Class: GraphqlMigrateExecution::DataloaderBatch

Inherits:
DataloaderAll show all
Defined in:
lib/graphql_migrate_execution/dataloader_batch.rb

Overview

These fields return an array of values using Dataloader, based on a method or attribute of ‘object`. They can be migrated to `dataloader_all` calls, using `object.flat_map`.

TODO: This is not quite right yet. It returns a single array instead of an array of arrays.

Instead, this should create an Array of arrays using ‘dataloader.request_all`.

Constant Summary

Constants inherited from Strategy

Strategy::METHODS_TO_RENAME

Instance Method Summary collapse

Methods inherited from Strategy

#initialize, prefix_if_necessary, #run, strategy_name

Constructor Details

This class inherits a constructor from GraphqlMigrateExecution::Strategy

Instance Method Details

#cleanup(field_definition) ⇒ Object 



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# File 'lib/graphql_migrate_execution/dataloader_batch.rb', line 66

def cleanup(field_definition)
  remove_resolver_method(field_definition)
end

#migrate(field_definition) ⇒ Object 



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# File 'lib/graphql_migrate_execution/dataloader_batch.rb', line 13

def migrate(field_definition)
  inject_resolve_keyword(field_definition, :resolve_batch)
  # inject_batch_dataloader_method(field_definition, [:request_all, :load_all], :dataload_all, "flat_map")

  def_node = field_definition.resolver_method.node
  call_node = def_node.body.body.first
  case call_node.name
  when :request_all, :load_all
    load_arg_node = call_node.arguments.arguments.first
    with_node = call_node.receiver
    source_class_node, *source_args_nodes = with_node.arguments
  when :dataload_all
    source_class_node, *source_args_nodes, load_arg_node = call_node.arguments.arguments
  else
    raise ArgumentError, "Unexpected DataloadAll method name: #{def_node.name.inspect}"
  end

  old_load_arg_s = load_arg_node.slice
  new_load_arg_s = case old_load_arg_s
  when "object"
    "object"
  when /object((\.|\[)[:a-zA-Z0-9_\.\"\'\[\]]+)/
    call_chain = $1
    "object#{call_chain}"
  else
    raise ArgumentError, "Failed to transform Dataloader argument: #{old_load_arg_s.inspect}"
  end
  new_source_args = [
    source_class_node.slice,
    *source_args_nodes.map(&:slice)
  ].join(", ")

  old_method_source = def_node.slice_lines
  new_method_source = old_method_source.sub(/def ([a-z_A-Z0-9]+)(\(|$| )/) do
    is_adding_args = $2.size == 0
    "def self.#{$1}#{is_adding_args ? "(" : $2}objects, context#{is_adding_args ? ")" : ", "}"
  end

  old_source_lines = call_node.slice_lines
  leading_whitespace = old_source_lines[/^\s+/]

  new_method_body = <<~RUBY
    #{leading_whitespace}requests = objects.map { |object| context.dataloader.with(#{new_source_args}).request_all(#{new_load_arg_s}) }
    #{leading_whitespace}requests.map! { |reqs| reqs.map!(&:load) } # replace dataloader requests with loaded data
    #{leading_whitespace}requests
  RUBY

  new_method_source.sub!(old_source_lines, new_method_body)

  combined_new_source = new_method_source + "\n" + old_method_source
  @result_source.sub!(old_method_source, combined_new_source)
end