Class: GraphQL::Subscriptions

Inherits:
Object
  • Object
show all
Defined in:
lib/graphql/subscriptions.rb,
lib/graphql/subscriptions/event.rb,
lib/graphql/subscriptions/serialize.rb,
lib/graphql/subscriptions/instrumentation.rb,
lib/graphql/subscriptions/subscription_root.rb,
lib/graphql/subscriptions/broadcast_analyzer.rb,
lib/graphql/subscriptions/action_cable_subscriptions.rb,
lib/graphql/subscriptions/default_subscription_resolve_extension.rb

Direct Known Subclasses

ActionCableSubscriptions

Defined Under Namespace

Modules: Serialize, SubscriptionRoot Classes: ActionCableSubscriptions, BroadcastAnalyzer, DefaultSubscriptionResolveExtension, Event, Instrumentation, InvalidTriggerError

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(schema:, broadcast: false, default_broadcastable: false, **rest) ⇒ Subscriptions

Returns a new instance of Subscriptions.

Parameters:

  • schema (Class)

    the GraphQL schema this manager belongs to


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# File 'lib/graphql/subscriptions.rb', line 37

def initialize(schema:, broadcast: false, default_broadcastable: false, **rest)
  if broadcast
    if !schema.using_ast_analysis?
      raise ArgumentError, "`broadcast: true` requires AST analysis, add `using GraphQL::Analysis::AST` to your schema or see https://graphql-ruby.org/queries/ast_analysis.html."
    end
    schema.query_analyzer(Subscriptions::BroadcastAnalyzer)
  end
  @default_broadcastable = default_broadcastable
  @schema = schema
end

Instance Attribute Details

#default_broadcastableBoolean (readonly)

Returns Used when fields don't have broadcastable: explicitly set.

Returns:

  • (Boolean)

    Used when fields don't have broadcastable: explicitly set


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# File 'lib/graphql/subscriptions.rb', line 49

def default_broadcastable
  @default_broadcastable
end

Class Method Details

.use(defn, options = {}) ⇒ Object

See Also:

  • for options, concrete implementations may add options.

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# File 'lib/graphql/subscriptions.rb', line 20

def self.use(defn, options = {})
  schema = defn.is_a?(Class) ? defn : defn.target

  if schema.subscriptions
    raise ArgumentError, "Can't reinstall subscriptions. #{schema} is using #{schema.subscriptions}, can't also add #{self}"
  end

  instrumentation = Subscriptions::Instrumentation.new(schema: schema)
  defn.instrument(:query, instrumentation)
  defn.instrument(:field, instrumentation)
  options[:schema] = schema
  schema.subscriptions = self.new(**options)
  schema.add_subscription_extension_if_necessary
  nil
end

Instance Method Details

#broadcastable?(query_str, **query_options) ⇒ Boolean

Returns if true, then a query like this one would be broadcasted.

Returns:

  • (Boolean)

    if true, then a query like this one would be broadcasted


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# File 'lib/graphql/subscriptions.rb', line 222

def broadcastable?(query_str, **query_options)
  query = GraphQL::Query.new(@schema, query_str, **query_options)
  if !query.valid?
    raise "Invalid query: #{query.validation_errors.map(&:to_h).inspect}"
  end
  GraphQL::Analysis::AST.analyze_query(query, @schema.query_analyzers)
  query.context.namespace(:subscriptions)[:subscription_broadcastable]
end

#build_idString

Returns A new unique identifier for a subscription.

Returns:

  • (String)

    A new unique identifier for a subscription


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# File 'lib/graphql/subscriptions.rb', line 205

def build_id
  SecureRandom.uuid
end

#delete_subscription(subscription_id) ⇒ Object

A subscription was terminated server-side. Clean up the database.

Parameters:

  • subscription_id (String)

Returns:

  • void.

Raises:


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# File 'lib/graphql/subscriptions.rb', line 200

def delete_subscription(subscription_id)
  raise GraphQL::RequiredImplementationMissingError
end

#deliver(subscription_id, result) ⇒ void

This method returns an undefined value.

A subscription query was re-evaluated, returning result. The result should be send to subscription_id.

Parameters:

  • subscription_id (String)
  • result (Hash)

Raises:


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# File 'lib/graphql/subscriptions.rb', line 183

def deliver(subscription_id, result)
  raise GraphQL::RequiredImplementationMissingError
end

#each_subscription_id(event) {|subscription_id| ... } ⇒ void

This method returns an undefined value.

Get each subscription_id subscribed to event.topic and yield them

Parameters:

Yield Parameters:

  • subscription_id (String)

Raises:


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# File 'lib/graphql/subscriptions.rb', line 166

def each_subscription_id(event)
  raise GraphQL::RequiredImplementationMissingError
end

#execute(subscription_id, event, object) ⇒ void

This method returns an undefined value.

