Class: Mongoid::Criteria

Inherits:
Object
  • Object
show all
Includes:
Enumerable, Mongoid::Clients::Options, Contextual, Inspectable, Marshalable, Modifiable, Findable, Scopable, Origin::Queryable
Defined in:
lib/mongoid/criteria.rb,
lib/mongoid/criteria/scopable.rb,
lib/mongoid/criteria/findable.rb,
lib/mongoid/criteria/permission.rb,
lib/mongoid/criteria/modifiable.rb,
lib/mongoid/criteria/marshalable.rb,
lib/mongoid/criteria/inspectable.rb

Overview

The Criteria class is the core object needed in Mongoid to retrieve objects from the database. It is a DSL that essentially sets up the selector and options arguments that get passed on to a Mongo::Collection in the Ruby driver. Each method on the Criteria returns self to they can be chained in order to create a readable criterion to be executed against the database.

Defined Under Namespace

Modules: Findable, Inspectable, Marshalable, Modifiable, Permission, Scopable

Constant Summary

CHECK =

Static array used to check with method missing - we only need to ever instantiate once.

Since:

  • 4.0.0

[]

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Mongoid::Clients::Options

#collection_name, #mongo_client, #persistence_options, #with

Methods included from Modifiable

#build, #create, #create!, #find_or_create_by, #find_or_create_by!, #find_or_initialize_by, #first_or_create, #first_or_create!, #first_or_initialize

Methods included from Marshalable

#marshal_dump, #marshal_load

Methods included from Inspectable

#inspect

Methods included from Findable

#count, #empty?, #exists?, #find, #find_by, #find_by!, #first, #last

Methods included from Contextual

#context

Constructor Details

#initialize(klass) ⇒ Criteria

Initialize the new criteria.

Examples:

Init the new criteria.

Criteria.new(Band)

Since:

  • 1.0.0



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# File 'lib/mongoid/criteria.rb', line 192

def initialize(klass)
  @klass = klass
  klass ? super(klass.aliased_fields, klass.fields) : super({}, {})
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(name, *args, &block) ⇒ Object (private)

Used for chaining Criteria scopes together in the for of class methods on the Document the criteria is for.

Examples:

Handle method missing.

criteria.method_missing(:name)

Since:

  • 1.0.0



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# File 'lib/mongoid/criteria.rb', line 548

def method_missing(name, *args, &block)
  if klass.respond_to?(name)
    klass.send(:with_scope, self) do
      klass.send(name, *args, &block)
    end
  elsif CHECK.respond_to?(name)
    return entries.send(name, *args, &block)
  else
    super
  end
end

Instance Attribute Details

#embeddedObject

Returns the value of attribute embedded



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# File 'lib/mongoid/criteria.rb', line 33

def embedded
  @embedded
end

#klassObject

Returns the value of attribute klass



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# File 'lib/mongoid/criteria.rb', line 33

def klass
  @klass
end

#metadataObject

Returns the value of attribute metadata



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# File 'lib/mongoid/criteria.rb', line 33

def 
  @metadata
end

#parent_documentObject

Returns the value of attribute parent_document



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# File 'lib/mongoid/criteria.rb', line 33

def parent_document
  @parent_document
end

Instance Method Details

#==(other) ⇒ true, false

Note:

This will force a database load when called if an enumerable is passed.

Returns true if the supplied Enumerable or Criteria is equal to the results of this Criteria or the criteria itself.

Since:

  • 1.0.0



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# File 'lib/mongoid/criteria.rb', line 45

def ==(other)
  return super if other.respond_to?(:selector)
  entries == other
end

#as_json(options = nil) ⇒ String

Needed to properly get a criteria back as json

Examples:

Get the criteria as json.

Person.where(:title => "Sir").as_json


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# File 'lib/mongoid/criteria.rb', line 58

def as_json(options = nil)
  entries.as_json(options)
end

#cacheCriteria

Tells the criteria that the cursor that gets returned needs to be cached. This is so multiple iterations don't hit the database multiple times, however this is not advisable when working with large data sets as the entire results will get stored in memory.

Examples:

Flag the criteria as cached.

criteria.cache


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# File 'lib/mongoid/criteria.rb', line 71

def cache
  crit = clone
  crit.options.merge!(cache: true)
  crit
end

#cached?true, false

Will return true if the cache option has been set.

Examples:

Is the criteria cached?

criteria.cached?


