In Rails, I'm coding a series of controllers to generate XML. Each time I'm passing a number of properties in to to_xml like:
to_xml(:skip_types => true, :dasherize => false)
Is there a way I can set these as new default properties that will apply whenever to_xml is called in my app so that I don't have to repeat myself?
Are you calling to_xml on a hash or an ActiveRecord model (or something else)?
I am not that you would want to, but you can easily monkey patch to_xml and redefine it to start with those parameters. I would suggest that you make a new method to_default_xml that simply called to_xml with the parameters you wanted
def to_default_xml
self.to_xml(:skip_types => true, :dasherize => false)
end
Update:
Since you want to add this to a couple of ActiveRecord models you could do two things, open up ActiveRecord::base (which is a bit hackish and fragile) or create a module and import it into every model you want to use with it. A little more typing, but much cleaner code.
I would put a class in lib/ that looks something like this:
module DefaultXml
def to_default_xml
self.to_xml(:skip_types => true, :dasherize => false)
end
end
Then in your models:
class MyModel < ActiveRecord::Base
include DefaultXml
end
I put together a plugin to handle default serialization options. Check it out at github.com/laserlemon/dry_serial/tree/master.
class MyModel < ActiveRecord::Base
dry_serial :skip_types => true, :dasherize => false
end
It also has support for multiple serialization styles that can be called like:
#my_model.to_xml(:skinny)
#my_model.to_xml(:fat)
Assuming you're talking about AR's to_xml method and depending on your needs, you could get away with extending the AcitveRecord class by creating a file named: lib\class_extensions.rb
class ActiveRecord::Base
def to_xml_default
self.to_xml(:skip_types => true, :dasherize => false)
end
end
Next, put this in an initializer, so that it's included when Rails starts up:
require 'class_extensions'
Now, you can use it as follows (w/o having to specifically include it in each model):
MyModel.to_xml_default
Related
I'm running into an issue where I'm working with the as_json method, and how to efficiently return the object in JSON AND it's belongs_to object as JSON as well, where the belongs_to object has its own belongs_to object. Code would probably explain it better.
The Not-Working Way
Alert class
class Alert < ActiveRecord::Base
belongs_to :message
# for json rendering
def as_json(options={})
super(:include => :message)
end
end
Message class
def as_json(options={})
super( methods: [:timestamp, :num_photos, :first_photo_url, :tag_names],
include: { camera: { only: [:id, :name] },
position: { only: [:id, :name, :address, :default_threat_level ]},
images: { only: [:id, :photo_url, :is_hidden]} })
end
The problem with this first set up is that when I have an Alert object and call
alert.as_json()
I get all the attributes from Alert and all the attributes from Message, but none of the other attributes from Message that I want, like Camera, Position, etc.
Here's the "It's Working, But Probably Not Proper Design Way"
Alert Class
class Alert < ActiveRecord::Base
belongs_to :message
# for json rendering
def as_json(options={})
super().merge(:message => message.as_json)
end
end
Messages Class
# for json rendering
def as_json(options={})
super( methods: [:timestamp, :num_photos, :first_photo_url, :tag_names])
.merge(:camera => camera.as_json)
.merge(:position => position.as_json)
.merge(:images => images.as_json)
end
In this 2nd setup, I get all of Messages's nested attributes like I want.
My question, am I missing some Rails Convention to do this properly? It seems like there would/should be an easier way.
The best answer for me was using serializable_hash. #kikito touched on this in his comment, but there was a typo that prevented it from working. It's not serialized_hash, it's serializable_hash.
Literally just find + replace as_json with serializable_hash and this bug goes away. (It's still not fixed in today's Rails 4.0.2). You also get the benefit of having an easier time implementing an XML API later (some people still use those!).
Which version of Rails are you using? This is a known bug in older versions of Rails, supposedly fixed with this pull request. Your syntax looks right to me, so perhaps this is your problem?
As an aside, you may also want to checkout the new active_model_serializers from Jose Valim (Rails core member). It may at least enable you to work around your issue in a more elegant manner.
I would recommend you to take a look at RABL (stands for Ruby API Builder Language) gem (railscast, github). It offers you a DSL for defining the structure of your JSON (and also XML) response in templates (like Haml or CoffeeScript does). It also supports partials.
I would like to enhance existing class using instance_eval. There original definition contains validation, which require presence of certain fields, ie:
class Dummy < ActiveRecord::Base
validates :field, :presence => true
end
Now I want to change that to optional using instance_eval (or any other method, really):
Dummy.instance_eval do
...
end
What would be the proper syntax to remove the validation, so the field is optional. I would rather do this directly on the model layer, instead doing weird hacks in controllers or views. The use of instance_eval is not really required, but as far as I know, this is generally the best way to enhance classes in Rails.
