class Mongoid::Criteria
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.
Constants
- CHECK
Static array used to check with method missing - we only need to ever instantiate once.
@since 4.0.0
Attributes
Public Class Methods
Initialize the new criteria.
@example Init the new criteria.
Criteria.new(Band)
@param [ Class ] klass The model class.
@since 1.0.0
# File lib/mongoid/criteria.rb, line 192 def initialize(klass) @klass = klass klass ? super(klass.aliased_fields, klass.fields) : super({}, {}) end
Public Instance Methods
Returns true if the supplied Enumerable
or
Criteria
is equal to the results of this Criteria
or the criteria itself.
@note This will force a database load when called if an enumerable is passed.
@param [ Object ] other The other
Enumerable
or Criteria
to compare to.
@return [ true, false ] If the objects are equal.
@since 1.0.0
# File lib/mongoid/criteria.rb, line 45 def ==(other) return super if other.respond_to?(:selector) entries == other end
Needed to properly get a criteria back as json
@example Get the criteria as json.
Person.where(:title => "Sir").as_json
@param [ Hash ] options Options to pass through to the serializer.
@return [ String ] The JSON string.
# File lib/mongoid/criteria.rb, line 58 def as_json(options = nil) entries.as_json(options) end
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.
@example Flag the criteria as cached.
criteria.cache
@return [ Criteria ] The cloned criteria.
# File lib/mongoid/criteria.rb, line 71 def cache crit = clone crit.options.merge!(cache: true) crit end
Will return true if the cache option has been set.
@example Is the criteria cached?
criteria.cached?
@return [ true, false ] If the criteria is flagged as cached.
# File lib/mongoid/criteria.rb, line 83 def cached? options[:cache] == true end
Get the documents from the embedded criteria.
@example Get the documents.
criteria.documents
@return [ Array<Document> ] The documents.
@since 3.0.0
# File lib/mongoid/criteria.rb, line 95 def documents @documents ||= [] end
Set the embedded documents on the criteria.
@example Set the documents.
@param [ Array<Document> ] docs The embedded documents.
@return [ Array<Document> ] The embedded documents.
@since 3.0.0
# File lib/mongoid/criteria.rb, line 108 def documents=(docs) @documents = docs end
Is the criteria for embedded documents?
@example Is the criteria for embedded documents?
criteria.embedded?
@return [ true, false ] If the criteria is embedded.
@since 3.0.0
# File lib/mongoid/criteria.rb, line 120 def embedded? !!@embedded end
Is the criteria an empty but chainable criteria?
@example Is the criteria a none criteria?
criteria.empty_and_chainable?
@return [ true, false ] If the criteria is a none.
@since 4.0.0
# File lib/mongoid/criteria.rb, line 320 def empty_and_chainable? !!@none end
Extract a single id from the provided criteria. Could be in an $and query or a straight _id query.
@example Extract the id.
criteria.extract_id
@return [ Object ] The id.
@since 2.3.0
# File lib/mongoid/criteria.rb, line 133 def extract_id selector.extract_id end
Adds a criterion to the Criteria
that specifies additional
options to be passed to the Ruby driver, in the exact format for the
driver.
@example Add extra params to the criteria. criteria.extras(:limit => 20, :skip => 40)
@param [ Hash ] extras The extra driver options.
@return [ Criteria ] The cloned criteria.
@since 2.0.0
# File lib/mongoid/criteria.rb, line 148 def extras(extras) crit = clone crit.options.merge!(extras) crit end
Get the list of included fields.
@example Get the field list.
criteria.field_list
@return [ Array<String> ] The fields.
@since 2.0.0
# File lib/mongoid/criteria.rb, line 162 def field_list if options[:fields] options[:fields].keys.reject{ |key| key == "_type" } else [] end end
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.
@example Find by javascript.
Band.for_js("this.name = param", param: "Tool")
@param [ String ] javascript The javascript to execute in the $where. @param [ Hash ] scope The scope for the code.
@return [ Criteria ] The criteria.
@since 3.1.0
# File lib/mongoid/criteria.rb, line 451 def for_js(javascript, scope = {}) js_query(BSON::CodeWithScope.new(javascript, scope)) end
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.
@example Freeze the criteria.
criteria.freeze
@return [ Criteria ] The frozen criteria.
@since 2.0.0
# File lib/mongoid/criteria.rb, line 180 def freeze context and inclusions and super end
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.
@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.
@example Eager load the provided relations.
Person.includes(:posts, :game)
@param [ Array<Symbol> ] relations The names of the relations to eager
load.
@return [ Criteria ] The cloned criteria.
@since 2.2.0
# File lib/mongoid/criteria.rb, line 218 def includes(*relations) relations.flatten.each do |name| metadata = klass.reflect_on_association(name) raise Errors::InvalidIncludes.new(klass, relations) unless metadata inclusions.push(metadata) unless inclusions.include?(metadata) end clone end
Get a list of criteria that are to be executed for eager loading.
@example Get the eager loading inclusions.
Person.includes(:game).inclusions
@return [ Array<Metadata> ] The inclusions.
@since 2.2.0
# File lib/mongoid/criteria.rb, line 235 def inclusions @inclusions ||= [] end
Set the inclusions for the criteria.
@example Set the inclusions.
criteria.inclusions = [ meta ]
@param [ Array<Metadata> ] The inclusions.
@return [ Array<Metadata> ] The new inclusions.
@since 3.0.0
# File lib/mongoid/criteria.rb, line 249 def inclusions=(value) @inclusions = value end
Merge the other criteria into this one.
@example Merge another criteria into this criteria.
criteria.merge(Person.where(name: "bob"))
@param [ Criteria ] other The criteria to merge in.