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# File 'lib/mongoid/criteria.rb', line 83

def cached?
  options[:cache] == true
end

#documentsArray<Document>

Get the documents from the embedded criteria.

Examples:

Get the documents.

criteria.documents

Since:

  • 3.0.0



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# File 'lib/mongoid/criteria.rb', line 95

def documents
  @documents ||= []
end

#documents=(docs) ⇒ Array<Document>

Set the embedded documents on the criteria.

Examples:

Set the documents.

Since:

  • 3.0.0



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# File 'lib/mongoid/criteria.rb', line 108

def documents=(docs)
  @documents = docs
end

#embedded?true, false

Is the criteria for embedded documents?

Examples:

Is the criteria for embedded documents?

criteria.embedded?

Since:

  • 3.0.0



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# File 'lib/mongoid/criteria.rb', line 120

def embedded?
  !!@embedded
end

#empty_and_chainable?true, false

Is the criteria an empty but chainable criteria?

Examples:

Is the criteria a none criteria?

criteria.empty_and_chainable?

Since:

  • 4.0.0



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# File 'lib/mongoid/criteria.rb', line 320

def empty_and_chainable?
  !!@none
end

#extract_idObject

Extract a single id from the provided criteria. Could be in an $and query or a straight _id query.

Examples:

Extract the id.

criteria.extract_id

Since:

  • 2.3.0



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# File 'lib/mongoid/criteria.rb', line 133

def extract_id
  selector.extract_id
end

#extras(extras) ⇒ Criteria

Adds a criterion to the Criteria that specifies additional options to be passed to the Ruby driver, in the exact format for the driver.

criteria.extras(:limit => 20, :skip => 40)

Examples:

Add extra params to the criteria.

Since:

  • 2.0.0



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# File 'lib/mongoid/criteria.rb', line 148

def extras(extras)
  crit = clone
  crit.options.merge!(extras)
  crit
end

#field_listArray<String>

Get the list of included fields.

Examples:

Get the field list.

criteria.field_list

Since:

  • 2.0.0



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# File 'lib/mongoid/criteria.rb', line 162

def field_list
  if options[:fields]
    options[:fields].keys.reject{ |key| key == "_type" }
  else
    []
  end
end

#for_js(javascript, scope = {}) ⇒ Criteria

Find documents by the provided javascript and scope. Uses a $where but is different from Criteria#where in that it will pass a code object to the query instead of a pure string. Safe against Javascript injection attacks.

Examples:

Find by javascript.

Band.for_js("this.name = param", param: "Tool")

Since:

  • 3.1.0



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# File 'lib/mongoid/criteria.rb', line 485

def for_js(javascript, scope = {})
  js_query(BSON::CodeWithScope.new(javascript, scope))
end

#freezeCriteria

When freezing a criteria we need to initialize the context first otherwise the setting of the context on attempted iteration will raise a runtime error.

Examples:

Freeze the criteria.

criteria.freeze

Since:

  • 2.0.0



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# File 'lib/mongoid/criteria.rb', line 180

def freeze
  context and inclusions and super
end

#includes(*relations) ⇒ Criteria

Note:

This will work for embedded relations that reference another collection via belongs_to as well.

Note:

Eager loading brings all the documents into memory, so there is a sweet spot on the performance gains. Internal benchmarks show that eager loading becomes slower around 100k documents, but this will naturally depend on the specific application.

Eager loads all the provided relations. Will load all the documents into the identity map who's ids match based on the extra query for the ids.

Examples:

Eager load the provided relations.

Person.includes(:posts, :game)

Since:

  • 2.2.0



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# File 'lib/mongoid/criteria.rb', line 218

def includes(*relations)
  relations.flatten.each do |name|
     = klass.reflect_on_association(name)
    raise Errors::InvalidIncludes.new(klass, relations) unless 
    inclusions.push() unless inclusions.include?()
  end
  clone
end

#inclusionsArray<Metadata>

Get a list of criteria that are to be executed for eager loading.

Examples:

Get the eager loading inclusions.

Person.includes(:game).inclusions

Since:

  • 2.2.0



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# File 'lib/mongoid/criteria.rb', line 235

def inclusions
  @inclusions ||= []
end

#inclusions=(value) ⇒ Array<Metadata>

Set the inclusions for the criteria.

