429 lines
14 KiB
Ruby
429 lines
14 KiB
Ruby
# --
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# Copyright (C) 2008-2009 10gen Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ++
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require 'mongo/query'
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module Mongo
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# A named collection of records in a database.
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class Collection
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attr_reader :db, :name, :hint
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def initialize(db, name)
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case name
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when Symbol, String
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else
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raise TypeError, "new_name must be a string or symbol"
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end
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name = name.to_s
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if name.empty? or name.include? ".."
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raise InvalidName, "collection names cannot be empty"
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end
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if name.include? "$" and not name.match(/^\$cmd/)
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raise InvalidName, "collection names must not contain '$'"
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end
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if name.match(/^\./) or name.match(/\.$/)
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raise InvalidName, "collection names must not start or end with '.'"
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end
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@db, @name = db, name
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@hint = nil
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end
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# Get a sub-collection of this collection by name.
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#
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# Raises InvalidName if an invalid collection name is used.
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#
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# :name :: the name of the collection to get
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def [](name)
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name = "#{self.name}.#{name}"
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return Collection.new(db, name) if !db.strict? || db.collection_names.include?(name)
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raise "Collection #{name} doesn't exist. Currently in strict mode."
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end
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# Set hint fields to use and return +self+. hint may be a single field
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# name, array of field names, or a hash (preferably an OrderedHash).
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# May be +nil+.
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def hint=(hint)
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@hint = normalize_hint_fields(hint)
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self
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end
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# Query the database.
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#
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# The +selector+ argument is a prototype document that all results must
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# match. For example:
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#
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# collection.find({"hello" => "world"})
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#
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# only matches documents that have a key "hello" with value "world".
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# Matches can have other keys *in addition* to "hello".
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#
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# If given an optional block +find+ will yield a Cursor to that block,
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# close the cursor, and then return nil. This guarantees that partially
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# evaluated cursors will be closed. If given no block +find+ returns a
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# cursor.
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#
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# :selector :: A document (hash) specifying elements which must be
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# present for a document to be included in the result set.
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#
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# Options:
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# :fields :: Array of field names that should be returned in the result
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# set ("_id" will always be included). By limiting results
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# to a certain subset of fields you can cut down on network
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# traffic and decoding time.
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# :skip :: Number of documents to omit (from the start of the result set)
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# when returning the results
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# :limit :: Maximum number of records to return
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# :sort :: An array of [key, direction] pairs to sort by. Direction should
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# be specified as Mongo::ASCENDING (or :ascending / :asc) or
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# Mongo::DESCENDING (or :descending / :desc)
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# :hint :: See #hint. This option overrides the collection-wide value.
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# :snapshot :: If true, snapshot mode will be used for this query.
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# Snapshot mode assures no duplicates are returned, or
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# objects missed, which were preset at both the start and
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# end of the query's execution. For details see
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# http://www.mongodb.org/display/DOCS/How+to+do+Snapshotting+in+the+Mongo+Database
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# :timeout :: When +true+ (default), the returned cursor will be subject to
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# the normal cursor timeout behavior of the mongod process.
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# When +false+, the returned cursor will never timeout. Note
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# that disabling timeout will only work when #find is invoked
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# with a block. This is to prevent any inadvertant failure to
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# close the cursor, as the cursor is explicitly closed when
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# block code finishes.
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def find(selector={}, options={})
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fields = options.delete(:fields)
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fields = ["_id"] if fields && fields.empty?
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skip = options.delete(:offset) || nil
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if !skip.nil?
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warn "the :offset option to find is deprecated and will be removed. please use :skip instead"
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end
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skip = options.delete(:skip) || skip || 0
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limit = options.delete(:limit) || 0
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sort = options.delete(:sort)
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hint = options.delete(:hint)
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snapshot = options.delete(:snapshot)
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if options[:timeout] == false && !block_given?
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raise ArgumentError, "Timeout can be set to false only when #find is invoked with a block."