@return [ Criteria ] The merged criteria.
@since 3.0.0
# 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.dup).uniq self end
Returns a criteria that will always contain zero results and never hits the database.
@example Return a none criteria.
criteria.none
@return [ Criteria ] The none criteria.
@since 4.0.0
# File lib/mongoid/criteria.rb, line 308 def none @none = true and self end
Overriden to include _type in the fields.
@example Limit the fields returned from the database.
Band.only(:name)
@param [ Array<Symbol> ] args The names of the fields.
@return [ Criteria ] The cloned criteria.
@since 1.0.0
# File lib/mongoid/criteria.rb, line 334 def only(*args) return clone if args.flatten.empty? args = args.flatten if klass.hereditary? super(*args.push(:_type)) else super(*args) end end
Returns true if criteria responds to the given method.
@example Does the criteria respond to the method?
crtiteria.respond_to?(:each)
@param [ Symbol ] name The name of the class
method on the Document
. @param [ true, false ] include_private
Whether to include privates.
@return [ true, false ] If the criteria responds to the method.
# File lib/mongoid/criteria.rb, line 353 def respond_to?(name, include_private = false) super || klass.respond_to?(name) || CHECK.respond_to?(name, include_private) end
Convenience for objects that want to be merged into a criteria.
@example Convert to a criteria.
criteria.to_criteria
@return [ Criteria ] self.
@since 3.0.0
# File lib/mongoid/criteria.rb, line 367 def to_criteria self end
Convert the criteria to a proc.
@example Convert the criteria to a proc.
criteria.to_proc
@return [ Proc ] The wrapped criteria.
@since 3.0.0
# File lib/mongoid/criteria.rb, line 379 def to_proc ->{ self } end
Adds a criterion to the Criteria
that specifies a type or an
Array of types that must be matched.
@example Match only specific models.
criteria.type('Browser') criteria.type(['Firefox', 'Browser'])
@param [ Array<String> ] types The types to match against.
@return [ Criteria ] The cloned criteria.
# File lib/mongoid/criteria.rb, line 393 def type(types) any_in(_type: Array(types)) end
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.
@example Add a standard selection.
criteria.where(name: "syd")
@example Add a javascript selection.
criteria.where("this.name == 'syd'")
@param [ String, Hash ] criterion The javascript or standard selection.
@raise [ UnsupportedJavascript ] If provided a string and the criteria
is embedded.
@return [ Criteria ] The cloned selectable.
@since 1.0.0
# File lib/mongoid/criteria.rb, line 415 def where(expression) if expression.is_a?(::String) && embedded? raise Errors::UnsupportedJavascript.new(klass, expression) end super end
Get a version of this criteria without the options.
@example Get the criteria without options.
criteria.without_options
@return [ Criteria ] The cloned criteria.
@since 3.0.4
# File lib/mongoid/criteria.rb, line 431 def without_options crit = clone crit.options.clear crit end
Private Instance Methods
Are documents in the query missing, and are we configured to raise an error?
@api private
@example Check for missing documents.
criteria.check_for_missing_documents!([], [ 1 ])
@param [ Array<Document> ] result The result. @param [ Array<Object> ] ids The ids.
@raise [ Errors::DocumentNotFound ] If none are found and raising an
error.
@since 3.0.0
# File lib/mongoid/criteria.rb, line 472 def check_for_missing_documents!(result, ids) if (result.size < ids.size) && Mongoid.raise_not_found_error raise Errors::DocumentNotFound.new(klass, ids, ids - result.map(&:_id)) end end
Clone or dup the current Criteria
. This will return a new
criteria with the selector, options, klass, embedded options, etc intact.
@api private
@example Clone a criteria.
criteria.clone
@example Dup a criteria.
criteria.dup
@param [ Criteria ] other The criteria getting cloned.
@return [ nil ] nil.
@since 1.0.0
# File lib/mongoid/criteria.rb, line 494 def initialize_copy(other) @inclusions = other.inclusions.dup @scoping_options = other.scoping_options @documents = other.documents.dup @context = nil super end
For models where inheritance is at play we need to add the type selection.
@example Add the type selection.
criteria.merge_type_selection
@return [ true, false ] If type selection was added.
@since 3.0.3
# File lib/mongoid/criteria.rb, line 535 def merge_type_selection selector.merge!(type_selection) if type_selectable? end
Used for chaining Criteria
scopes together in the for of class
methods on the Document
the criteria is for.
@example Handle method missing.
criteria.method_missing(:name)
@param [ Symbol ] name The method name. @param [ Array ] args The arguments.
@return [ Object ] The result of the method call.
@since 1.0.0
# File lib/mongoid/criteria.rb, line 514 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
Get a new selector with type selection in it.
@api private
@example Get a selector with type selection.
criteria.selector_with_type_selection
@return [ Hash ] The selector.
@since 3.0.3
# File lib/mongoid/criteria.rb, line 579 def selector_with_type_selection type_selectable? ? selector.merge(type_selection) : selector end
Is the criteria type selectable?
@api private
@example If the criteria type selectable?
criteria.type_selectable?
@return [ true, false ] If type selection should be added.
@since 3.0.3
# File lib/mongoid/criteria.rb, line 549 def type_selectable? klass.hereditary? && !selector.keys.include?("_type") && !selector.keys.include?(:_type) end
Get the selector for type selection.
@api private
@example Get a type selection hash.
criteria.type_selection
@return [ Hash ] The type selection.
@since 3.0.3
# File lib/mongoid/criteria.rb, line 565 def type_selection { _type: { "$in" => klass._types }} end