Examples:

Set the inclusions.

criteria.inclusions = [ meta ]

Since:

  • 3.0.0



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# File 'lib/mongoid/criteria.rb', line 249

def inclusions=(value)
  @inclusions = value
end

#merge(other) ⇒ Criteria

criteria.merge({

  klass: Band,
  where: { name: "Depeche Mode" },
  order_by: { name: 1 }
})


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# File 'lib/mongoid/criteria.rb', line 273

def merge(other)
  crit = clone
  crit.merge!(other)
  crit
end

#merge!(other) ⇒ Criteria

Merge the other criteria into this one.

Examples:

Merge another criteria into this criteria.

criteria.merge(Person.where(name: "bob"))

Since:

  • 3.0.0



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# File 'lib/mongoid/criteria.rb', line 289

def merge!(other)
  criteria = other.to_criteria
  selector.merge!(criteria.selector)
  options.merge!(criteria.options)
  self.documents = criteria.documents.dup unless criteria.documents.empty?
  self.scoping_options = criteria.scoping_options
  self.inclusions = (inclusions + criteria.inclusions).uniq
  self
end

#noneCriteria

Returns a criteria that will always contain zero results and never hits the database.

Examples:

Return a none criteria.

criteria.none

Since:

  • 4.0.0



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# File 'lib/mongoid/criteria.rb', line 308

def none
  @none = true and self
end

#only(*args) ⇒ Criteria

Overriden to include _type in the fields.

Examples:

Limit the fields returned from the database.

Band.only(:name)

Since:

  • 1.0.0



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# File 'lib/mongoid/criteria.rb', line 334

def only(*args)
  return clone if args.flatten.empty?
  args = args.flatten
  if (args & Fields::IDS).empty?
    args.unshift(:_id)
  end
  if klass.hereditary?
    super(*args.push(:_type))
  else
    super(*args)
  end
end

#read(value = nil) ⇒ Criteria

Set the read preference for the criteria.

Examples:

Set the read preference.

criteria.read(mode: :primary_preferred)

Since:

  • 5.0.0



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# File 'lib/mongoid/criteria.rb', line 357

def read(value = nil)
  clone.tap do |criteria|
    criteria.options.merge!(read: value)
  end
end

#respond_to?(name, include_private = false) ⇒ true, false

Returns true if criteria responds to the given method.

Examples:

Does the criteria respond to the method?

crtiteria.respond_to?(:each)


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# File 'lib/mongoid/criteria.rb', line 387

def respond_to?(name, include_private = false)
  super || klass.respond_to?(name) || CHECK.respond_to?(name, include_private)
end

#to_criteriaCriteria

Convenience for objects that want to be merged into a criteria.

Examples:

Convert to a criteria.

criteria.to_criteria

Since:

  • 3.0.0



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# File 'lib/mongoid/criteria.rb', line 401

def to_criteria
  self
end

#to_procProc

Convert the criteria to a proc.

Examples:

Convert the criteria to a proc.

criteria.to_proc

Since:

  • 3.0.0



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# File 'lib/mongoid/criteria.rb', line 413

def to_proc
  ->{ self }
end

#type(types) ⇒ Criteria

Adds a criterion to the Criteria that specifies a type or an Array of types that must be matched.

Examples:

Match only specific models.

criteria.type('Browser')
criteria.type(['Firefox', 'Browser'])


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# File 'lib/mongoid/criteria.rb', line 427

def type(types)
  any_in(_type: Array(types))
end

#where(expression) ⇒ Criteria

This is the general entry point for most MongoDB queries. This either creates a standard field: value selection, and expanded selection with the use of hash methods, or a $where selection if a string is provided.

Examples:

Add a standard selection.

criteria.where(name: "syd")

Add a javascript selection.

criteria.where("this.name == 'syd'")

Raises:

  • (UnsupportedJavascript)

    If provided a string and the criteria is embedded.

Since:

  • 1.0.0



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# File 'lib/mongoid/criteria.rb', line 449

def where(expression)
  if expression.is_a?(::String) && embedded?
    raise Errors::UnsupportedJavascript.new(klass, expression)
  end
  super
end

#without(*args) ⇒ Criteria

Overriden to exclude _id from the fields.

Examples:

Exclude fields returned from the database.

Band.without(:name)

Since:

  • 4.0.3



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# File 'lib/mongoid/criteria.rb', line 373

def without(*args)
  args -= Fields::IDS
  super(*args)
end

#without_optionsCriteria

Get a version of this criteria without the options.

Examples:

Get the criteria without options.

criteria.without_options

Since:

  • 3.0.4



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# File 'lib/mongoid/criteria.rb', line 465

def without_options
  crit = clone
  crit.options.clear
  crit
end