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module Mongo
module GridExt
module InstanceMethods
# Check the existence of a file matching the given query selector.
#
# Note that this method can be used with both the Grid and GridFileSystem classes. Also
# keep in mind that if you're going to be performing lots of existence checks, you should
# keep an instance of Grid or GridFileSystem handy rather than instantiating for each existence
# check. Alternatively, simply keep a reference to the proper files collection and query that
# as needed. That's exactly how this methods works.
#
# @param [Hash] selector a query selector.
#
# @example
#
# # Check for the existence of a given filename
# @grid = Mongo::GridFileSystem.new(@db)
# @grid.exist?(:filename => 'foo.txt')
#
# # Check for existence filename and content type
# @grid = Mongo::GridFileSystem.new(@db)
# @grid.exist?(:filename => 'foo.txt', :content_type => 'image/jpg')
#
# # Check for existence by _id
# @grid = Mongo::Grid.new(@db)
# @grid.exist?(:_id => BSON::ObjectId.from_string('4bddcd24beffd95a7db9b8c8'))
#
# # Check for existence by an arbitrary attribute.
# @grid = Mongo::Grid.new(@db)
# @grid.exist?(:tags => {'$in' => ['nature', 'zen', 'photography']})
#
# @return [nil, Hash] either nil for the file's metadata as a hash.
def exist?(selector)
@files.find_one(selector)
end
end
end
end
Version data entries
7 entries across 7 versions & 1 rubygems