A Ruby ORM for RethinkDB


NoBrainer uses a field type mechanism to automatically cast and validates field values. Using the type mechanism improves the integrity and security of your application.

Specifying Field Types

The following example demonstrates how to specify field types:

class User
  field :name,         :type => String
  field :biography,    :type => Text
  field :verified,     :type => Boolean
  field :num_friends,  :type => Integer
  field :last_seen_at, :type => Time
  field :status,       :type => Enum, :in => [:pending, :accepted, :rejected]

The following types are currently supported:

  • String
  • Text
  • Integer
  • Float
  • Boolean
  • Symbol
  • Enum
  • Time
  • Date
  • Binary
  • Array
  • Set
  • Hash
  • Geo::Point
  • Geo::Circle
  • Geo::Polygon
  • Geo::LineString

Model Behavior

The behavior is the following:

  • The default field type is Object, meaning that anything will do and values will be delivered to the database as is.
  • Declaring a Boolean field adds an attr? getter for convenience.
  • When assigning an attribute to a value, NoBrainer will attempt to cast the given value to the correct type in a safe manner if the value does not match the specified type as described below. If the casting operation fails, then NoBrainer leaves the value as is, meaning that reading the attribute back will return the uncasted value. This should be taken in consideration when writing before_save callbacks since incorrectly typed values may be read.
  • When performing validations, NoBrainer will check that attribute values match the specified type. If some values do not match their types, validation errors will be added to prevent the model to be persisted.
  • belongs_to foreign key associations are not type checked.
  • When data is read back from the database, no type casting is performed. For example, when reading back a field from the database with a value of "1" (a string), the field value read from the model API will always be "1" and not 1, even if the field type is declared to be an Integer. You must perform a database migration to convert all the strings into integers.

Note that the nil value is always valid and never casted. If you wish to prevent this, you may add a not_null or presence validation.

Query Behavior

NoBrainer validates and cast values passed in where() queries. When a bad value is used, a NoBrainer::Error::InvalidType exception will be raised. If left uncaught in a Rails controller, a 400 status code will be returned. For example:

class User
  include NoBrainer::Document
  field :num_friends, :type => Integer

User.create(:num_friends => 30)
User.where( => "10").first # returns the user
User.where( => "10xx").first # raises an InvalidType error



  • Strings with less than 255 characters are accepted. This length limit is configurable with config.max_string_length.
  • Symbols are accepted.


  • Strings are accepted.


  • Integers are accepted.
  • Strings are converted to integers only when the resulting integer can be converted back to the original stripped string. For example, " -4 " and "+3" are valid, but "4f" or "" are not.
  • Floats are accepted when their values matches exactly an integer.


  • Floats are accepted.
  • Integers are accepted.
  • Strings are converted to floats only when the resulting integer can be converted back to the original stripped string, excluding leading 0’s. Be aware that the current mechanism assume that the decimal separator is "."'. No localization is performed, meaning that using "," as a decimal separator will not work.


  • true and false are accepted.
  • Strings are accepted with the following rules: the lowercase stripped value must either be true, yes, t, 1 or false, no, f, 0.
  • 1 and 0 integers are accepted.


  • Symbols are accepted.
  • Non empty strings are accepted. The cast operation is value.strip.to_sym.


Enum is similar to the Symbol type, except it adds additional methods.

  • First, the :in option is mandatory when declaring an Enum field to specify the possible values.
  • Each of the values specified in the :in option generates two methods. For each allowed value, a method value? returns whether the defined field is set to value; and a method value! changes the field to value. Note that save must still be invoked to persist the changes to the database.
  • These method names can be prefixed or suffixed by specifying a :prefix or :suffix option to avoid naming conflicts.


class User
  include NoBrainer::Document
  field :status, :type => Enum, :in => [:pending, :accepted, :rejected],
                                :default => :pending
user =
user.pending? # true
user.pending?  # false
user.rejected? # true


  • Times are accepted.
  • Dates are not accepted.
  • Strings in the ISO 8601 combined date and time format are accepted. For example "2007-04-05T14:30Z" or "2007-04-05T12:30-02:00".

