Class: XGen::Mongo::Driver::Collection

Inherits:
Object
  • Object
show all
Defined in:
lib/mongo/collection.rb

Overview

A named collection of records in a database.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(db, name) ⇒ Collection

Returns a new instance of Collection.



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# File 'lib/mongo/collection.rb', line 28

def initialize(db, name)
  @db, @name = db, name
  @hint = nil
end

Instance Attribute Details

#db ⇒ Object (readonly)

Returns the value of attribute db.



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# File 'lib/mongo/collection.rb', line 26

def db
  @db
end

#hint ⇒ Object

Returns the value of attribute hint.



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# File 'lib/mongo/collection.rb', line 26

def hint
  @hint
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/mongo/collection.rb', line 26

def name
  @name
end

Instance Method Details

#clear ⇒ Object

Remove all records.



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# File 'lib/mongo/collection.rb', line 102

def clear
  remove({})
end

#count(selector = {}) ⇒ Object

Return the number of records that match selector. If selector is nil or an empty hash, returns the count of all records.



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# File 'lib/mongo/collection.rb', line 211

def count(selector={})
  @db.count(@name, selector || {})
end

#create_index(field_or_spec, unique = false) ⇒ Object

Create a new index. field_or_spec should be either a single field name or a Array of [field name, direction] pairs. Directions should be specified as XGen::Mongo::ASCENDING or XGen::Mongo::DESCENDING. unique is an optional boolean indicating whether this index should enforce a uniqueness constraint.



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# File 'lib/mongo/collection.rb', line 131

def create_index(field_or_spec, unique=false)
  @db.create_index(@name, field_or_spec, unique)
end

#drop ⇒ Object

Drop the entire collection. USE WITH CAUTION.



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# File 'lib/mongo/collection.rb', line 147

def drop
  @db.drop_collection(@name)
end

#drop_index(name) ⇒ Object

Drop index name.



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# File 'lib/mongo/collection.rb', line 136

def drop_index(name)
  @db.drop_index(@name, name)
end

#drop_indexes ⇒ Object

Drop all indexes.



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# File 'lib/mongo/collection.rb', line 141

def drop_indexes
  # just need to call drop indexes with no args; will drop them all
  @db.drop_index(@name, '*')
end

#find(selector = {}, options = {}) ⇒ Object

Return records that match a selector hash. See Mongo docs for details.

Options:

:fields

Array of collection field names; only those will be returned (plus _id if defined)

:offset

Start at this record when returning records

:limit

Maximum number of records to return

:sort

Either hash of field names as keys and 1/-1 as values; 1 == ascending, -1 == descending, or array of field names (all assumed to be sorted in ascending order).

:hint

See #hint. This option overrides the collection-wide value.

Raises:

  • (RuntimeError) 


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# File 'lib/mongo/collection.rb', line 52

def find(selector={}, options={})
  fields = options.delete(:fields)
  fields = nil if fields && fields.empty?
  offset = options.delete(:offset) || 0
  limit = options.delete(:limit) || 0
  sort = options.delete(:sort)
  hint = options.delete(:hint)
  if hint
    hint = normalize_hint_fields(hint)
  else
    hint = @hint        # assumed to be normalized already
  end
  raise RuntimeError, "Unknown options [#{options.inspect}]" unless options.empty?
  @db.query(self, Query.new(selector, fields, offset, limit, sort, hint))
end

#find_first(selector = {}, options = {}) ⇒ Object

Find the first record that matches selector. See #find.



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# File 'lib/mongo/collection.rb', line 69

def find_first(selector={}, options={})
  h = options.dup
  h[:limit] = 1
  cursor = find(selector, h)
  cursor.next_object    # don't need to explicitly close b/c of limit
end

#group(keys, condition, initial, reduce) ⇒ Object

Perform a query similar to an SQL group by operation.

Returns an array of grouped items.

:keys

list of fields to group by

:condition

specification of rows to be considered (as a ‘find’ query specification)

:initial

initial value of the aggregation counter object

:reduce

aggregation function as a JavaScript string



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# File 'lib/mongo/collection.rb', line 160

def group(keys, condition, initial, reduce)
  group_function = <<EOS
function () {
    var c = db[ns].find(condition);
    var map = new Map();
    var reduce_function = #{reduce};
    while (c.hasNext()) {
var obj = c.next();

var key = {};
for (var i in keys) {
    key[keys[i]] = obj[keys[i]];
}

var aggObj = map.get(key);
if (aggObj == null) {
    var newObj = Object.extend({}, key);
    aggObj = Object.extend(newObj, initial);
    map.put(key, aggObj);
}
reduce_function(obj, aggObj);
    }
    return {"result": map.values()};
}
EOS
  return @db.eval(Code.new(group_function,
                           {
                             "ns" => @name,
                             "keys" => keys,
                             "condition" => condition,
                             "initial" => initial
                           }))["result"]
end

#index_information ⇒ Object

Get information on the indexes for the collection collection_name. Returns a hash where the keys are index names (as returned by Collection#create_index and the values are lists of [key, direction] pairs specifying the index (as passed to Collection#create_index).



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# File 'lib/mongo/collection.rb', line 198

def index_information
  @db.index_information(@name)
end

#insert(*objects) ⇒ Object Also known as: <<

Insert objects, which are hashes. “<<” is aliased to this method. Returns either the single inserted object or a new array containing objects. The object(s) may have been modified by the database’s PK factory, if it has one.



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# File 'lib/mongo/collection.rb', line 89

def insert(*objects)
  objects = objects.first if objects.size == 1 && objects.first.is_a?(Array)
  res = @db.insert_into_db(@name, objects)
  res.size > 1 ? res : res.first
end

#modify(selector, modifier_obj) ⇒ Object

Update records that match selector by applying obj as an update. Both selector and modifier_obj are required.



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# File 'lib/mongo/collection.rb', line 119

def modify(selector, modifier_obj)
  raise "no object" unless modifier_obj
  raise "no selector" unless selector
  @db.modify_in_db(@name, selector, modifier_obj)
end

#options ⇒ Object

Return a hash containing options that apply to this collection. ‘create’ will be the collection name. For the other possible keys and values, see DB#create_collection.



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# File 'lib/mongo/collection.rb', line 205

def options
  @db.collections_info(@name).next_object()['options']
end

#remove(selector = {}) ⇒ Object

Remove the records that match selector.



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# File 'lib/mongo/collection.rb', line 97

def remove(selector={})
  @db.remove_from_db(@name, selector)
end

#replace(selector, obj) ⇒ Object

Update records that match selector by applying obj as an update.



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# File 'lib/mongo/collection.rb', line 113

def replace(selector, obj)
  @db.replace_in_db(@name, selector, obj)
end

#repsert(selector, obj) ⇒ Object

Update records that match selector by applying obj as an update. If no match, inserts (???).



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# File 'lib/mongo/collection.rb', line 108

def repsert(selector, obj)
  @db.repsert_in_db(@name, selector, obj)
end

#save(object) ⇒ Object

Save an updated object to the collection, or insert it if it doesn’t exist already.



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# File 'lib/mongo/collection.rb', line 77

def save(object)
  if id = object[:_id] || object['_id']
    repsert({:_id => id}, object)
  else
    insert(object)
  end
end