Class: MongoDoc::Contexts::Mongo

Inherits:
Object
  • Object
show all
Includes:
Mongoid::Contexts::Ids, Mongoid::Contexts::Paging
Defined in:
lib/mongo_doc/contexts/mongo.rb

Constant Summary collapse

AGGREGATE_REDUCE = 
"function(obj, prev) { prev.count++; }"
GROUP_REDUCE = 
"function(obj, prev) { prev.group.push(obj); }"
MAX_REDUCE = 
"function(obj, prev) { if (prev.max == 'start') { prev.max = obj.[field]; } " +
"if (prev.max < obj.[field]) { prev.max = obj.[field]; } }"
MIN_REDUCE = 
"function(obj, prev) { if (prev.min == 'start') { prev.min = obj.[field]; } " +
"if (prev.min > obj.[field]) { prev.min = obj.[field]; } }"
SUM_REDUCE = 
"function(obj, prev) { if (prev.sum == 'start') { prev.sum = 0; } prev.sum += obj.[field]; }"

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Mongoid::Contexts::Ids

#id_criteria

Methods included from Mongoid::Contexts::Paging

#page, #paginate, #per_page

Constructor Details

#initialize(criteria) ⇒ Mongo

Create the new mongo context. This will execute the queries given the selector and options against the database.

Example:

Mongoid::Contexts::Mongo.new(criteria)



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# File 'lib/mongo_doc/contexts/mongo.rb', line 133

def initialize(criteria)
  @criteria = criteria
end

Instance Attribute Details

#cache ⇒ Object (readonly)

Returns the value of attribute cache.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 7

def cache
  @cache
end

#criteria ⇒ Object (readonly)

Returns the value of attribute criteria.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 7

def criteria
  @criteria
end

Instance Method Details

#aggregate ⇒ Object

Aggregate the context. This will take the internally built selector and options and pass them on to the Ruby driver’s group() method on the collection. The collection itself will be retrieved from the class provided, and once the query has returned it will provided a grouping of keys with counts.

Example:

context.aggregate

Returns:

A Hash with field values as keys, counts as values



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# File 'lib/mongo_doc/contexts/mongo.rb', line 25

def aggregate
  collection.group(options[:fields], selector, { :count => 0 }, AGGREGATE_REDUCE, true)
end

#avg(field) ⇒ Object

Get the average value for the supplied field.

This will take the internally built selector and options and pass them on to the Ruby driver’s group() method on the collection. The collection itself will be retrieved from the class provided, and once the query has returned it will provided a grouping of keys with averages.

Example:

context.avg(:age)

Returns:

A numeric value that is the average.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 43

def avg(field)
  total = sum(field)
  total ? (total / count) : nil
end

#count ⇒ Object

Get the count of matching documents in the database for the context.

Example:

context.count

Returns:

An Integer count of documents.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 57

def count
  @count ||= collection.find(selector, options).count
end

#distinct(field) ⇒ Object

Gets an array of distinct values for the supplied field across the entire collection or the susbset given the criteria.

Example:

context.distinct(:title)



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# File 'lib/mongo_doc/contexts/mongo.rb', line 67

def distinct(field)
  collection.distinct(field, selector)
end

#empty? ⇒ Boolean Also known as: blank?

Determine if the context is empty or blank given the criteria. Will perform a quick find_one asking only for the id.

Example:

context.blank?

Returns:



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# File 'lib/mongo_doc/contexts/mongo.rb', line 77

def empty?
  collection.find_one(selector, options).nil?
end

#execute(paginating = false) ⇒ Object

Execute the context. This will take the selector and options and pass them on to the Ruby driver’s find() method on the collection. The collection itself will be retrieved from the class provided, and once the query has returned new documents of the type of class provided will be instantiated.

Example:

mongo.execute

Returns:

An enumerable Cursor.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 94

def execute(paginating = false)
  cursor = collection.find(selector, options)
  if cursor
    @count = cursor.count if paginating
    cursor
  else
    []
  end
end

#group ⇒ Object

Groups the context. This will take the internally built selector and options and pass them on to the Ruby driver’s group() method on the collection. The collection itself will be retrieved from the class provided, and once the query has returned it will provided a grouping of keys with objects.

Example:

context.group

Returns:

A Hash with field values as keys, arrays of documents as values.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 117

def group
  collection.group(
    options[:fields],
    selector,
    { :group => [] },
    GROUP_REDUCE,
    true
  ).collect {|docs| docs["group"] = MongoDoc::BSON.decode(docs["group"]); docs }
end

#grouped(start, field, reduce) ⇒ Object

Common functionality for grouping operations. Currently used by min, max and sum. Will gsub the field name in the supplied reduce function.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 245

def grouped(start, field, reduce)
  result = collection.group(
    nil,
    selector,
    { start => "start" },
    reduce.gsub("[field]", field),
    true
  )
  result.empty? ? nil : result.first[start.to_s]
end

#iterate(&block) ⇒ Object

Iterate over each Document in the results. This can take an optional block to pass to each argument in the results.

Example:

context.iterate { |doc| p doc }



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# File 'lib/mongo_doc/contexts/mongo.rb', line 143

def iterate(&block)
  return caching(&block) if criteria.cached?
  if block_given?
    execute.each do |doc|
      yield doc
    end
  end
end

#last ⇒ Object

Return the last result for the Context. Essentially does a find_one on the collection with the sorting reversed. If no sorting parameters have been provided it will default to ids.

Example:

context.last

Returns:

The last document in the collection.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 163

def last
  sorting = options[:sort] || [[:_id, :asc]]
  options[:sort] = sorting.collect { |option| [ option[0], option[1].invert ] }
  collection.find_one(selector, options)
end

#max(field) ⇒ Object

Return the max value for a field.

This will take the internally built selector and options and pass them on to the Ruby driver’s group() method on the collection. The collection itself will be retrieved from the class provided, and once the query has returned it will provided a grouping of keys with sums.

Example:

context.max(:age)

Returns:

A numeric max value.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 185

def max(field)
  grouped(:max, field.to_s, MAX_REDUCE)
end

#min(field) ⇒ Object

Return the min value for a field.

This will take the internally built selector and options and pass them on to the Ruby driver’s group() method on the collection. The collection itself will be retrieved from the class provided, and once the query has returned it will provided a grouping of keys with sums.

Example:

context.min(:age)

Returns:

A numeric minimum value.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 205

def min(field)
  grouped(:min, field.to_s, MIN_REDUCE)
end

#one ⇒ Object Also known as: first

Return the first result for the Context.

Example:

context.one

Return:

The first document in the collection.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 218

def one
  collection.find_one(selector, options)
end

#sum(field) ⇒ Object

Sum the context.

This will take the internally built selector and options and pass them on to the Ruby driver’s group() method on the collection. The collection itself will be retrieved from the class provided, and once the query has returned it will provided a grouping of keys with sums.

Example:

context.sum(:age)

Returns:

A numeric value that is the sum.



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# File 'lib/mongo_doc/contexts/mongo.rb', line 239

def sum(field)
  grouped(:sum, field.to_s, SUM_REDUCE)
end