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
3111 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
3112   if (@opts[:eager_graph] || @opts[:eager]) && !opts.has_key?(:all)
3113     opts = Hash[opts]
3114     opts[:all] = true
3115   end
3116   super
3117 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
2821 def association_join(*associations)
2822   association_inner_join(*associations)
2823 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
2832 def complex_expression_sql_append(sql, op, args)
2833   r = args[1]
2834   if (((op == :'=' || op == :'!=') && r.is_a?(Sequel::Model)) ||
2835       (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)})))))
2836     l = args[0]
2837     if ar = model.association_reflections[l]
2838       if multiple
2839         klass = ar.associated_class
2840         if is_ds
2841           if r.respond_to?(:model)
2842             unless r.model <= klass
2843               # A dataset for a different model class, could be a valid regular query
2844               return super
2845             end
2846           else
2847             # Not a model dataset, could be a valid regular query
2848             return super
2849           end
2850         else
2851           unless r.all?{|x| x.is_a?(klass)}
2852             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}"
2853           end
2854         end
2855       elsif !r.is_a?(ar.associated_class)
2856         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}"
2857       end
2858 
2859       if exp = association_filter_expression(op, ar, r)
2860         literal_append(sql, exp)
2861       else
2862         raise Sequel::Error, "invalid association type #{ar[:type].inspect} for association #{l.inspect} used in dataset filter for model #{model.inspect}"
2863       end
2864     elsif multiple && (is_ds || r.empty?)
2865       # Not a query designed for this support, could be a valid regular query
2866       super
2867     else
2868       raise Sequel::Error, "invalid association #{l.inspect} used in dataset filter for model #{model.inspect}"
2869     end
2870   else
2871     super
2872   end
2873 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
2950 def eager(*associations)
2951   opts = @opts[:eager]
2952   association_opts = eager_options_for_associations(associations)
2953   opts = opts ? opts.merge(association_opts) : association_opts
2954   clone(:eager=>opts.freeze)
2955 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 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
3058 def eager_graph(*associations)
3059   eager_graph_with_options(associations)
3060 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
3082 def eager_graph_with_options(associations, opts=OPTS)
3083   return self if associations.empty?
3084 
3085   opts = opts.dup unless opts.frozen?
3086   associations = [associations] unless associations.is_a?(Array)
3087   ds = if eg = @opts[:eager_graph]
3088     eg = eg.dup
3089     [:requirements, :reflections, :reciprocals, :limits].each{|k| eg[k] = eg[k].dup}
3090     eg[:local] = opts
3091     ds = clone(:eager_graph=>eg)
3092     ds.eager_graph_associations(ds, model, ds.opts[:eager_graph][:master], [], *associations)
3093   else
3094     # Each of the following have a symbol key for the table alias, with the following values:
3095     # :reciprocals :: the reciprocal value to use for this association
3096     # :reflections :: AssociationReflection instance related to this association
3097     # :requirements :: array of requirements for this association
3098     # :limits :: Any limit/offset array slicing that need to be handled in ruby land after loading
3099     opts = {:requirements=>{}, :master=>alias_symbol(first_source), :reflections=>{}, :reciprocals=>{}, :limits=>{}, :local=>opts, :cartesian_product_number=>0, :row_proc=>row_proc}
3100     ds = clone(:eager_graph=>opts)
3101     ds = ds.eager_graph_associations(ds, model, ds.opts[:eager_graph][:master], [], *associations).naked
3102   end
3103 
3104   ds.opts[:eager_graph].freeze
3105   ds.opts[:eager_graph].each_value{|v| v.freeze if v.is_a?(Hash)}
3106   ds
3107 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
3121 def to_hash_groups(key_column, value_column=nil, opts=OPTS)
3122   if (@opts[:eager_graph] || @opts[:eager]) && !opts.has_key?(:all)
3123     opts = Hash[opts]
3124     opts[:all] = true
3125   end
3126   super
3127 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
3133 def ungraphed
3134   ds = super.clone(:eager_graph=>nil)
3135   if (eg = @opts[:eager_graph]) && (rp = eg[:row_proc])
3136     ds = ds.with_row_proc(rp)
3137   end
3138   ds
3139 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
3158 def eager_graph_association(ds, model, ta, requirements, r, *associations)
3159   if r.is_a?(SQL::AliasedExpression)
3160     alias_base = r.alias
3161     if r.columns.is_a?(Hash)
3162       join_type = r.columns[:join_type]
3163     end
3164     r = r.expression
3165   else
3166     alias_base = r[:graph_alias_base]
3167   end
3168   assoc_table_alias = ds.unused_table_alias(alias_base)
3169   loader = r[:eager_grapher]
3170   if !associations.empty?
