Method: ROM::Relation::ClassInterface#view

Defined in:
lib/rom/relation/class_interface.rb

#view(name, schema, &block) ⇒ Symbol #view(name, &block) ⇒ Symbol

Define a relation view with a specific schema

This method should only be used in cases where a given adapter doesn’t support automatic schema projection at run-time.

**It’s not needed in rom-sql**

Overloads:

  • #view(name, schema, &block) ⇒ Symbol

    Examples:

    View with the canonical schema

    class Users < ROM::Relation[:sql]
  view(:listing, schema) do
    order(:name)
  end
end

    View with a projected schema

    class Users < ROM::Relation[:sql]
  view(:listing, schema.project(:id, :name)) do
    order(:name)
  end
end
  • #view(name, &block) ⇒ Symbol

    Examples:

    View with the canonical schema and arguments

    class Users < ROM::Relation[:sql]
  view(:by_name) do |name|
    where(name: name)
  end
end

    View with projected schema and arguments

    class Users < ROM::Relation[:sql]
  view(:by_name) do
    schema { project(:id, :name) }
    relation { |name| where(name: name) }
  end
end

    View with a schema extended with foreign attributes

    class Users < ROM::Relation[:sql]
  view(:index) do
    schema { append(relations[:tasks][:title]) }
    relation { |name| where(name: name) }
  end
end

Returns:

  • (Symbol) —

    view method name



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# File 'lib/rom/relation/class_interface.rb', line 187

def view(*args, &block)
  if args.size == 1 && block.arity > 0
    raise ArgumentError, "schema attribute names must be provided as the second argument"
  end

  name, new_schema_fn, relation_block =
    if args.size == 1
      ViewDSL.new(*args, schema, &block).call
    else
      [*args, block]
    end

  schemas[name] =
    if args.size == 2
      -> _ { schema.project(*args[1]) }
    else
      new_schema_fn
    end

  if relation_block.arity > 0
    auto_curry_guard do
      define_method(name, &relation_block)

      auto_curry(name) do
        schemas[name].(self)
      end
    end
  else
    define_method(name) do
      schemas[name].(instance_exec(&relation_block))
    end
  end

  name
end