module GlobalID::Locator

Like .locate, but instead of returning nil or leaking the backend's own exceptions when the record can't be returned, it raises one of two GlobalID-specific errors so callers can tell the cases apart:

• GlobalID::Locator::RecordNotFound when the record no longer exists. Retrying won't help.

• GlobalID::Locator::RecordUnavailable when the record couldn't be located due to any other failure in the backend, like a database connection error. The record may still exist, so retrying may succeed.

The distinction is drawn without knowing the backend's exception classes: the record is looked up through a query that doesn't raise on missing records (like .locate_many's :ignore_missing), so an empty result means the record is gone, while an error from the query itself means the backend is unavailable.

Returns nil for a blank or unparseable GlobalID, or one disallowed by the :only option, just like .locate, and accepts the same options.

Note: custom locators registered with .use need to implement locate_many with support for the :ignore_missing option for this method to work.

# File lib/global_id/locator.rb, line 71
def fetch(gid, options = {})
  gid = GlobalID.parse(gid)

  return unless gid && find_allowed?(gid, options[:only])

  fetch_record(gid, options.except(:only)) or raise RecordNotFound, "Couldn't find record for #{gid}"
end

Takes either a GlobalID or a string that can be turned into a GlobalID

Options:

• :includes - A Symbol, Array, Hash or combination of them. The same structure you would pass into a includes method of Active Record. If present, locate will load all the relationships specified here. See guides.rubyonrails.org/active_record_querying.html#eager-loading-associations.

• :only - A class, module or Array of classes and/or modules that are allowed to be located. Passing one or more classes limits instances of returned classes to those classes or their subclasses. Passing one or more modules in limits instances of returned classes to those including that module. If no classes or modules match, nil is returned.

# File lib/global_id/locator.rb, line 35
def locate(gid, options = {})
  gid = GlobalID.parse(gid)

  return unless gid && find_allowed?(gid, options[:only])

  locator = locator_for(gid)

  if locator.method(:locate).arity == 1
    GlobalID.deprecator.warn "It seems your locator is defining the `locate` method only with one argument. Please make sure your locator is receiving the options argument as well, like `locate(gid, options = {})`."
    locator.locate(gid)
  else
    locator.locate(gid, options.except(:only))
  end
end

Takes an array of GlobalIDs or strings that can be turned into a GlobalIDs. All GlobalIDs must belong to the same app, as they will be located using the same locator using its locate_many method.

By default the GlobalIDs will be located using Model.find(array_of_ids), so the models must respond to that finder signature.

This approach will efficiently call only one find (or where(id: id), when using ignore_missing) per model class, but still interpolate the results to match the order in which the gids were passed.

Options:

• :includes - A Symbol, Array, Hash or combination of them The same structure you would pass into a includes method of Active Record. @see guides.rubyonrails.org/active_record_querying.html#eager-loading-associations If present, locate_many will load all the relationships specified here. Note: It only works if all the gids models have that relationships.

• :only - A class, module or Array of classes and/or modules that are allowed to be located. Passing one or more classes limits instances of returned classes to those classes or their subclasses. Passing one or more modules in limits instances of returned classes to those including that module. If no classes or modules match, nil is returned.

• :ignore_missing - By default, locate_many will call find on the model to locate the ids extracted from the GIDs. In Active Record (and other data stores following the same pattern), find will raise an exception if a named ID can't be found. When you set this option to true, we will use where(id: ids) instead, which does not raise on missing records.

# File lib/global_id/locator.rb, line 104
def locate_many(gids, options = {})
  if (allowed_gids = parse_allowed(gids, options[:only])).any?
    locator = locator_for(allowed_gids.first)
    locator.locate_many(allowed_gids, options)
  else
    []
  end
end

Takes an array of SignedGlobalIDs or strings that can be turned into a SignedGlobalIDs. The SignedGlobalIDs are located using Model.find(array_of_ids), so the models must respond to that finder signature.

This approach will efficiently call only one find per model class, but still interpolate the results to match the order in which the gids were passed.

Options:

• :includes - A Symbol, Array, Hash or combination of them The same structure you would pass into a includes method of Active Record. @see guides.rubyonrails.org/active_record_querying.html#eager-loading-associations If present, locate_many_signed will load all the relationships specified here. Note: It only works if all the gids models have that relationships.

• :only - A class, module or Array of classes and/or modules that are allowed to be located. Passing one or more classes limits instances of returned classes to those classes or their subclasses. Passing one or more modules in limits instances of returned classes to those including that module. If no classes or modules match, nil is returned.

# File lib/global_id/locator.rb, line 147
def locate_many_signed(sgids, options = {})
  locate_many sgids.collect { |sgid| SignedGlobalID.parse(sgid, options.slice(:for)) }.compact, options
end

Takes either a SignedGlobalID or a string that can be turned into a SignedGlobalID

Options:

• :includes - A Symbol, Array, Hash or combination of them The same structure you would pass into a includes method of Active Record. @see guides.rubyonrails.org/active_record_querying.html#eager-loading-associations If present, locate_signed will load all the relationships specified here.

• :only - A class, module or Array of classes and/or modules that are allowed to be located. Passing one or more classes limits instances of returned classes to those classes or their subclasses. Passing one or more modules in limits instances of returned classes to those including that module. If no classes or modules match, nil is returned.

# File lib/global_id/locator.rb, line 125
def locate_signed(sgid, options = {})
  SignedGlobalID.find sgid, options
end

Tie a locator to an app. Useful when different apps collaborate and reference each others' Global IDs.

The locator can be either a block or a class.

Using a block:

GlobalID::Locator.use :foo do |gid, options|
  FooRemote.const_get(gid.model_name).find(gid.model_id)
end

Using a class:

GlobalID::Locator.use :bar, BarLocator.new

class BarLocator
  def locate(gid, options = {})
    @search_client.search name: gid.model_name, id: gid.model_id
  end
end

# File lib/global_id/locator.rb, line 171
def use(app, locator = nil, &locator_block)
  raise ArgumentError, 'No locator provided. Pass a block or an object that responds to #locate.' unless locator || block_given?

  URI::GID.validate_app(app)

  @locators[normalize_app(app)] = locator || BlockLocator.new(locator_block)
end