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/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 Classes: ActionCableSubscriptions, BroadcastAnalyzer, DefaultSubscriptionResolveExtension, Event, Instrumentation, InvalidTriggerError, SubscriptionScopeMissingError

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

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

Returns a new instance of Subscriptions.

Parameters:

  • schema (Class) —

    the GraphQL schema this manager belongs to

  • validate_update (Boolean) (defaults to: true) —

    If false, then validation is skipped when executing updates



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# File 'lib/graphql/subscriptions.rb', line 43

def initialize(schema:, validate_update: true, broadcast: false, default_broadcastable: false, **rest)
  if broadcast
    schema.query_analyzer(Subscriptions::BroadcastAnalyzer)
  end
  @default_broadcastable = default_broadcastable
  @schema = schema
  @validate_update = validate_update
end

Instance Attribute Details

#default_broadcastable ⇒ Boolean (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 53

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 26

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

  if schema.subscriptions(inherited: false)
    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)
  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 231

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_id ⇒ String

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 214

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 209

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 192

def deliver(subscription_id, result)
  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 163

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:

Raises:



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# File 'lib/graphql/subscriptions.rb', line 175

def execute_all(event, object)
  raise GraphQL::RequiredImplementationMissingError
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 107

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)
  execute_options = {
    query: query_string,
    context: context,
    subscription_topic: event.topic,
    operation_name: operation_name,
    variables: variables,
    root_value: object,
  }
  
   # merge event's and query's context together
  context.merge!(event.context) unless event.context.nil? || context.nil?
  
  execute_options[:validate] = validate_update?(**execute_options)
  result = @schema.execute(**execute_options)
  subscriptions_context = result.context.namespace(:subscriptions)
  if subscriptions_context[:no_update]
    result = nil
  end

  unsubscribed = subscriptions_context[:unsubscribed]

  if unsubscribed
    # `unsubscribe` was called, clean up on our side
    # TODO also send `{more: false}` to client?
    delete_subscription(subscription_id)
    result = nil
  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 226

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 183

def read_subscription(subscription_id)
  raise GraphQL::RequiredImplementationMissingError
end

#trigger(event_name, args, object, scope: nil, context: {}) ⇒ 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<String, Symbol => Object]

  • object (Object)
  • scope (Symbol, String) (defaults to: nil)
  • context (Hash) (defaults to: {}) 


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# File 'lib/graphql/subscriptions.rb', line 63

def trigger(event_name, args, object, scope: nil, context: {})
  # Make something as context-like as possible, even though there isn't a current query:
  dummy_query = GraphQL::Query.new(@schema, "", validate: false, context: context)
  context = dummy_query.context
  event_name = event_name.to_s

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

  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, context)
    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
  # Should this accept a real context somehow?
  normalized_args = normalize_arguments(normalized_event_name, field, args, GraphQL::Query::NullContext)

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

#validate_update?(query:, context:, root_value:, subscription_topic:, operation_name:, variables:) ⇒ Boolean

Define this method to customize whether to validate this subscription when executing an update.

Returns:

  • (Boolean) —

    defaults to true, or false if validate: false is provided.



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# File 'lib/graphql/subscriptions.rb', line 155

def validate_update?(query:, context:, root_value:, subscription_topic:, operation_name:, variables:)
  @validate_update
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.

Parameters:

Raises:



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# File 'lib/graphql/subscriptions.rb', line 201

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