class Google::Cloud::Firestore::QueryListener

# QueryListener

An ongoing listen operation on a query. This is returned by calling {Query#listen}.

@example

require "google/cloud/firestore"

firestore = Google::Cloud::Firestore.new

# Create a query
query = firestore.col(:cities).order(:population, :desc)

listener = query.listen do |snapshot|
  puts "The query snapshot has #{snapshot.docs.count} documents "
  puts "and has #{snapshot.changes.count} changes."
end

# When ready, stop the listen operation and close the stream.
listener.stop

Public Class Methods

new(query, &callback) click to toggle source

@private Creates the watch stream and listener object.

Calls superclass method
# File lib/google/cloud/firestore/query_listener.rb, line 48
def initialize query, &callback
  super() # to init MonitorMixin

  @query = query
  raise ArgumentError if @query.nil?

  @callback = callback
  raise ArgumentError if @callback.nil?
  @error_callbacks = []

  @listener = Watch::Listener.for_query self, query, &callback
end

Public Instance Methods

error!(error) click to toggle source

@private Pass the error to user-provided error callbacks.

# File lib/google/cloud/firestore/query_listener.rb, line 189
def error! error
  error_callbacks = synchronize do
    @last_error = error
    @error_callbacks.dup
  end
  error_callbacks.each { |error_callback| error_callback.call error }
end
last_error() click to toggle source

The most recent unhandled error to occur while listening for changes.

If an unhandled error has occurred the listener will attempt to recover from the error and resume listening.

@return [Exception, nil] error The most recent error raised.

@example

require "google/cloud/firestore"

firestore = Google::Cloud::Firestore.new

# Create a query
query = firestore.col(:cities).order(:population, :desc)

listener = query.listen do |snapshot|
  puts "The query snapshot has #{snapshot.docs.count} documents "
  puts "and has #{snapshot.changes.count} changes."
end

# If an error was raised, it can be retrieved here:
listener.last_error #=> nil

# When ready, stop the listen operation and close the stream.
listener.stop
# File lib/google/cloud/firestore/query_listener.rb, line 184
def last_error
  synchronize { @last_error }
end
on_error(&block) click to toggle source

Register to be notified of errors when raised.

If an unhandled error has occurred the listener will attempt to recover from the error and resume listening.

Multiple error handlers can be added.

@yield [callback] The block to be called when an error is raised. @yieldparam [Exception] error The error raised.

@example

require "google/cloud/firestore"

firestore = Google::Cloud::Firestore.new

# Create a query
query = firestore.col(:cities).order(:population, :desc)

listener = query.listen do |snapshot|
  puts "The query snapshot has #{snapshot.docs.count} documents "
  puts "and has #{snapshot.changes.count} changes."
end

# Register to be notified when unhandled errors occur.
listener.on_error do |error|
  puts error
end

# When ready, stop the listen operation and close the stream.
listener.stop
# File lib/google/cloud/firestore/query_listener.rb, line 152
def on_error &block
  raise ArgumentError, "on_error must be called with a block" unless block_given?
  synchronize { @error_callbacks << block }
end
start() click to toggle source

@private

# File lib/google/cloud/firestore/query_listener.rb, line 63
def start
  @listener.start
  self
end
stop() click to toggle source

Stops the client listening for changes.

@example

require "google/cloud/firestore"

firestore = Google::Cloud::Firestore.new

# Create a query
query = firestore.col(:cities).order(:population, :desc)

listener = query.listen do |snapshot|
  puts "The query snapshot has #{snapshot.docs.count} documents "
  puts "and has #{snapshot.changes.count} changes."
end

# When ready, stop the listen operation and close the stream.
listener.stop
# File lib/google/cloud/firestore/query_listener.rb, line 87
def stop
  @listener.stop
end
stopped?() click to toggle source

Whether the client has stopped listening for changes.

@example

require "google/cloud/firestore"

firestore = Google::Cloud::Firestore.new

# Create a query
query = firestore.col(:cities).order(:population, :desc)

listener = query.listen do |snapshot|
  puts "The query snapshot has #{snapshot.docs.count} documents "
  puts "and has #{snapshot.changes.count} changes."
end

# Checks if the listener is stopped.
listener.stopped? #=> false

# When ready, stop the listen operation and close the stream.
listener.stop

# Checks if the listener is stopped.
listener.stopped? #=> true
# File lib/google/cloud/firestore/query_listener.rb, line 116
def stopped?
  @listener.stopped?
end