3519   if op == :'!=' || op == :'NOT IN'
3520     if exp == SQL::Constants::FALSE
3521       ~exp
3522     else
3523       ~exp | Sequel::SQL::BooleanExpression.from_value_pairs(cols.zip([]), :OR)
3524     end
3525   else
3526     exp
3527   end
3528 end
association_filter_key_expression(keys, meths, obj) click to toggle source

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
3533 def association_filter_key_expression(keys, meths, obj)
3534   vals = if obj.is_a?(Sequel::Dataset)
3535     {(keys.length == 1 ? keys.first : keys)=>obj.select(*meths).exclude(Sequel::SQL::BooleanExpression.from_value_pairs(meths.zip([]), :OR))}
3536   else
3537     vals = Array(obj).reject{|o| !meths.all?{|m| o.get_column_value(m)}}
3538     return SQL::Constants::FALSE if vals.empty?
3539     if obj.is_a?(Array)
3540       if keys.length == 1
3541         meth = meths.first
3542         {keys.first=>vals.map{|o| o.get_column_value(meth)}}
3543       else
3544         {keys=>vals.map{|o| meths.map{|m| o.get_column_value(m)}}}
3545       end  
3546     else
3547       keys.zip(meths.map{|k| obj.get_column_value(k)})
3548     end
3549   end
3550   SQL::BooleanExpression.from_value_pairs(vals)
3551 end
check_association(model, association) click to toggle source

Make sure the association is valid for this model, and return the related AssociationReflection.

     # File lib/sequel/model/associations.rb
3554 def check_association(model, association)
3555   raise(Sequel::UndefinedAssociation, "Invalid association #{association} for #{model.name}") unless reflection = model.association_reflection(association)
3556   raise(Sequel::Error, "Eager loading is not allowed for #{model.name} association #{association}") if reflection[:allow_eager] == false
3557   reflection
3558 end
eager_graph_check_association(model, association) click to toggle source

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
3562 def eager_graph_check_association(model, association)
3563   reflection = if association.is_a?(SQL::AliasedExpression)
3564     expr = association.expression
3565     if expr.is_a?(SQL::Identifier)
3566       expr = expr.value
3567       if expr.is_a?(String)
3568         expr = expr.to_sym
3569       end
3570     end
3571 
3572     check_reflection = check_association(model, expr)
3573     SQL::AliasedExpression.new(check_reflection, association.alias || expr, association.columns)
3574   else
3575     check_reflection = check_association(model, association)
3576   end
3577 
3578   if check_reflection && check_reflection[:allow_eager_graph] == false
3579     raise Error, "eager_graph not allowed for #{reflection.inspect}"
3580   end
3581 
3582   reflection
3583 end
eager_graph_loader() click to toggle source

The EagerGraphLoader instance used for converting eager_graph results.

     # File lib/sequel/model/associations.rb
3586 def eager_graph_loader
3587   unless egl = cache_get(:_model_eager_graph_loader)
3588     egl = cache_set(:_model_eager_graph_loader, EagerGraphLoader.new(self))
3589   end
3590   egl.dup
3591 end
eager_load(a, eager_assoc=@opts[:eager], m=model) click to toggle source

Eagerly load all specified associations.

     # File lib/sequel/model/associations.rb
3594 def eager_load(a, eager_assoc=@opts[:eager], m=model)
3595   return if a.empty?
3596 
3597   # Reflections for all associations to eager load
3598   reflections = eager_assoc.keys.map{|assoc| m.association_reflection(assoc) || (raise Sequel::UndefinedAssociation, "Model: #{self}, Association: #{assoc}")}
3599 
3600   perform_eager_loads(prepare_eager_load(a, reflections, eager_assoc))
3601 
3602   reflections.each do |r|
3603     a.each{|object| object.send(:run_association_callbacks, r, :after_load, object.associations[r[:name]])} if r[:after_load]
3604   end 
3605 
3606   nil
3607 end
eager_options_for_associations(associations) click to toggle source

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
3492 def eager_options_for_associations(associations)
3493   opts = {}
3494   associations.flatten.each do |association|
3495     case association
3496     when Symbol
3497       check_association(model, association)
3498       opts[association] = nil
3499     when Hash
3500       association.keys.each{|assoc| check_association(model, assoc)}
3501       opts.merge!(association)
3502     else
3503       raise(Sequel::Error, 'Associations must be in the form of a symbol or hash')
3504     end
3505   end
3506   opts
3507 end
many_to_many_association_filter_expression(op, ref, obj) click to toggle source

Return a subquery expression for filering by a many_to_many association

     # File lib/sequel/model/associations.rb
3674 def many_to_many_association_filter_expression(op, ref, obj)
3675   lpks, lks, rks = ref.values_at(:left_primary_key_columns, :left_keys, :right_keys)
3676   jt = ref.join_table_alias
3677   lpks = lpks.first if lpks.length == 1
3678   lpks = ref.qualify(model.table_name, lpks)
3679 
3680   meths = if obj.is_a?(Sequel::Dataset)
3681     ref.qualify(obj.model.table_name, ref.right_primary_keys)
3682   else
3683     ref.right_primary_key_methods
3684   end
3685 
3686   expr = association_filter_key_expression(ref.qualify(jt, rks), meths, obj)
3687   unless expr == SQL::Constants::FALSE
3688     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)))
3689     expr = add_association_filter_conditions(ref, obj, expr)
3690   end
3691 
3692   association_filter_handle_inversion(op, expr, Array(lpks))
3693 end
many_to_one_association_filter_expression(op, ref, obj) click to toggle source