Edit #1
In general - the original class is part of the gem and I don't want to fork it, nor tie to specific release. The general cause is not really important. Simply editing the original model has far worse consequences than monkey patching.
I found a solution, not sure how solid it is, but it works well in my case. #aVenger was actually close with his answer. It's just that the _validators accessor contains only information used for reflection, but not the actual validator callbacks! They are contained in the _validate_callbacks accessor, not to be confused with _validations_callbacks.
Dummy.class_eval do
_validators.reject!{ |key, _| key == :field }
_validate_callbacks.reject! do |callback|
callback.raw_filter.attributes == [:field]
end
end
This will remove all validators for :field. If you want to be more precise, you can reject the specific validator for _validators which is the same as the raw_filter accessor of validate callbacks.
I think this is the most actual solution at this moment (I'm using rails 4.1.6):
# Common ninja
class Ninja < ActiveRecord::Base
validates :name, :martial_art, presence: true
end
# Wow! He has no martial skills
Ninja.class_eval do
_validators[:martial_art]
.find { |v| v.is_a? ActiveRecord::Validations::PresenceValidator }
.attributes
.delete(:martial_art)
end
Easest way to remove all validations:
clear_validators!
As I was trying to do this to remove the phone validation from the spree Address model, below is the code I got to work. I added the type check for callback.raw_filter because I only wanted to remove the presence validator on the phone field. I also had to add it because it would fail when trying to run against one of the other validators specified in the Spree::Address model that did not have an 'attributes' key for callback.raw_filter, thus an exception was thrown.
Spree::Address.class_eval do
# Remove the requirement on :phone being present.
_validators.reject!{ |key, _| key == :phone }
_validate_callbacks.each do |callback|
callback.raw_filter.attributes.delete :phone if callback.raw_filter.is_a?(ActiveModel::Validations::PresenceValidator)
end
end
I had a similar problem and was able to get past it using:
class MyModel << Dummy
# erase the validations defined in the plugin/gem because they interfere with our own
Dummy.reset_callbacks(:validate)
...
end
This is under Rails 3.0. The caveat: It does remove ALL validations, so if there are others you want to keep you could try Dummy.skip_callback(...), but I could not figure out the right incantation of arguments to make that work.
One solution is to extend validates :
#no need of instance_eval just open the class
class Dummy < ActiveRecord::Base
#validates :field, :presence => true
def self.validates(*attributes)
if attributes.first == :field #=> add condition on option if necessary
return # don't validate
else
super(*attributes) #let normal behavior take over
end
end
end
And no that's not monkey-patching but extending or decorating a behavior. Rails 3.1 is built on the idea of "multi- inheritance" with module inclusion, specifically to allow this kind agility.
update #2
One caveat is you must load the class with the redefined validates method before the gem containing the call to validates. To do so, require the file in config/application.rb after require "rails/all" as suggested in the railsguides. Something like that :
require File.expand_path('../boot', __FILE__)
require 'rails/all' # this where rails (including active_record) is loaded
require File.expand_path('../dummy' __FILE__) #or wherever you want it
#this is where the gems are loaded...
# the most important is that active_record is loaded before dummy but...
# not after the gem containing the call to validate :field
if defined?(Bundler)
Bundler.require *Rails.groups(:assets => %w(development test))
end
Hope it works now!
Answer by aVenger has problems when you declare validations of more than one attribute in a line:
validates :name, :message, :presence => true
That's because this line creates a raw_filter with more than one attribute in attributes filter:
Model.send(:_validate_callbacks)
=> [#<ActiveSupport::Callbacks::Callback:0xa350da4 #klass=Model(...), ... , #raw_filter=#<ActiveModel::Validations::PresenceValidator:0x9da7470 #attributes=[:name, :message], #options={}>, #filter="_callback_before_75", #compiled_options="true", #callback_id=76>]
We have to delete the desired attribute from that array and reject the callbacks without attributes
Dummy.class_eval do
_validators.reject!{ |key, _| key == :field }
_validate_callbacks.each do |callback|
callback.raw_filter.attributes.delete :field
end
_validate_callbacks.reject! do |callback|
callback.raw_filter.attributes.empty? ||
callback.raw_filter.attributes == [:field]
end
end
I have this working on a Rails 3.2.11 app.