Run the update query for this subscription and deliver it

See Also:

  • GraphQL::Subscriptions.{{#execute_update}
  • GraphQL::Subscriptions.{{#deliver}

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# File 'lib/graphql/subscriptions.rb', line 144

def execute(subscription_id, event, object)
  res = execute_update(subscription_id, event, object)
  if !res.nil?
    deliver(subscription_id, res)
  end
end

#execute_all(event, object) ⇒ void

This method returns an undefined value.

Event event occurred on object, Update all subscribers.

Parameters:


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# File 'lib/graphql/subscriptions.rb', line 156

def execute_all(event, object)
  each_subscription_id(event) do |subscription_id|
    execute(subscription_id, event, object)
  end
end

#execute_update(subscription_id, event, object) ⇒ GraphQL::Query::Result

event was triggered on object, and subscription_id was subscribed, so it should be updated.

Load subscription_id's GraphQL data, re-evaluate the query and return the result.

Parameters:

  • subscription_id (String)
  • event (GraphQL::Subscriptions::Event)

    The event which was triggered

  • object (Object)

    The value for the subscription field

Returns:


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# File 'lib/graphql/subscriptions.rb', line 97

def execute_update(subscription_id, event, object)
  # Lookup the saved data for this subscription
  query_data = read_subscription(subscription_id)
  if query_data.nil?
    delete_subscription(subscription_id)
    return nil
  end

  # Fetch the required keys from the saved data
  query_string = query_data.fetch(:query_string)
  variables = query_data.fetch(:variables)
  context = query_data.fetch(:context)
  operation_name = query_data.fetch(:operation_name)
  result = nil
  # this will be set to `false` unless `.execute` is terminated
  # with a `throw :graphql_subscription_unsubscribed`
  unsubscribed = true
  catch(:graphql_subscription_unsubscribed) do
    catch(:graphql_no_subscription_update) do
      # Re-evaluate the saved query,
      # but if it terminates early with a `throw`,
      # it will stay `nil`
      result = @schema.execute(
        query: query_string,
        context: context,
        subscription_topic: event.topic,
        operation_name: operation_name,
        variables: variables,
        root_value: object,
      )
    end
    unsubscribed = false
  end

  if unsubscribed
    # `unsubscribe` was called, clean up on our side
    # TODO also send `{more: false}` to client?
    delete_subscription(subscription_id)
  end

  result
end

#normalize_name(event_or_arg_name) ⇒ String

Convert a user-provided event name or argument to the equivalent in GraphQL.

By default, it converts the identifier to camelcase. Override this in a subclass to change the transformation.

Parameters:

  • event_or_arg_name (String, Symbol)

Returns:

  • (String)

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# File 'lib/graphql/subscriptions.rb', line 217

def normalize_name(event_or_arg_name)
  Schema::Member::BuildType.camelize(event_or_arg_name.to_s)
end

#read_subscription(subscription_id) ⇒ Hash

The system wants to send an update to this subscription. Read its data and return it.

Parameters:

  • subscription_id (String)

Returns:

  • (Hash)

    Containing required keys

Raises:


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# File 'lib/graphql/subscriptions.rb', line 174

def read_subscription(subscription_id)
  raise GraphQL::RequiredImplementationMissingError
end

#trigger(event_name, args, object, scope: nil) ⇒ void

This method returns an undefined value.

Fetch subscriptions matching this field + arguments pair And pass them off to the queue.

Parameters:

  • event_name (String)
  • args (Hash<String, Symbol => Object])

    rgs [Hash Object]

  • object (Object)
  • scope (Symbol, String) (defaults to: nil)

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# File 'lib/graphql/subscriptions.rb', line 58

def trigger(event_name, args, object, scope: nil)
  event_name = event_name.to_s

  # Try with the verbatim input first:
  field = @schema.get_field(@schema.subscription, event_name)

  if field.nil?
    # And if it wasn't found, normalize it:
    normalized_event_name = normalize_name(event_name)
    field = @schema.get_field(@schema.subscription, normalized_event_name)
    if field.nil?
      raise InvalidTriggerError, "No subscription matching trigger: #{event_name} (looked for #{@schema.subscription.graphql_name}.#{normalized_event_name})"
    end
  else
    # Since we found a field, the original input was already normalized
    normalized_event_name = event_name
  end

  # Normalize symbol-keyed args to strings, try camelizing them
  normalized_args = normalize_arguments(normalized_event_name, field, args)

  event = Subscriptions::Event.new(
    name: normalized_event_name,
    arguments: normalized_args,
    field: field,
    scope: scope,
  )
  execute_all(event, object)
end

#write_subscription(query, events) ⇒ void

This method returns an undefined value.

query was executed and found subscriptions to events. Update the database to reflect this new state.


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# File 'lib/graphql/subscriptions.rb', line 192

def write_subscription(query, events)
  raise GraphQL::RequiredImplementationMissingError
end