Preserve types transform

[mpraglowski]

No description provided.

[swistak35]

I like that 👍

[mostlyobvious]

can we make an assumption on Metadata being always in an Event?

[mpraglowski]

With RubyEventStore::Event this assumption is always true because of its initializer implementation

    def initialize(event_id: SecureRandom.uuid, metadata: nil, data: {})
      @event_id = event_id.to_s
      @metadata = Metadata.new(metadata.to_h)
      @data     = data
    end

If we prepare event with nil metadata (or use another event class that allows that) we will get:

> e = RubyEventStore::Event.new
=> #<RubyEventStore::Event:0x00007fc630389408 @event_id="2755b447-78d1-4dad-aec3-29792a9b6567", @metad...

> e.metadata
=> #<RubyEventStore::Metadata:0x00007fc630388eb8 @h={}>

> e.instance_variable_set("@metadata", nil)
=> nil
> e.metadata
=> nil

> c = RubyEventStore::Client.new(repository: RubyEventStore::InMemoryRepository.new)
=> #<RubyEventStore::Client:0xb4>

> c.publish(e)
Traceback (most recent call last):
       9: from /Users/mpraglowski/.rbenv/versions/2.7.2/bin/irb:23:in `<main>'
       8: from /Users/mpraglowski/.rbenv/versions/2.7.2/bin/irb:23:in `load'
       7: from /Users/mpraglowski/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/irb-1.2.6/exe/irb:11:in `<top (required)>'
       6: from (irb):13
       5: from /Users/mpraglowski/arkency/rails_event_store/ruby_event_store/lib/ruby_event_store/client.rb:32:in `publish'
       4: from /Users/mpraglowski/arkency/rails_event_store/ruby_event_store/lib/ruby_event_store/client.rb:341:in `enrich_events_metadata'
       3: from /Users/mpraglowski/arkency/rails_event_store/ruby_event_store/lib/ruby_event_store/client.rb:341:in `each'
       2: from /Users/mpraglowski/arkency/rails_event_store/ruby_event_store/lib/ruby_event_store/client.rb:341:in `block in enrich_events_metadata'
       1: from /Users/mpraglowski/arkency/rails_event_store/ruby_event_store/lib/ruby_event_store/client.rb:347:in `enrich_event_metadata'
NoMethodError (undefined method `[]' for nil:NilClass)

So here in transformations I could assume metadata are present. The question is if I should make such assumptions for both data & metadata ;)

[mpraglowski]

BTW this works because:

> nil.respond_to?(:[])
=> false