Return a simple equality expression for filering by a many_to_one association

     # File lib/sequel/model/associations.rb
3697 def many_to_one_association_filter_expression(op, ref, obj)
3698   keys = ref.qualify(model.table_name, ref[:key_columns])
3699   meths = if obj.is_a?(Sequel::Dataset)
3700     ref.qualify(obj.model.table_name, ref.primary_keys)
3701   else
3702     ref.primary_key_methods
3703   end
3704 
3705   expr = association_filter_key_expression(keys, meths, obj)
3706   expr = add_association_filter_conditions(ref, obj, expr)
3707   association_filter_handle_inversion(op, expr, keys)
3708 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/associations.rb
3725 def non_sql_option?(key)
3726   super || key == :eager || key == :eager_graph
3727 end
one_through_one_association_filter_expression(op, ref, obj)
one_to_many_association_filter_expression(op, ref, obj) click to toggle source

Return a simple equality expression for filering by a one_to_* association

     # File lib/sequel/model/associations.rb
3711 def one_to_many_association_filter_expression(op, ref, obj)
3712   keys = ref.qualify(model.table_name, ref[:primary_key_columns])
3713   meths = if obj.is_a?(Sequel::Dataset)
3714     ref.qualify(obj.model.table_name, ref[:keys])
3715   else
3716     ref[:key_methods]
3717   end
3718 
3719   expr = association_filter_key_expression(keys, meths, obj)
3720   expr = add_association_filter_conditions(ref, obj, expr)
3721   association_filter_handle_inversion(op, expr, keys)
3722 end
one_to_one_association_filter_expression(op, ref, obj)
perform_eager_load(loader, eo) click to toggle source

Perform eager loading for a single association using the loader and eager options.

     # File lib/sequel/model/associations.rb
3669 def perform_eager_load(loader, eo)
3670   loader.call(eo)
3671 end
perform_eager_loads(eager_load_data) click to toggle source

Using the hash of loaders and eager options, perform the eager loading.

     # File lib/sequel/model/associations.rb
3662 def perform_eager_loads(eager_load_data)
3663   eager_load_data.map do |loader, eo|
3664     perform_eager_load(loader, eo)
3665   end
3666 end
post_load(all_records) click to toggle source

Build associations from the graph if eager_graph was used, and/or load other associations if eager was used.

Calls superclass method
     # File lib/sequel/model/associations.rb
3731 def post_load(all_records)
3732   eager_graph_build_associations(all_records) if @opts[:eager_graph]
3733   eager_load(all_records) if @opts[:eager] && (row_proc || @opts[:eager_graph])
3734   super
3735 end
prepare_eager_load(a, reflections, eager_assoc) click to toggle source

Prepare a hash loaders and eager options which will be used to implement the eager loading.

     # File lib/sequel/model/associations.rb
3610 def prepare_eager_load(a, reflections, eager_assoc)
3611   eager_load_data = {}
3612 
3613   # Key is foreign/primary key name symbol.
3614   # Value is hash with keys being foreign/primary key values (generally integers)
3615   # and values being an array of current model objects with that specific foreign/primary key
3616   key_hash = {}
3617       
3618   # Populate the key_hash entry for each association being eagerly loaded
3619   reflections.each do |r|
3620     if key = r.eager_loader_key
3621       # key_hash for this key has already been populated,
3622       # skip populating again so that duplicate values
3623       # aren't added.
3624       unless id_map = key_hash[key]
3625         id_map = key_hash[key] = Hash.new{|h,k| h[k] = []}
3626 
3627         # Supporting both single (Symbol) and composite (Array) keys.
3628         a.each do |rec|
3629           case key
3630           when Array
3631             if (k = key.map{|k2| rec.get_column_value(k2)}) && k.all?
3632               id_map[k] << rec
3633             end
3634           when Symbol
3635             if k = rec.get_column_value(key)
3636               id_map[k] << rec
3637             end
3638           else
3639             raise Error, "unhandled eager_loader_key #{key.inspect} for association #{r[:name]}"
3640           end
3641         end
3642       end
3643     else
3644       id_map = nil
3645     end
3646   
3647     associations = eager_assoc[r[:name]]
3648     if associations.respond_to?(:call)
3649       eager_block = associations
3650       associations = OPTS
3651     elsif associations.is_a?(Hash) && associations.length == 1 && (pr_assoc = associations.to_a.first) && pr_assoc.first.respond_to?(:call)
3652       eager_block, associations = pr_assoc
3653     end
3654 
3655     eager_load_data[r[:eager_loader]] = {:key_hash=>key_hash, :rows=>a, :associations=>associations, :self=>self, :eager_block=>eager_block, :id_map=>id_map}
3656   end
3657 
3658   eager_load_data
3659 end