Note that NoBrainer can be configured with user_timezone and db_timezone to specify how timezones should be handled. Read more in the Installation section to learn more.

Read more about Time at the bottom of this page.


  • Dates are accepted.
  • Times are not accepted.
  • Strings in the ISO 8601 date format are accepted. For example "2007-04-05".
  • Any other value is ignored, and a validation error is added.

Note that Dates are persisted in the database as UTC times. This is an important consideration when querying dates due to time millisecond precision.

Read more about Date at the bottom of this page.


  • Binaries are accepted.
  • Strings are accepted.


  • Arrays containing any types are accepted.
  • Arrays containing a specific type may be specified with the of method or array literal, for example: Array.of(String) or [String]. (Starting with version 0.36.0)


  • Sets and Arrays containing any types are accepted.


  • Hashes containing any types are accepted.


  • Geo::Point are accepted.
  • Pairs of floats: [longitude, latitude].
  • Hashes {:longitude => long, :latitude => lat} or {:long => long, :lat => lat}.


  • Geo::Circle are accepted.
  • Pairs of [center, radius] where center can coerce to a Geo::Point and radius to a Float.
  • Hash {:center => center, :radius => radius}.

Additionally, you may pass options as specified in the documentation.


  • Geo::Polygon are accepted
  • Accepts an array of values coercible to a Geo::Point.


  • Geo::LineString are accepted
  • Accepts an array of values coercible to a Geo::Point.


  • Use the Time type instead. Read more below.

Custom Types

NoBrainer supports custom types. The following shows an example to define a Point type.

class Point <, :y)
  # This class method imports a user facing values into the model.
  # For example, calling an attribute setter will call this method.
  # If the given value cannot be casted safely, a
  # NoBrainer::Error::InvalidType error must be raised.
  # Otherwise, the method returns the converted value.
  def self.nobrainer_cast_user_to_model(value)
    case value
    when Point then value
    when Hash  then new(value[:x] || value['x'], value[:y] || value['y'])
    else raise NoBrainer::Error::InvalidType

  # This class method translates the given value to a compatible
  # RethinkDB type value.
  # It is used when writing to the database, for example saving a model.
  def self.nobrainer_cast_model_to_db(value)
    {'x' => value.x, 'y' => value.y}

  # This class method translates a value from the database to the proper type.
  # It is used when reading from the database.
  def self.nobrainer_cast_db_to_model(value)['x'], value['y'])

Overriding Default Behavior

If you wish to override some of the default behavior of an existing type, for example, to cast integers in an unsafe manner, you may use override the attribute setter. For example:

class User
  field :num_friends, :type => Integer

  def num_friends=(value)

Another way to override a type behavior is to define custom casting behavior similarly to custom types. For example, to parse all times with chronic, the following code will do:

class Time
  def self.nobrainer_cast_user_to_model(value)
    value = Chronic.parse(value) rescue value if value.is_a?(String)

Note that calling super() is important as it will take care of the timezone converstion if needed.

You can also subclass the Time class, add the casting method, and call it ChronicTime. The chronic time casting will only be performed if you use the ChronicTime type instead of the Time type.

Date/Time Notes

Regarding date/time types, here is what you need to know:

  • The RethinkDB driver only supports Time serialization/deserialization at this moment. In Ruby 1.9+, there is no longer the need to use the DateTime type as the Time type no longer has restrictive bounds. Nevertheless, the RethinkDB database have some limitations and are described in their documentation. Essentially, you can start to worry when you start to deal with times which year is outside of the range [1400, 10000]. See also this post.
  • Times are serialized by the driver by passing to the database a special hash containing time.to_f and its timezone. The database takes this value and truncates it to get a precision of a millisecond.
  • When writing your application tests, you have to keep this loss of precision in mind when using == on times. Applying to_i before comparing times is a good workaround to millisecond rounding issues.

If this behavior does not match your expectations, please open an issue on GitHub.