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Extract reifiers/has_many_through

This commit is contained in:
Jared Beck 2016-12-20 14:55:59 -05:00
parent db429d24a0
commit 74cce2d5ce
2 changed files with 104 additions and 96 deletions
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110
lib/paper_trail/reifier.rb
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@ -1,6 +1,7 @@
require "paper_trail/attribute_serializers/object_attribute"
require "paper_trail/reifiers/belongs_to"
require "paper_trail/reifiers/has_many"
require "paper_trail/reifiers/has_many_through"
require "paper_trail/reifiers/has_one"
module PaperTrail
@ -20,6 +21,18 @@ module PaperTrail
model
end
# Restore the `model`'s has_many associations as they were at version_at
# timestamp We lookup the first child versions after version_at timestamp or
# in same transaction.
# @api private
def reify_has_manys(transaction_id, model, options = {})
assoc_has_many_through, assoc_has_many_directly =
model.class.reflect_on_all_associations(:has_many).
partition { |assoc| assoc.options[:through] }
reify_has_many_associations(transaction_id, assoc_has_many_directly, model, options)
reify_has_many_through_associations(transaction_id, assoc_has_many_through, model, options)
end
private
# Given a hash of `options` for `.reify`, return a new hash with default
@ -82,54 +95,6 @@ module PaperTrail
model
end
# Examine the `source_reflection`, i.e. the "source" of `assoc` the
# `ThroughReflection`. The source can be a `BelongsToReflection`
# or a `HasManyReflection`.
#
# If the association is a has_many association again, then call
# reify_has_manys for each record in `through_collection`.
#
# @api private
def hmt_collection(through_collection, assoc, options, transaction_id)
if !assoc.source_reflection.belongs_to? && through_collection.present?
hmt_collection_through_has_many(
through_collection, assoc, options, transaction_id
)
else
hmt_collection_through_belongs_to(
through_collection, assoc, options, transaction_id
)
end
end
# @api private
def hmt_collection_through_has_many(through_collection, assoc, options, transaction_id)
through_collection.each do |through_model|
reify_has_manys(transaction_id, through_model, options)
end
# At this point, the "through" part of the association chain has
# been reified, but not the final, "target" part. To continue our
# example, `model.sections` (including `model.sections.paragraphs`)
# has been loaded. However, the final "target" part of the
# association, that is, `model.paragraphs`, has not been loaded. So,
# we do that now.
through_collection.flat_map { |through_model|
through_model.public_send(assoc.name.to_sym).to_a
}
end
# @api private
def hmt_collection_through_belongs_to(through_collection, assoc, options, tx_id)
ids = through_collection.map { |through_model|
through_model.send(assoc.source_reflection.foreign_key)
}
versions = load_versions_for_hmt_association(assoc, ids, tx_id, options[:version_at])
collection = Array.new assoc.klass.where(assoc.klass.primary_key => ids)
Reifiers::HasMany.prepare_array(collection, options, versions)
collection
end
# Look for attributes that exist in `model` and not in this version.
# These attributes should be set to nil. Modifies `attrs`.
# @api private
@ -150,25 +115,6 @@ module PaperTrail
first
end
# Given a `has_many(through:)` association and an array of `ids`, return
# the version records from the point in time identified by `tx_id` or
# `version_at`.
# @api private
def load_versions_for_hmt_association(assoc, ids, tx_id, version_at)
version_id_subquery = assoc.klass.paper_trail.version_class.
select("MIN(id)").
where("item_type = ?", assoc.class_name).
where("item_id IN (?)", ids).
where(
"created_at >= ? OR transaction_id = ?",
version_at,
tx_id
).
group("item_id").
to_sql
Reifiers::HasMany.versions_by_id(assoc.klass, version_id_subquery)
end
# Reify onto `model` an attribute named `k` with value `v` from `version`.
#
# `ObjectAttribute#deserialize` will return the mapped enum value and in
@ -236,17 +182,6 @@ module PaperTrail
end
end
# Restore the `model`'s has_many associations as they were at version_at
# timestamp We lookup the first child versions after version_at timestamp or
# in same transaction.
def reify_has_manys(transaction_id, model, options = {})
assoc_has_many_through, assoc_has_many_directly =
model.class.reflect_on_all_associations(:has_many).
