Class Mongoid::Criteria
In: lib/mongoid/criteria.rb
Parent: Object

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.

@example Create and execute a criteria.

  criteria = Criteria.new
  criteria.only(:field).where(:field => "value").skip(20).limit(20)
  criteria.execute

Methods

+   -   ==   as_json   collection   comparable   context   driver   each   exists?   extract_id   freeze   fuse   initialize_copy   merge   method_missing   new   raise_invalid   respond_to?   scoped   search   update_selector  

Included Modules

Enumerable Criterion::Builder Criterion::Creational Criterion::Exclusion Criterion::Inclusion Criterion::Inspection Criterion::Optional

External Aliases

to_a -> to_ary

Attributes

documents  [RW] 
embedded  [RW] 
field_list  [RW] 
ids  [RW] 
klass  [RW] 
options  [RW] 
selector  [RW] 

Public Class methods

Create the new Criteria object. This will initialize the selector and options hashes, as well as the type of criteria.

@example Instantiate a new criteria.

  Criteria.new(Model, true)

@param [ Class ] klass The model the criteria is for. @param [ true, false ] embedded Is the criteria for embedded docs.

Public Instance methods

Concatinate the criteria with another enumerable. If the other is a Criteria then it needs to get the collection from it.

@example Concat 2 criteria.

  criteria + criteria

@param [ Criteria ] other The other criteria.

Returns the difference between the criteria and another enumerable. If the other is a Criteria then it needs to get the collection from it.

@example Get the difference of 2 criteria.

  criteria - criteria

@param [ Criteria ] other The other criteria.

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.

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.

Get the collection associated with the criteria.

@example Get the collection.

  criteria.collection

@return [ Collection ] The collection.

@since 2.2.0

Return or create the context in which this criteria should be executed.

This will return an Enumerable context if the class is embedded, otherwise it will return a Mongo context for root classes.

@example Get the appropriate context.

  criteria.context

@return [ Mongo, Enumerable ] The appropriate context.

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

@example Iterate over the criteria results.

  criteria.each { |doc| p doc }

@return [ Criteria ] The criteria itself.

Return true if the criteria has some Document or not.

@example Are there any documents for the criteria?

  criteria.exists?

@return [ true, false ] If documents match.

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

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

Merges the supplied argument hash into a single criteria

@example Fuse the criteria and the object.

  criteria.fuse(:where => { :field => "value"}, :limit => 20)

@param [ Hash ] criteria_conditions Criteria keys and values.

@return [ Criteria ] self.

Merges another object with this Criteria and returns a new criteria. The other object may be a Criteria or a Hash. This is used to combine multiple scopes together, where a chained scope situation may be desired.

@example Merge the criteria with a conditions hash.

  criteria.merge({ :conditions => { :title => "Sir" } })

@example Merge the criteria with another criteria.

  criteri.merge(other_criteria)

@param [ Criteria, Hash ] other The other criterion to merge with.

@return [ Criteria ] A cloned self.

Convenience method of raising an invalid options error.

@example Raise the error.

  criteria.raise_invalid

@raise [ Errors::InvalidOptions ] The error.

@since 2.0.0

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.

Returns the selector and options as a Hash that would be passed to a scope for use with named scopes.

@example Get the criteria as a scoped hash.

  criteria.scoped

@return [ Hash ] The criteria as a scoped hash.

Search for documents based on a variety of args.

@example Find by an id.

  criteria.search(BSON::ObjectId.new)

@example Find by multiple ids.

  criteria.search([ BSON::ObjectId.new, BSON::ObjectId.new ])

@example Conditionally find all matching documents.

  criteria.search(:all, :conditions => { :title => "Sir" })

@example Conditionally find the first document.

  criteria.search(:first, :conditions => { :title => "Sir" })

@example Conditionally find the last document.

  criteria.search(:last, :conditions => { :title => "Sir" })

@param [ Symbol, BSON::ObjectId, Array<BSON::ObjectId> ] arg The

  argument to search with.

@param [ Hash ] options The options to search with.

@return [ Array<Symbol, Criteria> ] The type and criteria.

@since 2.0.0

Protected Instance methods

Return the entries of the other criteria or the object. Used for comparing criteria or an enumerable.

@example Get the comparable version.

  criteria.comparable(other)

@param [ Criteria ] other Another criteria.

@return [ Array ] The array to compare with.

Get the raw driver collection from the criteria.

@example Get the raw driver collection.

  criteria.driver

@return [ Mongo::Collection ] The driver collection.

@since 2.2.0

Clone or dup the current Criteria. This will return a new criteria with the selector, options, klass, embedded options, etc intact.

@example Clone a criteria.

  criteria.clone

@example Dup a criteria.

  criteria.dup

@param [ Criteria ] other The criteria getting cloned.

@return [ nil ] nil.

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

Update the selector setting the operator on the value for each key in the supplied attributes Hash.

@example Update the selector.

  criteria.update_selector({ :field => "value" }, "$in")

@param [ Hash, Array ] attributes The values to convert and apply. @param [ String ] operator The MongoDB operator. @param [ Symbol ] combine The operator to use when combining sets.

[Validate]