For rails 4.2 (~ 5.0) it can be used the following module with a method:
module ValidationCancel
def cancel_validates *attributes
attributes.select {|v| Symbol === v }.each do |attr|
self._validators.delete( attr )
self._validate_callbacks.select do |callback|
callback.raw_filter.try( :attributes ) == [ attr ] ;end
.each do |vc|
self._validate_callbacks.delete( vc ) ;end ;end ;end ;end
Note: Since the filtern can be a symbol of an association, or a specific validator, so we have to use #try.
Then we can use rails-friendly form in a class declaration:
class Dummy
extend ValidationCancel
cancel_validates :field ;end
Note: since removal of the validator is affecting to the whole class and its descendants globally, it is not recommended to use it to remove validations in such way, instead add if clause for the specific rule as follows:
module ValidationCancel
def cancel_validates *attributes
this = self
attributes.select {|v| Symbol === v }.each do |attr|
self._validate_callbacks.select do |callback|
callback.raw_filter.try( :attributes ) == [ attr ] ;end
.each do |vc|
ifs = vc.instance_variable_get( :#if )
ifs << proc { ! self.is_a?( this ) } ;end ;end ;end ;end
This restricts execution of the validation callback for the specified class and its descendants.
If you doesn't want to make any changes in Parent class then first clear all validations in child class and copy all required validation from parent class to child class
class Dummy < ActiveRecord::Base
validates :property, presence: true
validates :value, length: { maximum: 255 }
end
And override it in child class
Dummy.class_eval do
clear_validators!
validates :property, presence: true
end
If you really want to do this then here would be a good place to start digging: https://github.com/rails/rails/blob/ed7614aa7de2eaeba16c9af11cf09b4fd7ed6819/activemodel/lib/active_model/validations/validates.rb#L82
However, to be honest, inside of ActiveModel is not where I'd be poking with a stick.
If you can edit the constraint on the original model to put an :if => :some_function on it, you can easily change the behavior of the function it calls to return false. I tested this and it works pretty easily:
class Foo < ActiveRecord::Base
validates :field, :presence => true, :if => :stuff
attr_accessor :field
def stuff
return true;
end
end
and then somewhere else:
Foo.class_eval {
def stuff
false
end
}
Why not use #dummy.save_without_validation method to skip validations altogether? I prefer do something like this:
if #dummy.valid?
#dummy.save # no problem saving a valid record
else
if #dummy.errors.size == 1 and #dummy.errors.on(:field)
# skip validations b/c we have exactly one error and it is the validation that we want to skip
#dummy.save_without_validation
end
end
You could put this code in your model or in the controller, depending on your needs.
In Rails 4.1,
I was able to do _validate_callbacks.clear. In my case, I wanted all the validations for a gem removed, so I could create my own. I did this in a module that was patched into the class.
Module #Name
extend ActiveSupport::Concern
included do
_validate_callbacks.clear
#add your own validations now
end
end
Wanted to add that, if you're trying to clear validations on a instance of your Model (not the entire model class), don't do my_dummy._validate_callbacks.clear, as that will clear validations on every instance (and future instance) of your Dummy model class.
For just the instance (and if you wanted to reinstate the validations later), try the following:
Create a copy of the validate callbacks (if you want to reinstate later):
my_dummy_validate_callbacks = my_dummy._validate_callbacks.clone
Set the validate callbacks on your instance to empty:
my_dummy._validate_callbacks = {}
Do what you want on my_dummy validation free!
Reinstate the callbacks: my_dummy._validate_callbacks = my_dummy_validate_callbacks
I'd have to look more into the code and help, but I'm thining it might be possible to inspect the list of validators of the class, and then modify the entry for the validation you want to change to add in an :if => :some_function conditional to it.
You'll need to do it only once for production (so it can be put inside an initializer, but for development you'll need to put it in the model, or somewhere else that will get loaded each time the corresponding model is (perhaps an observer?).
(I'll edit the answer with more information as I come to research it.)
Every Rails validator, pre-defined or custom, is an object, and is expected to respond to #validate(record) method. You can monkey patch or stub this method.
# MyModel.validators_on(:attr1, :attr2, ...) is also useful
validator = MyModel.validators.detect do |v|
validator_i_am_looking_for?(v)
end
def validator.validate(*_)
true
end
# In RSpec you can also consider:
allow(validator).to receive(:validate).and_return(true)
Tested in Rails 5.1.
Don't do this unless you understand what you're doing ;)
This does not directly answer the question but here's an option you should consider in such a situation: instead of disabling validation, you could set the required fields in a before_validation hook.