3171     if associations.first.respond_to?(:call)
3172       callback = associations.first
3173       associations = {}
3174     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)
3175       callback, assoc = pr_assoc
3176       associations = assoc.is_a?(Array) ? assoc : [assoc]
3177     end
3178   end
3179   local_opts = ds.opts[:eager_graph][:local]
3180   limit_strategy = r.eager_graph_limit_strategy(local_opts[:limit_strategy])
3181 
3182   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)
3183     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]}"
3184   end
3185 
3186   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])
3187   if r[:order_eager_graph] && (order = r.fetch(:graph_order, r[:order]))
3188     ds = ds.order_append(*qualified_expression(order, assoc_table_alias))
3189   end
3190   eager_graph = ds.opts[:eager_graph]
3191   eager_graph[:requirements][assoc_table_alias] = requirements.dup
3192   eager_graph[:reflections][assoc_table_alias] = r
3193   if limit_strategy == :ruby
3194     eager_graph[:limits][assoc_table_alias] = r.limit_and_offset 
3195   end
3196   eager_graph[:cartesian_product_number] += r[:cartesian_product_number] || 2
3197   ds = ds.eager_graph_associations(ds, r.associated_class, assoc_table_alias, requirements + [assoc_table_alias], *associations) unless associations.empty?
3198   ds
3199 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
3210 def eager_graph_associations(ds, model, ta, requirements, *associations)
3211   associations.flatten.each do |association|
3212     ds = case association
3213     when Symbol, SQL::AliasedExpression
3214       ds.eager_graph_association(ds, model, ta, requirements, eager_graph_check_association(model, association))
3215     when Hash
3216       association.each do |assoc, assoc_assocs|
3217         ds = ds.eager_graph_association(ds, model, ta, requirements, eager_graph_check_association(model, assoc), assoc_assocs)
3218       end
3219       ds
3220     else
3221       raise(Sequel::Error, 'Associations must be in the form of a symbol or hash')
3222     end
3223   end
3224   ds
3225 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
3229 def eager_graph_build_associations(hashes)
3230   hashes.replace(_eager_graph_build_associations(hashes, eager_graph_loader))
3231 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
3237 def _association_join(type, associations)
3238   clone(:join=>clone(:graph_from_self=>false).eager_graph_with_options(associations, :join_type=>type, :join_only=>true).opts[:join])
3239 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
3243 def _eager_graph_build_associations(hashes, egl)
3244   egl.load(hashes)
3245 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
3250 def add_association_filter_conditions(ref, obj, expr)
3251   if expr != SQL::Constants::FALSE && ref.filter_by_associations_add_conditions?
