Class: ViewModel::Migrator

Inherits:
Object
  • Object
show all
Defined in:
lib/view_model/migrator.rb

Direct Known Subclasses

DownMigrator, UpMigrator

Constant Summary collapse

EXCLUDE_FROM_MIGRATION = 
'_exclude_from_migration'

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(required_versions) ⇒ Migrator

Returns a new instance of Migrator.



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# File 'lib/view_model/migrator.rb', line 26

def initialize(required_versions)
  @paths = required_versions.each_with_object({}) do |(viewmodel_class, required_version), h|
    if required_version != viewmodel_class.schema_version
      path = viewmodel_class.migration_path(from: required_version, to: viewmodel_class.schema_version)
      h[viewmodel_class.view_name] = path
    end
  end

  @versions = required_versions.each_with_object({}) do |(viewmodel_class, required_version), h|
    h[viewmodel_class.view_name] = [required_version, viewmodel_class.schema_version]
  end
end

Class Method Details

.migrated_deep_schema_version(viewmodel_class, required_versions, include_referenced: true) ⇒ Object 



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# File 'lib/view_model/migrator.rb', line 8

def migrated_deep_schema_version(viewmodel_class, required_versions, include_referenced: true)
  deep_schema_version = viewmodel_class.deep_schema_version(include_referenced: include_referenced)

  if required_versions.present?
    deep_schema_version = deep_schema_version.dup

    required_versions.each do |required_vm_class, required_version|
      name = required_vm_class.view_name
      if deep_schema_version.has_key?(name)
        deep_schema_version[name] = required_version
      end
    end
  end

  deep_schema_version
end

Instance Method Details

#migrate!(serialization) ⇒ Object 



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# File 'lib/view_model/migrator.rb', line 39

def migrate!(serialization)
  references = (serialization['references'] ||= {})

  # First visit everything except references; there's no issue with adding
  # new references during this.
  migrate_tree!(serialization.except('references'), references: references)

  # While visiting references itself, we need to take care that we can
  # concurrently modify them (e.g. by adding new referenced views).
  # Moreover, such added references must themselves be visited, as they'll
  # be synthesized at the current version and so may need to be migrated
  # down to the client's requested version.
  visited_refs = []
  loop do
    unvisited_refs = references.keys - visited_refs
    break if unvisited_refs.empty?

    unvisited_refs.each do |ref|
      migrate_tree!(references[ref], references: references)
    end

    visited_refs.concat(unvisited_refs)
  end

  GarbageCollection.garbage_collect_references!(serialization)

  if references.empty?
    serialization.delete('references')
  end
end