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end
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timeout = block_given? ? (options.delete(:timeout) || true) : true
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if hint
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hint = normalize_hint_fields(hint)
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else
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hint = @hint # assumed to be normalized already
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end
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raise RuntimeError, "Unknown options [#{options.inspect}]" unless options.empty?
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cursor = @db.query(self, Query.new(selector, fields, skip, limit, sort, hint, snapshot, timeout, @db.slave_ok?))
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if block_given?
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yield cursor
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cursor.close()
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nil
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else
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cursor
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end
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end
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# Get a single object from the database.
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#
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# Raises TypeError if the argument is of an improper type. Returns a
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# single document (hash), or nil if no result is found.
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#
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# :spec_or_object_id :: a hash specifying elements which must be
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# present for a document to be included in the result set OR an
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# instance of ObjectID to be used as the value for an _id query.
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# if nil an empty spec, {}, will be used.
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# :options :: options, as passed to Collection#find
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def find_one(spec_or_object_id=nil, options={})
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spec = case spec_or_object_id
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when nil
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{}
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when ObjectID
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{:_id => spec_or_object_id}
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when Hash
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spec_or_object_id
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else
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raise TypeError, "spec_or_object_id must be an instance of ObjectID or Hash, or nil"
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end
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find(spec, options.merge(:limit => -1)).next_object
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end
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# Save a document in this collection.
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#
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# If +to_save+ already has an '_id' then an update (upsert) operation
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# is performed and any existing document with that _id is overwritten.
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# Otherwise an insert operation is performed. Returns the _id of the
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# saved document.
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#
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# :to_save :: the document (a hash) to be saved
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#
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# Options:
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# :safe :: if true, check that the save succeeded. OperationFailure
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# will be raised on an error. Checking for safety requires an extra
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# round-trip to the database
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def save(to_save, options={})
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if id = to_save[:_id] || to_save['_id']
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update({:_id => id}, to_save, :upsert => true, :safe => options.delete(:safe))
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id
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else
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insert(to_save, :safe => options.delete(:safe))
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end
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end
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# Insert a document(s) into this collection.
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#
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# "<<" is aliased to this method. Returns the _id of the inserted
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# document or a list of _ids of the inserted documents. The object(s)
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# may have been modified by the database's PK factory, if it has one.
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#
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# :doc_or_docs :: a document (as a hash) or Array of documents to be
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# inserted
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#
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# Options:
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# :safe :: if true, check that the insert succeeded. OperationFailure
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# will be raised on an error. Checking for safety requires an extra
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# round-trip to the database
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def insert(doc_or_docs, options={})
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doc_or_docs = [doc_or_docs] if !doc_or_docs.is_a?(Array)
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res = @db.insert_into_db(@name, doc_or_docs)
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if options.delete(:safe)
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error = @db.error
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if error
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raise OperationFailure, error
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end
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end
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res.size > 1 ? res : res.first
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end
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alias_method :<<, :insert
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# Remove the records that match +selector+.
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def remove(selector={})
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@db.remove_from_db(@name, selector)
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end
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# Remove all records.
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def clear
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remove({})
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end
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# Update a single document in this collection.
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#
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# :spec :: a hash specifying elements which must be present for
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# a document to be updated
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# :document :: a hash specifying the fields to be changed in the
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# selected document, or (in the case of an upsert) the document to
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# be inserted
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#
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# Options:
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# :upsert :: if true, perform an upsert operation
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# :safe :: if true, check that the update succeeded. OperationFailure
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# will be raised on an error. Checking for safety requires an extra
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# round-trip to the database
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def update(spec, document, options={})
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upsert = options.delete(:upsert)
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safe = options.delete(:safe)
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if upsert
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@db.repsert_in_db(@name, spec, document)
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else
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@db.replace_in_db(@name, spec, document)
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end
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if safe
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error = @db.error
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if error
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raise OperationFailure, error
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end
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end
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end
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# Create a new index. +field_or_spec+
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# should be either a single field name or a Array of [field name,
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# direction] pairs. Directions should be specified as
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# Mongo::ASCENDING or Mongo::DESCENDING.
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# +unique+ is an optional boolean indicating whether this index
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# should enforce a uniqueness constraint.