3252     Sequel[ref.filter_by_associations_conditions_expression(obj)]
3253   else
3254     expr
3255   end
3256 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
3278 def association_filter_expression(op, ref, obj)
3279   meth = :"#{ref[:type]}_association_filter_expression"
3280   # Allow calling private association specific method to get filter expression
3281   send(meth, op, ref, obj) if respond_to?(meth, true)
3282 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
3286 def association_filter_handle_inversion(op, exp, cols)
3287   if op == :'!=' || op == :'NOT IN'
3288     if exp == SQL::Constants::FALSE
3289       ~exp
3290     else
3291       ~exp | Sequel::SQL::BooleanExpression.from_value_pairs(cols.zip([]), :OR)
3292     end
3293   else
3294     exp
3295   end
3296 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
3301 def association_filter_key_expression(keys, meths, obj)
3302   vals = if obj.is_a?(Sequel::Dataset)
3303     {(keys.length == 1 ? keys.first : keys)=>obj.select(*meths).exclude(Sequel::SQL::BooleanExpression.from_value_pairs(meths.zip([]), :OR))}
3304   else
3305     vals = Array(obj).reject{|o| !meths.all?{|m| o.get_column_value(m)}}
3306     return SQL::Constants::FALSE if vals.empty?
3307     if obj.is_a?(Array)
3308       if keys.length == 1
3309         meth = meths.first
3310         {keys.first=>vals.map{|o| o.get_column_value(meth)}}
3311       else
3312         {keys=>vals.map{|o| meths.map{|m| o.get_column_value(m)}}}
3313       end  
3314     else
3315       keys.zip(meths.map{|k| obj.get_column_value(k)})
3316     end
3317   end
3318   SQL::BooleanExpression.from_value_pairs(vals)
3319 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
3322 def check_association(model, association)
3323   raise(Sequel::UndefinedAssociation, "Invalid association #{association} for #{model.name}") unless reflection = model.association_reflection(association)
3324   raise(Sequel::Error, "Eager loading is not allowed for #{model.name} association #{association}") if reflection[:allow_eager] == false
3325   reflection
3326 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
3330 def eager_graph_check_association(model, association)
3331   if association.is_a?(SQL::AliasedExpression)
3332     expr = association.expression
3333     if expr.is_a?(SQL::Identifier)
3334       expr = expr.value
3335       if expr.is_a?(String)
3336         expr = expr.to_sym
3337       end
3338     end
3339 
3340     SQL::AliasedExpression.new(check_association(model, expr), association.alias || expr, association.columns)
3341   else
3342     check_association(model, association)
3343   end
3344 end
eager_graph_loader() click to toggle source

The EagerGraphLoader instance used for converting eager_graph results.

     # File lib/sequel/model/associations.rb
3347 def eager_graph_loader
3348   unless egl = cache_get(:_model_eager_graph_loader)
3349     egl = cache_set(:_model_eager_graph_loader, EagerGraphLoader.new(self))
3350   end
3351   egl.dup
3352 end
eager_load(a, eager_assoc=@opts[:eager]) click to toggle source

Eagerly load all specified associations

     # File lib/sequel/model/associations.rb
3355 def eager_load(a, eager_assoc=@opts[:eager])
3356   return if a.empty?
3357   # Key is foreign/primary key name symbol.
3358   # Value is hash with keys being foreign/primary key values (generally integers)
3359   # and values being an array of current model objects with that specific foreign/primary key
3360   key_hash = {}
3361   # Reflections for all associations to eager load
3362   reflections = eager_assoc.keys.map{|assoc| model.association_reflection(assoc) || (raise Sequel::UndefinedAssociation, "Model: #{self}, Association: #{assoc}")}
3363       
3364   # Populate the key_hash entry for each association being eagerly loaded
3365   reflections.each do |r|
3366     if key = r.eager_loader_key
3367       # key_hash for this key has already been populated,
3368       # skip populating again so that duplicate values
3369       # aren't added.
3370       unless id_map = key_hash[key]
3371         id_map = key_hash[key] = Hash.new{|h,k| h[k] = []}
3372 
3373         # Supporting both single (Symbol) and composite (Array) keys.
3374         a.each do |rec|
3375           case key
3376           when Array
3377             if (k = key.map{|k2| rec.get_column_value(k2)}) && k.all?
