class Neo4j::Index::LuceneQuery

LuceneQuery

This object is returned when you call the find method on the Node, Relationship. The actual query is not executed until the first item is requested.

You can perform a query in many different ways:

By Hash

Example:

Person.find(:name => 'foo', :age => 3)

By Range

Example:

Person.find(:age).between(15,35)

By Lucene Query Syntax

Example

Car.find('wheels:"4" AND colour: "blue")

For more information about the syntax see lucene.apache.org/java/3_0_2/queryparsersyntax.html

By Compound Queries

You can combine several queries by ANDing those together.

Example:

Vehicle.find(:weight).between(5.0, 100000.0).and(:name).between('a', 'd')

See Also

Attributes

left_and_query[RW]
left_or_query[RW]
right_not_query[RW]

Public Class Methods

new(index, decl_props, query, params={}) click to toggle source 
# File lib/neo4j/index/lucene_query.rb, line 43
def initialize(index, decl_props, query, params={})
  @index      = index
  @query      = query
  @decl_props = decl_props
  @params     = params

  if params.include?(:sort)
    @order = {}
    params[:sort].each_pair { |k, v| @order[k] = (v == :desc) }
  end
end

Public Instance Methods

[](index) click to toggle source

returns the n’th search item Does simply loop all search items till the n’th is found.

# File lib/neo4j/index/lucene_query.rb, line 102
def [](index)
  i = 0
  each{|x| return x if i == index; i += 1}
  nil # out of index
end
and(query2) click to toggle source

Create a compound lucene query.

Parameters

query2

the query that should be AND together

Example

Person.find(:name=>'kalle').and(:age => 3)

# File lib/neo4j/index/lucene_query.rb, line 158
def and(query2)
  LuceneQuery.new(@index, @decl_props, query2).tap { |new_query| new_query.left_and_query = self }
end
asc(*fields) click to toggle source

Sort ascending the given fields.

# File lib/neo4j/index/lucene_query.rb, line 196
def asc(*fields)
  @order = fields.inject(@order || {}) { |memo, field| memo[field] = false; memo }
  self
end
between(lower, upper, lower_incusive=false, upper_inclusive=false) click to toggle source

Performs a range query Notice that if you don’t specify a type when declaring a property a String range query will be performed.

# File lib/neo4j/index/lucene_query.rb, line 121
def between(lower, upper, lower_incusive=false, upper_inclusive=false)
  raise "Expected a symbol. Syntax for range queries example: index(:weight).between(a,b)" unless Symbol === @query
  raise "Can't only do range queries on Neo4j::NodeMixin, Neo4j::Model, Neo4j::RelationshipMixin" unless @decl_props
  # check that we perform a range query on the same values as we have declared with the property :key, :type => ...
  type = @decl_props[@query] && @decl_props[@query][:type]
  raise "find(#{@query}).between(#{lower}, #{upper}): #{lower} not a #{type}" if type && !type === lower.class
  raise "find(#{@query}).between(#{lower}, #{upper}): #{upper} not a #{type}" if type && !type === upper.class

  # Make it possible to convert those values
  @query = range_query(@query, lower, upper, lower_incusive, upper_inclusive)
  self
end
close() click to toggle source

Close hits

Closes the underlying search result. This method should be called whenever you’ve got what you wanted from the result and won’t use it anymore. It’s necessary to call it so that underlying indexes can dispose of allocated resources for this search result. You can however skip to call this method if you loop through the whole result, then close() will be called automatically. Even if you loop through the entire result and then call this method it will silently ignore any consequtive call (for convenience).

This must be done according to the Neo4j Java Documentation:

# File lib/neo4j/index/lucene_query.rb, line 89
def close
  @hits.close if @hits
  @hits = nil
end
desc(*fields) click to toggle source

Sort descending the given fields.

# File lib/neo4j/index/lucene_query.rb, line 190
def desc(*fields)
  @order = fields.inject(@order || {}) { |memo, field| memo[field] = true; memo }
  self
end
each() { |wrapper| ... } click to toggle source

Since we include the Ruby Enumerable mixin we need this method.

# File lib/neo4j/index/lucene_query.rb, line 63
def each
  if @params.include?(:per_page)
    # paginate the result, used by the will_paginate gem
    page     = @params[:page] || 1
    per_page = @params[:per_page]
    to       = per_page * page
    from     = to - per_page
    i        = 0
    hits.each do |node|
      yield node.wrapper if i >= from
      i += 1
      break if i >= to
    end
  else
    hits.each { |n| yield n.wrapper }
  end
end
empty?() click to toggle source

True if there is no search hits.

# File lib/neo4j/index/lucene_query.rb, line 95
def empty?
  hits.size == 0
end
not(query2) click to toggle source

Create a NOT lucene query.

Parameters

query2

the query that should exclude matching results

Example

Person.find(:age => 3).not(:name=>'kalle')

# File lib/neo4j/index/lucene_query.rb, line 184
def not(query2)
  LuceneQuery.new(@index, @decl_props, query2).tap { |new_query| new_query.right_not_query = self }
end
or(query2) click to toggle source

Create an OR lucene query.

Parameters

query2

the query that should be OR together

Example

Person.find(:name=>'kalle').or(:age => 3)

# File lib/neo4j/index/lucene_query.rb, line 171
def or(query2)
  LuceneQuery.new(@index, @decl_props, query2).tap { |new_query| new_query.left_or_query = self }
end
range_query(field, lower, upper, lower_incusive, upper_inclusive) click to toggle source 
# File lib/neo4j/index/lucene_query.rb, line 134
def range_query(field, lower, upper, lower_incusive, upper_inclusive)
  lower = TypeConverters.convert(lower)
  upper = TypeConverters.convert(upper)

  case lower
    when Fixnum
      org.apache.lucene.search.NumericRangeQuery.new_long_range(field.to_s, lower, upper, lower_incusive, upper_inclusive)
    when Float
      org.apache.lucene.search.NumericRangeQuery.new_double_range(field.to_s, lower, upper, lower_incusive, upper_inclusive)
    else
      org.apache.lucene.search.TermRangeQuery.new(field.to_s, lower, upper, lower_incusive, upper_inclusive)
  end
end
size() click to toggle source

Returns the number of search hits

# File lib/neo4j/index/lucene_query.rb, line 109
def size
  hits.size
end