schema(infer: true) overrides command's input

[Kukunin]

In my application, I have different attributes format between schema (legacy tables) and my domain models. So I need to use mappers to both save and restore an entity.

While it's easy to use mappers for Relation, I haven't found a way to use for Command. So, I use command's input for this purpose.

It works great, until I want to set association for my relation. schema(infer: true) breaks everything.

After some investigation, I've found that inferred schema overrides my custom input for any commands.

So, without schema(infer: true), I get custom mapper as input

From: /Users/kukunin/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/rom-sql-0.8.0/lib/rom/sql/commands/create.rb @ line 24 ROM::SQL::Commands::Create#execute:

    22: def execute(tuples)
    23:   insert_tuples = with_input_tuples(tuples) do |tuple|
 => 24:     attributes = input[tuple]
    25:     validator.call(attributes)
    26:     attributes.to_h
    27:   end
    28:
    29:   if insert_tuples.length > 1
    30:     multi_insert(insert_tuples)
    31:   else
    32:     insert(insert_tuples)
    33:   end
    34: end

[6] pry(#<Persistence::Commands::Hoi::CreateCaseFromModel>)> input
=> #<Method: Persistence::Mappers::Hoi::CasesTuple#to_tuple>

But with schema(infer: true), it is:

[5] pry(#<Persistence::Commands::Hoi::CreateCaseFromModel>)> input
=> #<Dry::Types::Constructor type=#<Dry::Types::Hash::Schema primitive=Hash options={:member_types=>{:id=>#<Dry::Types::Constrained type=#<Dry::Types::Definition primitive=Integer options={}> options={:rule=>#<Dry::Logic::Operations::And rules=[#<Dry::Logic::Rule::Predicate predicate=#<Method: Module(Dry::Logic::Predicates::Methods)#type?> options={:args=>[Integer]}>, #<Dry::Logic::Rule::Predicate predicate=#<Method: Module(Dry::Logic::Predicates::Methods)#gt?> options={:args=>[0]}>] options={}>, :meta=>{:primary_key=>true, :name=>:id}}.....A LOT OF TEXT

So, because It doesn't map my domain entity, it crashes.

My relation:

      class Relations::Cases < ROM::Relation[:sql]
        register_as :hoi_cases
        dataset :cases
      end

and command with custom mapper:

      class Commands::CreateCaseFromModel < ROM::Command::Create[:sql]
        relation :hoi_cases
        register_as :create_from_model

        input Mappers::CasesTuple.build.method(:to_tuple)
      end

and just for clarity, my mapper code:

      class CasesTuple < ROM::Mapper
        relation :hoi_quotes
        register_as :tuple

        # mapping rules here

        def to_tuple(params)
          call([params]).first
        end
      end

P.S. If you know a better way to map entity to underlying schema in 2-directions more easily - tell me, please.

Thanks!

[solnic]

We can tweak commands in a way that if there's an input handler configured which is not the default proc, then we'll compose it with the schema handler. Would that work?

[flash-gordon]

This is possible to override Command.build method in this way

      class Commands::CreateCaseFromModel < ROM::Command::Create[:sql]
        relation :hoi_cases
        register_as :create_from_model

        def self.build(relation, options = {})
          # pass any input you want, you can access schema's input via relation.schema_hash
          super(relation, options.merge(input: ...)) 
        end
      end

This will do the trick for now ^ But I agree we need to make it more user-friendly :)
See sources: https://github.com/rom-rb/rom/blob/master/lib/rom/plugins/command/schema.rb#L16

[solnic]

This issue was moved to rom-rb/rom#360