mongo-ruby-driver/lib/mongo/query.rb

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# --
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# Copyright (C) 2008-2009 10gen Inc.
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#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License, version 3, as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License
# for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
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# ++
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require 'socket'
require 'mongo/collection'
require 'mongo/message'
module XGen
module Mongo
module Driver
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# A query against a collection. A query's selector is a hash. See the
# Mongo documentation for query details.
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class Query
attr_accessor :number_to_skip, :number_to_return, :order_by
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# If true, $explain will be set in QueryMessage that uses this query.
attr_accessor :explain
# Either +nil+ or an array of hint field names.
attr_accessor :hint_fields
attr_reader :selector # writer defined below
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# sel :: A hash describing the query. See the Mongo docs for details.
#
# return_fields :: If not +nil+, a single field name or an array of
# field names. Only those fields will be returned.
# (Called :fields in calls to Collection#find.)
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#
# number_to_skip :: Number of records to skip before returning
# records. (Called :offset in calls to
# Collection#find.) Default is 0.
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#
# number_to_return :: Max number of records to return. (Called :limit
# in calls to Collection#find.) Default is 0 (all
# records).
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#
# order_by :: If not +nil+, specifies record sort order. May be a
# String, Hash, OrderedHash, or Array. If a string, the
# results will be ordered by that field in ascending
# order. If an array, it should be an array of field names
# which will all be sorted in ascending order. If a hash,
# it may be either a regular Hash or an OrderedHash. The
# keys should be field names, and the values should be 1
# (ascending) or -1 (descending). Note that if it is a
# regular Hash then sorting by more than one field
# probably will not be what you intend because key order
# is not preserved. (order_by is called :sort in calls to
# Collection#find.)
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def initialize(sel={}, return_fields=nil, number_to_skip=0, number_to_return=0, order_by=nil)
@number_to_skip, @number_to_return, @order_by = number_to_skip, number_to_return, order_by
self.selector = sel
self.fields = return_fields
end
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# Set query selector hash. If sel is a string, it will be used as a
# $where clause. (See Mongo docs for details.)
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def selector=(sel)
@selector = case sel
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when nil
{}
when String
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{"$where" => sel}
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when Hash
sel
end
end
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# Set fields to return. If +val+ is +nil+ or empty, all fields will be
# returned.
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def fields=(val)
@fields = val
@fields = nil if @fields && @fields.empty?
end
def fields
case @fields
when String
{@fields => 1}
when Array
if @fields.length == 0
nil
else
h = {}
@fields.each { |field| h[field] = 1 }
h
end
else # nil, anything else
nil
end
end
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def contains_special_fields
(@order_by != nil && @order_by.length > 0) || @explain || @hint_fields
end
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end
end
end
end