partition { |assoc| assoc.options[:through] }
reify_has_many_associations(transaction_id, assoc_has_many_directly, model, options)
reify_has_many_through_associations(transaction_id, assoc_has_many_through, model, options)
end
# Reify all direct (not `through`) `has_many` associations of `model`.
# @api private
def reify_has_many_associations(transaction_id, associations, model, options = {})
@ -256,29 +191,12 @@ module PaperTrail
end
end
# Reify a single HMT association of `model`.
# @api private
def reify_has_many_through_association(assoc, model, options, transaction_id)
# Load the collection of through-models. For example, if `model` is a
# Chapter, having many Paragraphs through Sections, then
# `through_collection` will contain Sections.
through_collection = model.send(assoc.options[:through])
# Now, given the collection of "through" models (e.g. sections), load
# the collection of "target" models (e.g. paragraphs)
collection = hmt_collection(through_collection, assoc, options, transaction_id)
# Finally, assign the `collection` of "target" models, e.g. to
# `model.paragraphs`.
model.send(assoc.name).proxy_association.target = collection
end
# Reify all HMT associations of `model`. This must be called after the
# direct (non-`through`) has_manys have been reified.
# @api private
def reify_has_many_through_associations(transaction_id, associations, model, options = {})
each_enabled_association(associations) do |assoc|
reify_has_many_through_association(assoc, model, options, transaction_id)
Reifiers::HasManyThrough.reify(assoc, model, options, transaction_id)
end
end

90
lib/paper_trail/reifiers/has_many_through.rb Normal file
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@ -0,0 +1,90 @@
module PaperTrail
module Reifiers
# Reify a single HMT association of `model`.
# @api private
module HasManyThrough
class << self
# @api private
def reify(assoc, model, options, transaction_id)
# Load the collection of through-models. For example, if `model` is a
# Chapter, having many Paragraphs through Sections, then
# `through_collection` will contain Sections.
through_collection = model.send(assoc.options[:through])
# Now, given the collection of "through" models (e.g. sections), load
# the collection of "target" models (e.g. paragraphs)
collection = collection(through_collection, assoc, options, transaction_id)
# Finally, assign the `collection` of "target" models, e.g. to
# `model.paragraphs`.
model.send(assoc.name).proxy_association.target = collection
end
private
# Examine the `source_reflection`, i.e. the "source" of `assoc` the
# `ThroughReflection`. The source can be a `BelongsToReflection`
# or a `HasManyReflection`.
#
# If the association is a has_many association again, then call
# reify_has_manys for each record in `through_collection`.
#
# @api private
def collection(through_collection, assoc, options, transaction_id)
if !assoc.source_reflection.belongs_to? && through_collection.present?
collection_through_has_many(through_collection, assoc, options, transaction_id)
else
collection_through_belongs_to(through_collection, assoc, options, transaction_id)
end
end
# @api private
def collection_through_has_many(through_collection, assoc, options, transaction_id)
through_collection.each do |through_model|
::PaperTrail::Reifier.reify_has_manys(transaction_id, through_model, options)
end
# At this point, the "through" part of the association chain has
# been reified, but not the final, "target" part. To continue our
# example, `model.sections` (including `model.sections.paragraphs`)
# has been loaded. However, the final "target" part of the
# association, that is, `model.paragraphs`, has not been loaded. So,
# we do that now.
through_collection.flat_map { |through_model|
through_model.public_send(assoc.name.to_sym).to_a
}
end
# @api private
def collection_through_belongs_to(through_collection, assoc, options, tx_id)
ids = through_collection.map { |through_model|
through_model.send(assoc.source_reflection.foreign_key)
}
versions = load_versions_for_hmt_association(assoc, ids, tx_id, options[:version_at])
collection = Array.new assoc.klass.where(assoc.klass.primary_key => ids)
Reifiers::HasMany.prepare_array(collection, options, versions)
collection
end
# Given a `has_many(through:)` association and an array of `ids`, return
# the version records from the point in time identified by `tx_id` or
# `version_at`.
# @api private
def load_versions_for_hmt_association(assoc, ids, tx_id, version_at)
version_id_subquery = assoc.klass.paper_trail.version_class.
select("MIN(id)").
where("item_type = ?", assoc.class_name).
where("item_id IN (?)", ids).
where(
"created_at >= ? OR transaction_id = ?",
version_at,
tx_id
).
group("item_id").
to_sql
Reifiers::HasMany.versions_by_id(assoc.klass, version_id_subquery)
end
end
end
end
end