Class: Dynamoid::Criteria::Chain

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/dynamoid/criteria/chain.rb

Overview

The criteria chain is equivalent to an ActiveRecord relation (and realistically I should change the name from chain to relation). It is a chainable object that builds up a query and eventually executes it either on an index or by a full table scan.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(source) ⇒ Chain

Create a new criteria chain.

Parameters:

  • source (Class) —

    the class upon which the ultimate query will be performed.



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# File 'lib/dynamoid/criteria/chain.rb', line 15

def initialize(source)
  @query = {}
  @source = source
  @consistent_read = false
  @scan_index_forward = true
end

Instance Attribute Details

#consistent_read ⇒ Object

Returns the value of attribute consistent_read.



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# File 'lib/dynamoid/criteria/chain.rb', line 9

def consistent_read
  @consistent_read
end

#index=(value) ⇒ Object

Sets the attribute index

Parameters:

  • value —

    the value to set the attribute index to.



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# File 'lib/dynamoid/criteria/chain.rb', line 9

def index=(value)
  @index = value
end

#limit(limit) ⇒ Object

Returns the value of attribute limit.



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# File 'lib/dynamoid/criteria/chain.rb', line 9

def limit
  @limit
end

#query ⇒ Object

Returns the value of attribute query.



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# File 'lib/dynamoid/criteria/chain.rb', line 9

def query
  @query
end

#source ⇒ Object

Returns the value of attribute source.



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# File 'lib/dynamoid/criteria/chain.rb', line 9

def source
  @source
end

#start(start) ⇒ Object

Returns the value of attribute start.



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# File 'lib/dynamoid/criteria/chain.rb', line 9

def start
  @start
end

#values ⇒ Object

Returns the value of attribute values.



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# File 'lib/dynamoid/criteria/chain.rb', line 9

def values
  @values
end

Instance Method Details

#all ⇒ Object

Returns all the records matching the criteria.

Since:

  • 0.2.0



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# File 'lib/dynamoid/criteria/chain.rb', line 46

def all
  records
end

#consistent ⇒ Object 



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# File 'lib/dynamoid/criteria/chain.rb', line 38

def consistent
  @consistent_read = true
  self
end

#consistent_opts ⇒ Object 



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# File 'lib/dynamoid/criteria/chain.rb', line 136

def consistent_opts
  { :consistent_read => consistent_read }
end

#destroy_all ⇒ Object

Destroys all the records matching the criteria.



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# File 'lib/dynamoid/criteria/chain.rb', line 52

def destroy_all
  ids = []
  
  if range?
    ranges = []
    Dynamoid::Adapter.query(source.table_name, range_query).collect do |hash| 
      ids << hash[source.hash_key.to_sym]
      ranges << hash[source.range_key.to_sym]
    end
    
    Dynamoid::Adapter.delete(source.table_name, ids,{:range_key => ranges})
  elsif index
    #TODO: test this throughly and find a way to delete all index table records for one source record
    if index.range_key?
      results = Dynamoid::Adapter.query(index.table_name, index_query.merge(consistent_opts))
    else
      results = Dynamoid::Adapter.read(index.table_name, index_query[:hash_value], consistent_opts)
    end
    
    results.collect do |hash| 
      ids << hash[source.hash_key.to_sym]
      index_ranges << hash[source.range_key.to_sym]
    end
  
    unless ids.nil? || ids.empty?
      ids = ids.to_a
  
      if @start
        ids = ids.drop_while { |id| id != @start.hash_key }.drop(1)
        index_ranges = index_ranges.drop_while { |range| range != @start.hash_key }.drop(1) unless index_ranges.nil?
      end
  
      if @limit           
        ids = ids.take(@limit) 
        index_ranges = index_ranges.take(@limit)
      end
      
      Dynamoid::Adapter.delete(source.table_name, ids)
      
      if index.range_key?
        Dynamoid::Adapter.delete(index.table_name, ids,{:range_key => index_ranges})
      else
        Dynamoid::Adapter.delete(index.table_name, ids)
      end
      
    end
  else
    Dynamoid::Adapter.scan(source.table_name, query, scan_opts).collect do |hash| 
      ids << hash[source.hash_key.to_sym]
    end
    
    Dynamoid::Adapter.delete(source.table_name, ids)
  end   
end

#each(&block) ⇒ Object

Allows you to use the results of a search as an enumerable over the results found.

Since:

  • 0.2.0



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# File 'lib/dynamoid/criteria/chain.rb', line 132

def each(&block)
  records.each(&block)
end

#first ⇒ Object

Returns the first record matching the criteria.

Since:

  • 0.2.0



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# File 'lib/dynamoid/criteria/chain.rb', line 110

def first
  limit(1).first
end

#scan_index_forward(scan_index_forward) ⇒ Object 



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# File 'lib/dynamoid/criteria/chain.rb', line 124

def scan_index_forward(scan_index_forward)
  @scan_index_forward = scan_index_forward
  self
end

#where(args) ⇒ Object

The workhorse method of the criteria chain. Each key in the passed in hash will become another criteria that the ultimate query must match. A key can either be a symbol or a string, and should be an attribute name or an attribute name with a range operator.

Examples:

A simple criteria

where(:name => 'Josh')

A more complicated criteria

where(:name => 'Josh', 'created_at.gt' => DateTime.now - 1.day)

Since:

  • 0.2.0



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# File 'lib/dynamoid/criteria/chain.rb', line 33

def where(args)
  args.each {|k, v| query[k] = v}
  self
end