Queries

Queries#

CouchbaseOrm provides a rich query DSL inspired by ActiveRecord. A trivial query looks as follows:

Band.where(name: "Depeche Mode")

A more complex query utilizing various CouchbaseOrm features could be as follows:

Band.
  where(:founded.gte => "1980-01-01").
  where(name: [ "Tool", "Deftones" ]).

The query methods return CouchbaseOrm::Relation::CouchbaseOrm_Relation objects, which are chainable and lazily evaluated wrappers for Couchbase query language (SQL). The queries are executed when their result sets are iterated. For example:

# Construct a CouchbaseOrm_Relation object:

Band.where(name: 'Deftones')
# => #<CouchbaseOrm::Relation::CouchbaseOrm_Relation
#   where: [{"name"=>"Deftones"}]
#   model:    Band>

# Evaluate the query and get matching documents:

Band.where(name: 'Deftones').to_a
# => [#<Band _id: 5ebdeddfe1b83265a376a760, name: "Deftones", description: nil>]

Methods like first and last return the individual documents immediately. Otherwise, iterating a CouchbaseOrm_Relation object with methods like each or map retrieves the documents from the server. to_a can be used to force execution of a query that returns an array of documents, literally converting a CouchbaseOrm_Relation object to an Array.

When a query method is called on a CouchbaseOrm_Relation instance, the method returns a new CouchbaseOrm_Relation instance with the new conditions added to the existing conditions:

scope = Band.where(:founded.gte => "1980-01-01")
# => #<CouchbaseOrm::Relation::CouchbaseOrm_Relation
#   where: [{"founded"=>{"$gte"=>"1980-01-01"}}]
#   model:    Band>

scope.where(:founded.lte => "2020-01-01")
# => #<CouchbaseOrm::Relation::CouchbaseOrm_Relation
#   where: [{"founded"=>{"$gte"=>"1980-01-01", "$lte"=>"2020-01-01"}}]
#   model:    Band>

scope
# => #<CouchbaseOrm::Relation::CouchbaseOrm_Relation
#   where: [{"founded"=>{"$gte"=>"1980-01-01"}}]
#   class:    Band>

Condition Syntax#

CouchbaseOrm supports three ways of specifying individual conditions:

  1. Attribute syntax.

  2. SQL syntax.

  3. Symbol operator syntax.

All syntaxes support querying embedded documents using the dot notation. All syntaxes respect attribute types, if the attribute being queried is defined in the model class, and attribute aliases.

The examples in this section use the following model definition:

class Band < CouchbaseOrm::Base

  attribute :name, type: String
  attribute :founded, type: Integer
  attribute :m, as: :member_count, type: Integer

  belongs_to :manager
end

class Manager < CouchbaseOrm::Base

  has_many :band

  attribute :name, type: String
end

Attribute Syntax#

The simplest querying syntax utilizes the basic Ruby hashes. Keys can be symbols or strings, and correspond to attribute names in Couchbase documents:

Band.where(name: "Depeche Mode")
#   => #<CouchbaseOrm::Relation::CouchbaseOrm_Relation
#   where: [{"name"=>"Depeche Mode"}]
#   model:    Band>

# Equivalent to:

Band.where("name" => "Depeche Mode")

SQL Syntax#

An SQL operator may be specified on any attribute using the string syntax:

Band.where(founded: {'$gt' => 1980})
# => #<CouchbaseOrm::Relation::CouchbaseOrm_Relation
#   where: [{"founded"=>{"$gt"=>1980}}]
#   model:  Band>

# Equivalent to:

Band.where('founded > 1980')

Logical Operations#

CouchbaseOrm supports where and not logical operations on CouchbaseOrm_Relation objects. These methods take one hash of conditions.

# and with conditions
Band.where(label: 'Trust in Trance').where(name: 'Astral Projection')

not Behavior#

not method can be called without arguments, in which case it will negate the next condition that is specified. not can also be called with one or more hash conditions or CouchbaseOrm_Relation objects, which will all be negated and added to the criteria.

# not negates subsequent where
Band.not.where(name: 'Best')
# => {"name"=>{"$ne"=>"Best"}}

# not negates its argument
Band.not(name: 'Best')
# => {"name"=>{"$ne"=>"Best"}}

Ordering#

CouchbaseOrm provides the order method on CouchbaseOrm_Relation objects and its alias, order_by, to specify the ordering of documents. These methods take a hash indicating which attributes to order the documents by, and whether to use ascending or descending order for each attribute.

