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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#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
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#
# http://www.apache.org/licenses/LICENSE-2.0
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#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
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# ++
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require 'mongo/collection'
require 'mongo/message'
require 'mongo/types/code'
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module Mongo
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# A query against a collection. A query's selector is a hash. See the
# Mongo documentation for query details.
class Query
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attr_accessor :number_to_skip, :number_to_return, :order_by, :snapshot
# If true, $explain will be set in QueryMessage that uses this query.
attr_accessor :explain
# Either +nil+ or a hash (preferably an OrderedHash).
attr_accessor :hint
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.)
#
# number_to_skip :: Number of records to skip before returning
# records. Default is 0.
#
# number_to_return :: Max number of records to return. (Called :limit
# in calls to Collection#find.) Default is 0 (all
# records).
#
# 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.)
#
# hint :: If not +nil+, specifies query hint fields. Must be either
# +nil+ or a hash (preferably an OrderedHash). See
# Collection#hint.
def initialize(sel={}, return_fields=nil, number_to_skip=0, number_to_return=0, order_by=nil, hint=nil, snapshot=nil)
@number_to_skip, @number_to_return, @order_by, @hint, @snapshot =
number_to_skip, number_to_return, order_by, hint, snapshot
@explain = nil
self.selector = sel
self.fields = return_fields
end
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# Set query selector hash. If sel is Code/string, it will be used as a
# $where clause. (See Mongo docs for details.)
def selector=(sel)
@selector = case sel
when nil
{}
when Code
{"$where" => sel}
when String
{"$where" => Code.new(sel)}
when Hash
sel
end
end
# Set fields to return. If +val+ is +nil+ or empty, all fields will be
# returned.
def fields=(val)
@fields = val
@fields = nil if @fields && @fields.empty?
end
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def fields
case @fields
when String
{@fields => 1}
when Array
if @fields.length == 0
nil
else
h = {}
@fields.each { |field| h[field] = 1 }
h
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end
else # nil, anything else
nil
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end
end
def contains_special_fields
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@order_by || @explain || @hint || @snapshot
end
def to_s
"find(#{@selector.inspect})" + (@order_by ? ".sort(#{@order_by.inspect})" : "")
end
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end
end