Since you don't need those required fields, set them with some dummy data that satisfies the validation and forget about them.
No ugly monkey patching.
Assuming the original implementation of Dummy is defined in an engine there is a nasty hack that will do what you want. Define Dummy in your application to keep the original implementation of Dummy from being auto-loaded. Then load the source to Dummy and remove the line that does the validation. Eval the modified source.
Put the following in your app/models/dummy.rb
class Dummy < ActiveRecord::Base
end
# Replace DummyPlugin with name of engine
engine = Rails::Application::Railties.engines.find { |e| e.class == DummyPlugin::Engine }
dummy_source = File.read File.join(engine.config.root, "app", "models", "dummy.rb")
dummy_source = dummy_source.gsub(/validates :field, :presence => true.*/, "")
eval dummy_source
If it is regular gem instead of an engine the same concept would apply, just would need to load the source for Dummy from the gem root instead of the engine root.
I'm using Mongoid and when I .update_attributes on a model that has a references_one using params[:model_name] I get the error...
#model.update_attributes(params[:model_name])
undefined method `associations' for "...":String
I understand why this is happening. Mongoid is trying to map that .association_name to the string value in the params hash when what it wants is a reference to another Mongoid::Document. That I get.
What I'd like to know is if there is a global way to fix this. For the moment I've gotten around this issue by doing something like the following...
model_params = params[:model_name]
if model_params.has_key? :relationship
model_params[:relationship] = RelatedModel.first(:conditions => { :_id => model_params[:relationship] })
end
This works but I'd rather have a fix that fixes it every time so that I'm not manually mapping the related model every time I do an update. That would defiantly be a violation of DRY.
Here's sample module that you could include in all your models
module MyAppBase
def my_update_attributes(model_params,related_model)
if model_params.has_key? :relationship
model_params[:relationship] = related_model.first(:conditions => { :_id => model_params[:relationship] })
end
self.update_attributes(model_params)
end
end
#include it in your model classes
class MyModel < ActiveRecord::Base
include MyAppBase
#normal model code
end
I have an ActiveRecord model whose fields mostly come from the database. There are additional attributes, which come from a nested serialised blob of stuff. This has been done so that I can use these attributes from forms without having to jump through hoops (or so I thought in the beginning, anyway) while allowing forwards and backwards compatibility without having to write complicated migrations.
Basically I am doing this:
class Licence < ActiveRecord::Base
attr_accessor :load_worker_count
strip_attributes!
validates_numericality_of :load_worker_count,
:greater_than => 2, :allow_nil => true, :allow_blank => true
before_save :serialise_fields_into_properties
def serialise_fields_into_properties
...
end
def after_initialize
...
end
...
end
The problem I noticed was that I can't get empty values in :load_worker_count to be accepted by the validator, because:
If I omit :allow_blank, it fails validation complaining about it being blank
If I put in :allow_blank, it converts the blank to 0, which when fails on the :greater_than => 2
In tracking down why these blank values are getting to the validation stage in the first place, I discovered the root of the problem: strip_attributes! only affects actual attributes, as returned by the attributes method. So the values which should be nil at time of validation are not. So it feels like the root cause is that the synthetic attributes I added in aren't seen when setting which attributes to strip, so therefore I ask:
Is there a proper way of creating synthetic attributes which are recognised as proper attributes by other code which integrates with ActiveRecord?
I assume you are talking of the strip_attributes plugin; looking at the code, it uses the method attributes, defined in active_record/base.rb, which uses #attributes, which is initialized (in initialize) as #attributes = attributes_from_column_definition.
Maybe it's possible to hack ActiveRecord::Base somehow, but it would be a hard work: #attributes is also used when getting/putting stuff from/to db, so you would have to do a lot of hacking.
There's a much simpler solution:
before_validate :serialise_fields_into_properties
...
def serialise_fields_into_properties
if load_worker_count.respond_to? :strip
load_worker_count = load_worker_count.blank? ? nil : load_worker_count.strip
end
...
end
After all, this is what strip_attributes! does.
Wouldn't it be easier to just use Rails' serialize macro here?
class License < ActiveRecord::Base
serialize :special_attributes
end
Now you can assign a hash or array or whatever you need to special_attributes and Rails will serialize it a text field in the database.
license = License.new
license.special_attributes = { :beer => true, :water => false }
This will keep your code clean and you don't have to worry about serializing/deserializing attributes yourself.