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def create_index(field_or_spec, unique=false)
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@db.create_index(@name, field_or_spec, unique)
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end
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# Drop index +name+.
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def drop_index(name)
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@db.drop_index(@name, name)
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end
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# Drop all indexes.
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def drop_indexes
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# just need to call drop indexes with no args; will drop them all
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@db.drop_index(@name, '*')
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end
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# Drop the entire collection. USE WITH CAUTION.
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def drop
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@db.drop_collection(@name)
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end
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# Perform a query similar to an SQL group by operation.
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#
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# Returns an array of grouped items.
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#
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# :keys :: Array of fields to group by
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# :condition :: specification of rows to be considered (as a 'find'
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# query specification)
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# :initial :: initial value of the aggregation counter object
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# :reduce :: aggregation function as a JavaScript string
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# :command :: if true, run the group as a command instead of in an
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# eval - it is likely that this option will eventually be
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# deprecated and all groups will be run as commands
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def group(keys, condition, initial, reduce, command=false)
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if command
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hash = {}
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keys.each do |k|
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hash[k] = 1
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end
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case reduce
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when Code
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else
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reduce = Code.new(reduce)
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end
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result = @db.db_command({"group" =>
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{
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"ns" => @name,
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"$reduce" => reduce,
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"key" => hash,
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"cond" => condition,
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"initial" => initial}})
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if result["ok"] == 1
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return result["retval"]
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else
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raise OperationFailure, "group command failed: #{result['errmsg']}"
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end
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end
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case reduce
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when Code
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scope = reduce.scope
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else
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scope = {}
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end
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scope.merge!({
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"ns" => @name,
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"keys" => keys,
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"condition" => condition,
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"initial" => initial })
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group_function = <<EOS
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function () {
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var c = db[ns].find(condition);
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var map = new Map();
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var reduce_function = #{reduce};
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while (c.hasNext()) {
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var obj = c.next();
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var key = {};
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for (var i = 0; i < keys.length; i++) {
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var k = keys[i];
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key[k] = obj[k];
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}
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var aggObj = map.get(key);
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if (aggObj == null) {
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var newObj = Object.extend({}, key);
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aggObj = Object.extend(newObj, initial);
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map.put(key, aggObj);
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}
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reduce_function(obj, aggObj);
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}
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return {"result": map.values()};
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}
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EOS
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return @db.eval(Code.new(group_function, scope))["result"]
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end
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# Rename this collection.
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#
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# If operating in auth mode, client must be authorized as an admin to
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# perform this operation. Raises +InvalidName+ if +new_name+ is an invalid
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# collection name.
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#
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# :new_name :: new name for this collection
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def rename(new_name)
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case new_name
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when Symbol, String
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else
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raise TypeError, "new_name must be a string or symbol"
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end
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new_name = new_name.to_s
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if new_name.empty? or new_name.include? ".."
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raise InvalidName, "collection names cannot be empty"
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end
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if new_name.include? "$"
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raise InvalidName, "collection names must not contain '$'"
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end
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if new_name.match(/^\./) or new_name.match(/\.$/)
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raise InvalidName, "collection names must not start or end with '.'"
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end
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@db.rename_collection(@name, new_name)
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end
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# Get information on the indexes for the collection +collection_name+.
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# Returns a hash where the keys are index names (as returned by
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# Collection#create_index and the values are lists of [key, direction]
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# pairs specifying the index (as passed to Collection#create_index).
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def index_information
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@db.index_information(@name)
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end
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# Return a hash containing options that apply to this collection.
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# 'create' will be the collection name. For the other possible keys
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# and values, see DB#create_collection.
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def options
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@db.collections_info(@name).next_object()['options']
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end
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# Get the number of documents in this collection.
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def count()
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find().count()
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end
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alias :size :count
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protected
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def normalize_hint_fields(hint)
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case hint
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when String
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{hint => 1}
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when Hash
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hint
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when nil
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nil
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else
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h = OrderedHash.new
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hint.to_a.each { |k| h[k] = 1 }
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h
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end
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end
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end
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end
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