Class: Medea::JasonDeferredQuery

Inherits:
Object
  • Object
show all
Defined in:
lib/medea/jasondeferredquery.rb

Direct Known Subclasses

JasonListProperty

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ JasonDeferredQuery

Returns a new instance of JasonDeferredQuery.



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# File 'lib/medea/jasondeferredquery.rb', line 8

def initialize opts={}
  self.type = opts[:class] if opts[:class]
  self.filters = opts[:filters] if opts[:filters]
  self.result_format = opts[:format] ? opts[:format] : :search
  self.time_limit = opts[:time_limit] ? opts[:time_limit] : 0
  self.state = :prefetch
  self.contents = []
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(name, *args, &block) ⇒ Object

here we will capture: members_of(object) (where object is an instance of a class that this class can be a member of) members_of_<classname>(key) find_by_<property>(value) Will return a JasonDeferredQuery for this class with the appropriate data filter set



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# File 'lib/medea/jasondeferredquery.rb', line 24

def method_missing(name, *args, &block)
  #if we are postfetch, we throw away all our cached results
  if self.state == :postfetch
    self.state = :prefetch
    self.contents = []
  end

  field = name.to_s	

  if field =~ /^members_of$/
    #use the type and key of the first arg (being a JasonObject)
    #args[0] must be a JasonObject (or child)
    raise ArgumentError, "When looking for members, you must pass a JasonObject" unless args[0].is_a? JasonObject

    self.filters[:DATA_FILTER] ||= {}
    self.filters[:DATA_FILTER]["__member_of"] ||= []
    self.filters[:DATA_FILTER]["__member_of"] << args[0].jason_key
  elsif field =~ /^find_by_(.*)$/
    #use the property name from the name variable, and the value from the first arg
    add_data_filter $1, args[0].to_s
  else
    #no method!
    super
    return
  end
  #return self, so that we can chain up query refinements
  self
end

Instance Attribute Details

#contents ⇒ Object

Returns the value of attribute contents.



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# File 'lib/medea/jasondeferredquery.rb', line 6

def contents
  @contents
end

#filters ⇒ Object

Returns the value of attribute filters.



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# File 'lib/medea/jasondeferredquery.rb', line 6

def filters
  @filters
end

#result_format ⇒ Object

Returns the value of attribute result_format.



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# File 'lib/medea/jasondeferredquery.rb', line 6

def result_format
  @result_format
end

#state ⇒ Object

Returns the value of attribute state.



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# File 'lib/medea/jasondeferredquery.rb', line 6

def state
  @state
end

#time_limit ⇒ Object

Returns the value of attribute time_limit.



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# File 'lib/medea/jasondeferredquery.rb', line 6

def time_limit
  @time_limit
end

#type ⇒ Object

Returns the value of attribute type.



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# File 'lib/medea/jasondeferredquery.rb', line 6

def type
  @type
end

Instance Method Details

#[](index) ⇒ Object

array access interface



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# File 'lib/medea/jasondeferredquery.rb', line 104

def [](index)
  execute_query unless self.state == :postfetch
  self.contents[index]
end

#add_data_filter(property, value) ⇒ Object

end query interface



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# File 'lib/medea/jasondeferredquery.rb', line 67

def add_data_filter property, value
  self.filters[:DATA_FILTER] ||= {}
  self.filters[:DATA_FILTER][property] = value
end

#count ⇒ Object 



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# File 'lib/medea/jasondeferredquery.rb', line 114

def count
  execute_query unless self.state == :postfetch
  self.contents.count
end

#each(&block) ⇒ Object 



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# File 'lib/medea/jasondeferredquery.rb', line 109

def each(&block)
  execute_query unless self.state == :postfetch
  self.contents.each &block
end

#execute_query(content = true) ⇒ Object

end array interface



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# File 'lib/medea/jasondeferredquery.rb', line 136

def execute_query content=true
  #hit the URL
  #fill self.contents with :ghost versions of JasonObjects
  
  begin
    response = RestClient.get to_url
    result = JSON.parse(response)
    self.contents = []
    #results are in a hash, their keys are just numbers
    result.keys.each do |k|
      if k =~ /^[0-9]+$/
        #this is a result! get the key
        item = type.new(result[k]["HTTP_X_KEY"], :lazy)
        if content && result[k].has_key?("CONTENT") && result[k]["CONTENT"] != ""
          item.instance_variable_set(:@__jason_data, result[k]["CONTENT"])
          item.instance_variable_set(:@__jason_state, :stale)
        end
        if result[k].has_key?("HTTP_X_PARENT") && result[k]["HTTP_X_PARENT"] != ""
          item.jason_parent_key = result[k]["HTTP_X_PARENT"]
        end
        if result[k].has_key?("TIMESTAMP")
          item.instance_variable_set :@__jason_timestamp, result[k]["TIMESTAMP"]
        end
        self.contents << item
      end
    end

    self.state = :postfetch
  rescue JSON::ParserError
    #we assume that a parser error means that there are no results, or a problem with the template
    #(currently a problem with the template is causing a parser error when there's no results)
    self.contents = []
    self.state = :postfetch
  end
  result
end

#first ⇒ Object 



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# File 'lib/medea/jasondeferredquery.rb', line 131

def first
  self[0]
end

#include?(item) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/medea/jasondeferredquery.rb', line 119

def include?(item)
  execute_query unless self.state == :postfetch
  self.contents.each do |i|
    return true if i.jason_key == item.jason_key
  end
  false
end

#last ⇒ Object 



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# File 'lib/medea/jasondeferredquery.rb', line 127

def last
  self[-1]
end

#limit(n) ⇒ Object 



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# File 'lib/medea/jasondeferredquery.rb', line 53

def limit n
  self.filters[:TOP] = n
end

#limit=(n) ⇒ Object 



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# File 'lib/medea/jasondeferredquery.rb', line 57

def limit= n
  limit n
end

#to_url ⇒ Object 



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# File 'lib/medea/jasondeferredquery.rb', line 72

def to_url
  url = "#{JasonDB::db_auth_url}@#{self.time_limit}.#{self.result_format}?"
  filter_array = []
  unsafe = Regexp.new("[^#{URI::PATTERN::UNRESERVED}]")
  self.filters.each do |name, val|
    if not val
      filter_array << URI.escape(name.to_s, unsafe)
      next
    else
      #FILTER's value is a hash (to avoid dupes)
      #DATA_FILTER's value is a hash
      if val.is_a? Hash
        #for each k/v in the hash, we want to add an entry to filter_array
        val.each do |field ,value|
          if value.is_a? Array
            value.each do |i|
              filter_array << URI.escape("#{name.to_s}=#{field}:#{i}", unsafe)
            end
          else
            filter_array << URI.escape("#{name.to_s}=#{field.to_s}:#{value.to_s}", unsafe)
          end
        end
      else
        filter_array << URI.escape("#{name.to_s}=#{val.to_s}", unsafe)
      end
    end
  end

  url + filter_array.join("&")
end

#top(n) ⇒ Object

synonym for limit



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# File 'lib/medea/jasondeferredquery.rb', line 62

def top n
  limit n
end