Exception: Promiscuous::Error::Dependency

Inherits:
Base
  • Object
show all
Defined in:
lib/promiscuous/error/dependency.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Dependency

Returns a new instance of Dependency.



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# File 'lib/promiscuous/error/dependency.rb', line 4

def initialize(options={})
  self.operation = options[:operation]
end

Instance Attribute Details

#dependency_solutions ⇒ Object

Returns the value of attribute dependency_solutions.



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# File 'lib/promiscuous/error/dependency.rb', line 2

def dependency_solutions
  @dependency_solutions
end

#operation ⇒ Object

Returns the value of attribute operation.



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# File 'lib/promiscuous/error/dependency.rb', line 2

def operation
  @operation
end

Class Method Details

.explain_operation(operation, limit = 100) ⇒ Object 



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# File 'lib/promiscuous/error/dependency.rb', line 78

def self.explain_operation(operation, limit=100)
  instance = operation.instance
  selector   = instance ? get_selector(instance.attributes, limit) : ""
  class_name = instance ? instance.class : "Unknown"

  if operation.operation == :create
    "#{instance.class}.create(#{selector})"
  else
    case operation.operation_ext || operation.operation
    when :count     then verb = 'count'
    when :mapreduce then verb = 'mapreduce(...)'
    when :read      then verb = operation.multi? ? 'each { ... }' : 'first'
    when :update    then verb = operation.multi? ? 'update_all'   : 'update'
    when :destroy   then verb = operation.multi? ? 'delete_all'   : 'delete'
    end
    msg = "#{class_name}#{selector.present? ? ".where(#{selector})" : ""}.#{verb}"
    if operation.operation == :update && operation.respond_to?(:change) && operation.change
      msg += "(#{get_selector(operation.change, limit)})"
    end

    if operation.operation == :commit
      msg = "Transaction commit"
    end

    msg
  end
end

.get_selector(attributes, limit = 100) ⇒ Object 



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# File 'lib/promiscuous/error/dependency.rb', line 106

def self.get_selector(attributes, limit=100)
  # TODO ActiveRecord?
  attributes = attributes['$set'] if attributes.count == 1 && attributes['$set']
  attributes.reject! { |k,v| v.nil? }
  selector = attributes.map { |k,v| ":#{k} => #{v}" }.join(", ")
  selector = "#{selector[0...(limit-3)]}..." if selector.size > limit
  selector
end

Instance Method Details

#message ⇒ Object Also known as: to_s

TODO Convert all that with Erb



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# File 'lib/promiscuous/error/dependency.rb', line 10

def message
  msg = nil
  case operation.operation
  when :read
    msg =  "Promiscuous doesn't have any tracked dependencies to perform this multi read operation.\n" +
           "This is what you can do:\n\n" +
           "  1. Bypass Promiscuous\n\n" +
           "     If you don't use the result of this operation in your following writes,\n" +
           "     you can wrap your read query in a 'without_promiscuous { }' block.\n" +
           "     This is the preferred solution when you are sure that the read doesn't\n" +
           "     influence the value of a published attribute.\n\n" +
           "     Rule of thumb: Predicates (methods ending with ?) are often suitable for this use case.\n\n"
    cnt = 2
    if operation.operation_ext != :count
      msg += "  #{cnt}. Synchronize on individual instances\n\n" +
             "     If the collection you are iterating through is small (<10), it becomes intersting\n" +
             "     to track instances through their ids instead of the query selector. Example:\n\n" +
             "          criteria.without_promiscuous.each do |doc|\n" +
             "            next if doc.should_do_something?\n" +
             "            doc.reload # tell promiscuous to track the instance\n" +
             "            doc.do_something!\n" +
             "          end\n\n"
      cnt += 1
    end
    if operation.selector_keys.present?
      msg += "  #{cnt}. Track New Dependencies\n\n" +
             "     Add #{operation.selector_keys.count == 1 ? "the following line" : "one of the following lines"} " +
                  "in the #{operation.instance.class} model:\n\n" +
             "       class #{operation.instance.class}\n" +
                  operation.selector_keys.map { |field| "         track_dependencies_of :#{field}" }.join("\n") + "\n" +
             "       end\n\n" +
             (operation.selector_keys.count > 1 ?
             "     The more specific field, the better. Promiscuous works better when working with small subsets\n" +
             "     For example, tracking something like 'member_id' is a fairly safe choice.\n\n" : "") +
             "     Note that dependency tracking slows down your writes. It can be seen as the analogous\n" +
             "     of an index on a regular database.\n" +
             "     You may find more information about the implications in the Promiscuous wiki (TODO:link).\n\n"
    end
  when :update
    msg = "Promiscuous cannot track dependencies of a multi update operation.\n" +
           "This is what you can do:\n\n" +
           "  1. Instead of doing a multi updates, update each instance separately\n\n" +
           "  2. Do not assign has_many associations directly, but use the << operator instead.\n\n"
  when :destroy
    msg = "Promiscuous cannot track dependencies of a multi delete operation.\n" +
           "This is what you can do:\n\n" +
          "   1. Instead of doing a multi delete, delete each instance separatly.\n\n" +
          "   2. Use destroy_all instead of destroy_all.\n\n" +
          "   3. Declare your has_many relationships with :dependent => :destroy instead of :delete.\n\n"
  end

  msg += "#{"-" * 100}\n\n"

  msg += "Promiscuous cannot allow the following "
  case operation.operation_ext || operation.operation
  when :count     then msg += 'count'
  when :mapreduce then msg += 'mapreduce'
  when :read      then msg += 'each loop'
  when :update    then msg += 'multi update'
  when :destroy   then msg += 'multi destroy'
  end
  msg += "  #{self.class.explain_operation(self.operation)}"
  msg += "\n\nProTip: Try again with TRACE=2 in the shell or ENV['TRACE']='2' in the console.\n" unless ENV['TRACE']
  msg
rescue Exception => e
  "#{e}\n#{e.backtrace.join("\n")}"
end