3378               id_map[k] << rec
3379             end
3380           when Symbol
3381             if k = rec.get_column_value(key)
3382               id_map[k] << rec
3383             end
3384           else
3385             raise Error, "unhandled eager_loader_key #{key.inspect} for association #{r[:name]}"
3386           end
3387         end
3388       end
3389     else
3390       id_map = nil
3391     end
3392   
3393     loader = r[:eager_loader]
3394     associations = eager_assoc[r[:name]]
3395     if associations.respond_to?(:call)
3396       eager_block = associations
3397       associations = OPTS
3398     elsif associations.is_a?(Hash) && associations.length == 1 && (pr_assoc = associations.to_a.first) && pr_assoc.first.respond_to?(:call)
3399       eager_block, associations = pr_assoc
3400     end
3401     loader.call(:key_hash=>key_hash, :rows=>a, :associations=>associations, :self=>self, :eager_block=>eager_block, :id_map=>id_map)
3402     a.each{|object| object.send(:run_association_callbacks, r, :after_load, object.associations[r[:name]])} if r[:after_load]
3403   end 
3404 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
3260 def eager_options_for_associations(associations)
3261   opts = {}
3262   associations.flatten.each do |association|
3263     case association
3264     when Symbol
3265       check_association(model, association)
3266       opts[association] = nil
3267     when Hash
3268       association.keys.each{|assoc| check_association(model, assoc)}
3269       opts.merge!(association)
3270     else
3271       raise(Sequel::Error, 'Associations must be in the form of a symbol or hash')
3272     end
3273   end
3274   opts
3275 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
3407 def many_to_many_association_filter_expression(op, ref, obj)
3408   lpks, lks, rks = ref.values_at(:left_primary_key_columns, :left_keys, :right_keys)
3409   jt = ref.join_table_alias
3410   lpks = lpks.first if lpks.length == 1
3411   lpks = ref.qualify(model.table_name, lpks)
3412 
3413   meths = if obj.is_a?(Sequel::Dataset)
3414     ref.qualify(obj.model.table_name, ref.right_primary_keys)
3415   else
3416     ref.right_primary_key_methods
3417   end
3418 
3419   expr = association_filter_key_expression(ref.qualify(jt, rks), meths, obj)
3420   unless expr == SQL::Constants::FALSE
3421     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)))
3422     expr = add_association_filter_conditions(ref, obj, expr)
3423   end
3424 
3425   association_filter_handle_inversion(op, expr, Array(lpks))
3426 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
3430 def many_to_one_association_filter_expression(op, ref, obj)
3431   keys = ref.qualify(model.table_name, ref[:key_columns])
3432   meths = if obj.is_a?(Sequel::Dataset)
3433     ref.qualify(obj.model.table_name, ref.primary_keys)
3434   else
3435     ref.primary_key_methods
3436   end
3437 
3438   expr = association_filter_key_expression(keys, meths, obj)
3439   expr = add_association_filter_conditions(ref, obj, expr)
3440   association_filter_handle_inversion(op, expr, keys)
3441 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/associations.rb
3458 def non_sql_option?(key)
3459   super || key == :eager || key == :eager_graph
3460 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
3444 def one_to_many_association_filter_expression(op, ref, obj)
3445   keys = ref.qualify(model.table_name, ref[:primary_key_columns])
3446   meths = if obj.is_a?(Sequel::Dataset)
3447     ref.qualify(obj.model.table_name, ref[:keys])
3448   else
3449     ref[:key_methods]
3450   end
3451 
3452   expr = association_filter_key_expression(keys, meths, obj)
3453   expr = add_association_filter_conditions(ref, obj, expr)
3454   association_filter_handle_inversion(op, expr, keys)
3455 end
one_to_one_association_filter_expression(op, ref, obj)
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
3464 def post_load(all_records)
3465   eager_graph_build_associations(all_records) if @opts[:eager_graph]
3466   eager_load(all_records) if @opts[:eager] && (row_proc || @opts[:eager_graph])
3467   super
3468 end