Class: OAI::Provider::ResumptionToken

Inherits:
Object
  • Object
show all
Defined in:
lib/oai/provider/resumption_token.rb

Overview

OAI::Provider::ResumptionToken

The ResumptionToken class forms the basis of paging query results. It provides several helper methods for dealing with resumption tokens.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(last_id, options, expiration = nil, total = nil) ⇒ ResumptionToken

Returns a new instance of ResumptionToken.



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# File 'lib/oai/provider/resumption_token.rb', line 51

def initialize(last_id, options, expiration = nil, total = nil)
  @prefix = options[:metadata_prefix]
  @set = options[:set]
  @last = options[:last]
  @from = options[:from] if options[:from]
  @until = options[:until] if options[:until]
  @expiration = expiration if expiration
  @total = total if total
  @last_id = last_id
end

Instance Attribute Details

#expiration ⇒ Object (readonly)

Returns the value of attribute expiration.



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# File 'lib/oai/provider/resumption_token.rb', line 12

def expiration
  @expiration
end

#from ⇒ Object (readonly)

Returns the value of attribute from.



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# File 'lib/oai/provider/resumption_token.rb', line 12

def from
  @from
end

#last ⇒ Object (readonly)

Returns the value of attribute last.



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# File 'lib/oai/provider/resumption_token.rb', line 12

def last
  @last
end

#last_id ⇒ Object (readonly)

Returns the value of attribute last_id.



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# File 'lib/oai/provider/resumption_token.rb', line 12

def last_id
  @last_id
end

#prefix ⇒ Object (readonly)

Returns the value of attribute prefix.



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# File 'lib/oai/provider/resumption_token.rb', line 12

def prefix
  @prefix
end

#set ⇒ Object (readonly)

Returns the value of attribute set.



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# File 'lib/oai/provider/resumption_token.rb', line 12

def set
  @set
end

#total ⇒ Object

Returns the value of attribute total.



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# File 'lib/oai/provider/resumption_token.rb', line 13

def total
  @total
end

#until ⇒ Object (readonly)

Returns the value of attribute until.



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# File 'lib/oai/provider/resumption_token.rb', line 12

def until
  @until
end

Class Method Details

.extract_format(token_string) ⇒ Object

extracts the metadata prefix from a token string



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# File 'lib/oai/provider/resumption_token.rb', line 47

def self.extract_format(token_string)
  return token_string.split('.')[0]
end

.parse(token_string) ⇒ Object

parses a token string and returns a ResumptionToken



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# File 'lib/oai/provider/resumption_token.rb', line 16

def self.parse(token_string)
  begin
    options = {}
    matches = /(.+):(\d+)$/.match(token_string)
    options[:last] = matches.captures[1].to_i
    last_id = nil
    total = nil
    
    parts = matches.captures[0].split('.')
    options[:metadata_prefix] = parts.shift
    parts.each do |part|
      case part
      when /^s/
        options[:set] = part.sub(/^s\(/, '').sub(/\)$/, '')
      when /^f/
        options[:from] = Time.parse(part.sub(/^f\(/, '').sub(/\)$/, ''))
      when /^u/
        options[:until] = Time.parse(part.sub(/^u\(/, '').sub(/\)$/, ''))
      when /^l/
        last_id = part.sub(/^l\(/, '').sub(/\)$/, '')
      when /^t/
        total = part.sub(/^t\(/, '').sub(/\)$/, '')
      end
    end
    self.new(last_id, options, nil, total)
  rescue => err
    raise ResumptionTokenException.new
  end
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/oai/provider/resumption_token.rb', line 68

def ==(other)
  prefix == other.prefix and set == other.set and from == other.from and
    self.until == other.until and last == other.last and 
    expiration == other.expiration and total == other.total
end

#next(last) ⇒ Object

convenience method for setting the offset of the next set of results



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# File 'lib/oai/provider/resumption_token.rb', line 63

def next(last)
  @last = last
  self
end

#to_conditions_hash ⇒ Object

return a hash containing just the model selection parameters



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# File 'lib/oai/provider/resumption_token.rb', line 88

def to_conditions_hash
  conditions = {:metadata_prefix => self.prefix }
  conditions[:set] = self.set if self.set
  conditions[:from] = self.from if self.from
  conditions[:until] = self.until if self.until
  conditions
end

#to_s ⇒ Object

return the a string representation of the token minus the offset



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# File 'lib/oai/provider/resumption_token.rb', line 97

def to_s
  encode_conditions.gsub(/:\w+?$/, '')
end

#to_xml ⇒ Object

output an xml resumption token



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# File 'lib/oai/provider/resumption_token.rb', line 75

def to_xml
  xml = Builder::XmlMarkup.new
  token_content = if(last_id.to_s == last.to_s)
    [] # Empty token required on last page of results
  else
    [encode_conditions, hash_of_attributes]
  end
  
  xml.resumptionToken(*token_content)
  xml.target!
end