Band.order(name: asc)
# => #<CouchbaseOrm::Relation::CouchbaseOrm_Relation
#   where: []
#   order:  [{"name"=>asc}]
#   model:    Band>

Band.order_by(name: :desc, description: :asc)
# => #<CouchbaseOrm::Relation::CouchbaseOrm_Relation
#   where: []
#   order:  [{"name"=>:desc}, {"description"=>:asc}]
#   class:    Band
#   embedded: false>

The direction may be specified with Symbol :asc and :desc for ascending and descending, respectively

Finding By _id#

CouchbaseOrm provides the find method on CouchbaseOrm_Relation objects to find documents by their _id values:

Band.find('5f0e41d92c97a64a26aabd10')
# => #<Band _id: 5f0e41d92c97a64a26aabd10, name: "Juno Reactor">

The find method can accept an array of arguments. In either case each of the arguments or array elements is taken to be an _id value, and documents with all of the specified _id values are returned in an array:

Band.find('5f0e41d92c97a64a26aabd10', '5f0e41b02c97a64a26aabd0e')
# => [#<Band _id: 5f0e41b02c97a64a26aabd0e, name: "SUN Project", description: nil, likes: nil>,
  #<Band _id: 5f0e41d92c97a64a26aabd10, name: "Juno Reactor", description: nil, likes: nil>]

Band.find(['5f0e41d92c97a64a26aabd10', '5f0e41b02c97a64a26aabd0e'])
# => [#<Band _id: 5f0e41b02c97a64a26aabd0e, name: "SUN Project", description: nil, likes: nil>,
  #<Band _id: 5f0e41d92c97a64a26aabd10, name: "Juno Reactor", description: nil, likes: nil>]

If any of the _id values are not found in the database, the behavior of find depends on the value of the quiet configuration option. If the option is set to false, find raises CouchbaseOrm::Errors::DocumentNotFound if any of the _ids are not found. If the option is set to true and find is given a single _id to find and there is no matching document, find returns nil. If the option is set to false and find is given an array of ids to find and some are not found, the return value is an array of documents that were found (which could be empty if no documents were found at all).

Additional Query Methods#

CouchbaseOrm also has some helpful methods on criteria.

Operation

Example

CouchbaseOrm_Relation#count

Get the total number of documents matching a filter, or the total number of documents in a collection. Note this will always hit the database for the count.

 
Band.count
Band.where(name: "Photek").count

CouchbaseOrm_Relation#each

Iterate over all matching documents in the criteria.

 
Band.where(members: 1).each do |band|
  p band.name
end

CouchbaseOrm_Relation#find_by

Find a document by the provided attributes. If not found, raise an error or return nil depending on the value of the raise_not_found_error configuration option.

 
Band.find_by(name: "Photek")

Band.find_by(name: "Tool") do |band|
  band.impressions += 1
end

CouchbaseOrm_Relation#first|last

Finds a single document given the provided criteria. Get a list of documents by passing in a limit argument. This method automatically adds a sort on _id. This can cause performance issues, so if the sort is undesirable, CouchbaseOrm_Relation#take can be used instead.

 
Band.first
Band.where(:members.with_size => 3).first
Band.where(:members.with_size => 3).last
Band.first(2)

CouchbaseOrm_Relation#length|size

Same as count but caches subsequent calls to the database

 
Band.length
Band.where(name: "FKA Twigs").size

CouchbaseOrm_Relation#pluck

Get all the values for the provided attribute. Returns nil for unset attributes and for non-existent attributes.

 
Band.all.pluck(:name)
  #=> ["Daft Punk", "Aphex Twin", "Ween"]

Band.all.pluck('address.city')
  #=> ["Paris", "Limerick", "New Hope"]

# Using the earlier definition of Manager,
# expands out to "managers.name" in the query:
Band.all.pluck('managers.n')
  #=> [ ["Berry Gordy", "Tommy Mottola"], [], ["Quincy Jones"] ]

# Accepts multiple attribute arguments, in which case
# the result will be returned as an Array of Arrays.
Band.all.pluck(:name, :likes)
  #=> [ ["Daft Punk", 342], ["Aphex Twin", 98], ["Ween", 227] ]

Class Methods#

Class methods on models that return criteria objects are also treated like scopes, and can be chained as well.

class Band < CouchbaseOrm::Base
  attribute :name, type: String
  attribute :active, type: Boolean, default: true

  def self.active
    where(active: true)
  end
end

Band.active
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