Class: GraphQL::Subscriptions

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

Direct Known Subclasses

ActionCableSubscriptions

Defined Under Namespace

Classes: ActionCableSubscriptions, Event, Instrumentation

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(schema:, **rest) ⇒ Subscriptions

Returns a new instance of Subscriptions.



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

def initialize(kwargs)
  @schema = kwargs[:schema]
end

Class Method Details

.use(defn, options = {}) ⇒ Object 



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# File 'lib/graphql/subscriptions.rb', line 10

def self.use(defn, options = {})
  schema = defn.target
  options[:schema] = schema
  schema.subscriptions = self.new(options)
  instrumentation = Subscriptions::Instrumentation.new(schema: schema)
  defn.instrument(:field, instrumentation)
  defn.instrument(:query, instrumentation)
  nil
end

Instance Method Details

#deliver(subscription_id, result, context) ⇒ void

This method returns an undefined value.

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

Parameters:

Raises:

  • (NotImplementedError) 


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# File 'lib/graphql/subscriptions.rb', line 116

def deliver(subscription_id, result, context)
  raise NotImplementedError
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:

  • (NotImplementedError) 


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# File 'lib/graphql/subscriptions.rb', line 98

def each_subscription_id(event)
  raise NotImplementedError
end

#execute(subscription_id, event, object) ⇒ void

This method returns an undefined value.

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 deliver the result.

This is where a queue may be inserted to push updates in the background.

Parameters:

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

    The event which was triggered

  • object (Object) —

    The value for the subscription field



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# File 'lib/graphql/subscriptions.rb', line 61

def execute(subscription_id, event, object)
  # Lookup the saved data for this subscription
  query_data = read_subscription(subscription_id)
  # 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)
  # Re-evaluate the saved query
  result = @schema.execute(
    {
      query: query_string,
      context: context,
      subscription_topic: event.topic,
      operation_name: operation_name,
      variables: variables,
      root_value: object,
    }
  )
  deliver(subscription_id, result)
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 88

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

  • (NotImplementedError) 


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# File 'lib/graphql/subscriptions.rb', line 106

def read_subscription(subscription_id)
  raise NotImplementedError
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)
  • object (Object)
  • scope (Symbol, String) (defaults to: nil) 


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# File 'lib/graphql/subscriptions.rb', line 31

def trigger(event_name, args, object, scope: nil)
  field = @schema.get_field("Subscription", event_name)
  if !field
    raise "No subscription matching trigger: #{event_name}"
  end

  event = Subscriptions::Event.new(
    name: event_name,
    arguments: 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.

Parameters:

Raises:

  • (NotImplementedError) 


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# File 'lib/graphql/subscriptions.rb', line 125

def write_subscription(query, events)
  raise NotImplementedError
end