Class: DatastaxRails::Cql::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/datastax_rails/cql/base.rb

Overview

Base class for CQL generation

Instance Method Summary collapse

Constructor Details

#initialize(klass, *_args) ⇒ Base

Base initialize that sets the default consistency.



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# File 'lib/datastax_rails/cql/base.rb', line 6

def initialize(klass, *_args)
  @klass = klass
  @consistency = klass.default_consistency.to_s.downcase.to_sym
  @keyspace = DatastaxRails::Base.config[:keyspace]
  @values = []
end

Instance Method Details

#execute ⇒ Object

Generates the CQL and calls Cassandra to execute it. If you are using this outside of Rails, then DatastaxRails::Base.connection must have already been set up (Rails does this for you).



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# File 'lib/datastax_rails/cql/base.rb', line 26

def execute
  cql = to_cql.force_encoding('UTF-8')

  ActiveSupport::Notifications.instrument(
    'cql.datastax_rails',
    name:           'CQL',
    cql:            cql,
    klass:          @klass,
    connection_id:  DatastaxRails::Base.connection.object_id,
    statement_name: self.class.name,
    binds:          @values) do |payload|
    digest = Digest::MD5.digest cql
    try_again = true
    begin
      DatastaxRails::Base.reconnect unless DatastaxRails::Base.connection
      stmt = DatastaxRails::Base.statement_cache[digest] ||= DatastaxRails::Base.connection.prepare(cql)
      stmt = stmt.bind(@values)
      if @consistency
        results = DatastaxRails::Base.connection.execute(stmt, consistency: @consistency)
      else
        results = DatastaxRails::Base.connection.execute(stmt)
      end
      payload[:result_count] = results.respond_to?(:count) ? results.count : 'No'
      DatastaxRails::Base.current_server = results.execution_info.hosts.first.ip.to_s
      results
    rescue Cassandra::Errors::NoHostsAvailable
      if try_again
        Rails.logger.warn('Lost connection to Cassandra. Attempting to reconnect...')
        try_again = false
        DatastaxRails::Base.reconnect
        retry
      else
        raise
      end
    end
  end
end

#to_cql ⇒ Object

Abstract. Should be overridden by subclasses



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# File 'lib/datastax_rails/cql/base.rb', line 19

def to_cql
  fail NotImplementedError
end

#using(consistency) ⇒ Object 



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# File 'lib/datastax_rails/cql/base.rb', line 13

def using(consistency)
  @consistency = consistency.to_s.downcase.to_sym
  self
end