Class: Sequent::Core::AggregateRepository
- Inherits:
-
Object
- Object
- Sequent::Core::AggregateRepository
- Defined in:
- lib/sequent/core/aggregate_repository.rb
Overview
Repository for aggregates.
Implements the Unit-Of-Work and Identity-Map patterns to ensure each aggregate is only loaded once per transaction and that you always get the same aggregate instance back.
On commit all aggregates associated with the Unit-Of-Work are queried for uncommitted events. After persisting these events the uncommitted events are cleared from the aggregate.
The repository keeps track of the Unit-Of-Work per thread, so can be shared between threads.
Defined Under Namespace
Classes: AggregateNotFound, HasUncommittedEvents, NonUniqueAggregateId
Constant Summary collapse
- AGGREGATES_KEY =
Key used in thread local
'Sequent::Core::AggregateRepository::aggregates'.to_sym
Instance Method Summary collapse
-
#add_aggregate(aggregate) ⇒ Object
Adds the given aggregate to the repository (or unit of work).
-
#clear ⇒ Object
Clears the Unit of Work.
-
#clear! ⇒ Object
Clears the Unit of Work.
-
#commit(command) ⇒ Object
Gets all uncommitted_events from the ‘registered’ aggregates and stores them in the event store.
-
#contains_aggregate?(aggregate_id) ⇒ Boolean
Returns whether the event store has an aggregate with the given id.
-
#ensure_exists(aggregate_id, clazz) ⇒ Object
Throws exception if not exists.
-
#load_aggregate(aggregate_id, clazz = nil) ⇒ Object
Loads aggregate by given id and class Returns the one in the current Unit Of Work otherwise loads it from history.
-
#load_aggregate_for_snapshotting(aggregate_id, clazz = nil, load_until: nil) ⇒ Object
Optimised for loading lots of events and ignore snapshot events.
-
#load_aggregates(aggregate_ids, clazz = nil) ⇒ Object
Loads multiple aggregates at once.
Instance Method Details
#add_aggregate(aggregate) ⇒ Object
Adds the given aggregate to the repository (or unit of work).
Only when commit
is called all aggregates in the unit of work are ‘processed’ and all uncammited_events are stored in the event_store
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# File 'lib/sequent/core/aggregate_repository.rb', line 40 def add_aggregate(aggregate) existing = aggregates[aggregate.id] if existing && !existing.equal?(aggregate) fail NonUniqueAggregateId.new(aggregate, aggregates[aggregate.id]) else aggregates[aggregate.id] = aggregate end end |
#clear ⇒ Object
Clears the Unit of Work.
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# File 'lib/sequent/core/aggregate_repository.rb', line 164 def clear Thread.current[AGGREGATES_KEY] = nil end |
#clear! ⇒ Object
Clears the Unit of Work.
A HasUncommittedEvents
is raised when there are uncommitted_events in the Unit of Work.
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# File 'lib/sequent/core/aggregate_repository.rb', line 171 def clear! fail HasUncommittedEvents if aggregates.values.any? { |x| !x.uncommitted_events.empty? } clear end |
#commit(command) ⇒ Object
Gets all uncommitted_events from the ‘registered’ aggregates and stores them in the event store.
The events given to the EventStore are ordered in loading order of the different AggregateRoot’s. So Events are stored (and therefore published) in order in which they are ‘apply`-ed per AggregateRoot.
The command is ‘attached’ for traceability purpose so we can see which command resulted in which events.
This is all abstracted away if you use the Sequent::Core::CommandService
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# File 'lib/sequent/core/aggregate_repository.rb', line 152 def commit(command) updated_aggregates = aggregates.values.reject { |x| x.uncommitted_events.empty? } return if updated_aggregates.empty? streams_with_events = updated_aggregates.map do |aggregate| [aggregate.event_stream, aggregate.uncommitted_events] end updated_aggregates.each(&:clear_events) store_events command, streams_with_events end |
#contains_aggregate?(aggregate_id) ⇒ Boolean
Returns whether the event store has an aggregate with the given id
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# File 'lib/sequent/core/aggregate_repository.rb', line 135 def contains_aggregate?(aggregate_id) Sequent.configuration.event_store.stream_exists?(aggregate_id) && Sequent.configuration.event_store.events_exists?(aggregate_id) end |
#ensure_exists(aggregate_id, clazz) ⇒ Object
Throws exception if not exists.
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# File 'lib/sequent/core/aggregate_repository.rb', line 50 def ensure_exists(aggregate_id, clazz) !load_aggregate(aggregate_id, clazz).nil? end |
#load_aggregate(aggregate_id, clazz = nil) ⇒ Object
Loads aggregate by given id and class Returns the one in the current Unit Of Work otherwise loads it from history.
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# File 'lib/sequent/core/aggregate_repository.rb', line 56 def load_aggregate(aggregate_id, clazz = nil) load_aggregates([aggregate_id], clazz)[0] end |
#load_aggregate_for_snapshotting(aggregate_id, clazz = nil, load_until: nil) ⇒ Object
Optimised for loading lots of events and ignore snapshot events. To get the correct historical state of an AggregateRoot it is necessary to be able to ignore snapshots. For a nested AggregateRoot, there will not be a sequence number known, so a load_until timestamp can be used instead.
aggregate_id
The id of the aggregate to be loaded
clazz
Optional argument that checks if aggregate is of type clazz
load_until
Optional argument that defines up until what point in time the AggregateRoot will be rebuilt.
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# File 'lib/sequent/core/aggregate_repository.rb', line 69 def load_aggregate_for_snapshotting(aggregate_id, clazz = nil, load_until: nil) fail ArgumentError, 'aggregate_id is required' if aggregate_id.blank? stream = Sequent .configuration .event_store .find_event_stream(aggregate_id) aggregate = Class.const_get(stream.aggregate_type).stream_from_history(stream) Sequent .configuration .event_store .stream_events_for_aggregate(aggregate_id, load_until: load_until) do |event_stream| aggregate.stream_from_history(event_stream) end if clazz fail TypeError, "#{aggregate.class} is not a #{clazz}" unless aggregate.class <= clazz end aggregate end |
#load_aggregates(aggregate_ids, clazz = nil) ⇒ Object
Loads multiple aggregates at once. Returns the ones in the current Unit Of Work otherwise loads it from history.
Note: This will load all the aggregates in memory, so querying 100s of aggregates with 100s of events could cause memory issues.
Returns all aggregates or raises AggregateNotFound
If clazz
is given and one of the aggregates is not of the correct type a TypeError
is raised.
aggregate_ids
The ids of the aggregates to be loaded clazz
Optional argument that checks if all aggregates are of type clazz
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# File 'lib/sequent/core/aggregate_repository.rb', line 104 def load_aggregates(aggregate_ids, clazz = nil) fail ArgumentError, 'aggregate_ids is required' unless aggregate_ids return [] if aggregate_ids.empty? unique_ids = aggregate_ids.uniq result = aggregates.values_at(*unique_ids).compact query_ids = unique_ids - result.map(&:id) result += Sequent.configuration.event_store.load_events_for_aggregates(query_ids).map do |stream, events| aggregate_class = Class.const_get(stream.aggregate_type) aggregate_class.load_from_history(stream, events) end if result.count != unique_ids.count missing_aggregate_ids = unique_ids - result.map(&:id) fail AggregateNotFound, missing_aggregate_ids end if clazz result.each do |aggregate| fail TypeError, "#{aggregate.class} is not a #{clazz}" unless aggregate.class <= clazz end end result.map do |aggregate| aggregates[aggregate.id] = aggregate end end |