I want to create a Rails (2.1 and 2.2) model with ActiveRecord validations, but without a database table. What is the most widely used approach? I've found some plugins that claim to offer this functionality, but many of them don't appear to be widely used or maintained. What does the community recommend I do? Right now I am leaning toward coming up with my own solution based on this blog post.
There is a better way to do this in Rails 3: http://railscasts.com/episodes/219-active-model
This is an approach I have used in the past:
In app/models/tableless.rb
class Tableless < ActiveRecord::Base
def self.columns
#columns ||= [];
end
def self.column(name, sql_type = nil, default = nil, null = true)
columns << ActiveRecord::ConnectionAdapters::Column.new(name.to_s, default,
sql_type.to_s, null)
end
# Override the save method to prevent exceptions.
def save(validate = true)
validate ? valid? : true
end
end
In app/models/foo.rb
class Foo < Tableless
column :bar, :string
validates_presence_of :bar
end
In script/console
Loading development environment (Rails 2.2.2)
>> foo = Foo.new
=> #<Foo bar: nil>
>> foo.valid?
=> false
>> foo.errors
=> #<ActiveRecord::Errors:0x235b270 #errors={"bar"=>["can't be blank"]}, #base=#<Foo bar: nil>>
There is easier way now:
class Model
include ActiveModel::Model
attr_accessor :var
validates :var, presence: true
end
ActiveModel::Model code:
module ActiveModel
module Model
def self.included(base)
base.class_eval do
extend ActiveModel::Naming
extend ActiveModel::Translation
include ActiveModel::Validations
include ActiveModel::Conversion
end
end
def initialize(params={})
params.each do |attr, value|
self.public_send("#{attr}=", value)
end if params
end
def persisted?
false
end
end
end
http://api.rubyonrails.org/classes/ActiveModel/Model.html
I think the blog post you are linking is the best way to go. I would only suggest moving the stubbed out methods into a module not to pollute your code.
just create a new file ending in ".rb" following the conventions you're used to (singular for file name and class name, underscored for file name, camel case for class name) on your "models/" directory. The key here is to not inherit your model from ActiveRecord (because it is AR that gives you the database functionality).
e.g.: for a new model for cars, create a file called "car.rb" in your models/ directory and inside your model:
class Car
# here goes all your model's stuff
end
edit: btw, if you want attributes on your class, you can use here everything you use on ruby, just add a couple lines using "attr_accessor":
class Car
attr_accessor :wheels # this will create for you the reader and writer for this attribute
attr_accessor :doors # ya, this will do the same
# here goes all your model's stuff
end
edit #2: after reading Mike's comment, I'd tell you to go his way if you want all of the ActiveRecord's functionality but no table on the database. If you just want an ordinary Ruby class, maybe you'll find this solution better ;)
For the sake of completeness:
Rails now (at V5) has a handy module you can include:
include ActiveModel::Model
This allows you to initialise with a hash, and use validations amongst other things.
Full documentation is here.
There's a screencast about non-Active Record model, made up by Ryan Bates. A good place to start from.
Just in case you did not already watch it.
I have built a quick Mixin to handle this, as per John Topley's suggestion.
http://github.com/willrjmarshall/Tableless
What about marking the class as abstract?
class Car < ActiveRecord::Base
self.abstract = true
end
this will tell rails that the Car class has no corresponding table.
[edit]
this won't really help you if you'll need to do something like:
my_car = Car.new
Use the Validatable gem. As you say, there are AR-based solutions, but they tend to be brittle.
http://validatable.rubyforge.org/
Anybody has ever tried to include ActiveRecord::Validations and ActiveRecord::Validations::ClassMethods in a non-Active Record class and see what happens when trying to setup validators ?
I'm sure there are plenty of dependencies between the validation framework and ActiveRecord itself. But you may succeed in getting rid of those dependencies by forking your own validation framework from the AR validation framework.
Just an idea.
Update: oopps, this is more or less what's suggested in the post linked with your question. Sorry for the disturbance.
Do like Tiago Pinto said and just don't have your model inherit from ActiveRecord::Base. It'll just be a regular Ruby class that you stick in a file in your app/models/ directory. If none of your models have tables and you're not using a database or ActiveRecord at all in your app, be sure to modify your environment.rb file to have the following line:
config.frameworks -= [:active_record]
This should be within the Rails::Initializer.run do |config| block.
You ought to checkout the PassiveRecord plugin. It gives you an ActiveRecord-like interface for non-database models. It's simple, and less hassle than fighting ActiveRecord.
We're using PassiveRecord in combination with the Validatable gem to get the OP's desired behaviour.