Rails dynamically create model and use it - ruby-on-rails

I am creating a model whose name is the input argument in a rake task. After the rake task, I wish to use the model to insert data.
So for example, I call my rake task with input Apple and the model Apple is created. Then I wish to do Apple.insert_all([{name: x},{name: y}...]) in another rake task but I get NameError: uninitialized constant Apple
Here's a better picture of the flow of what I'm doing
Rake::Task["create:fruit"].invoke("Apple") # create model here
Rake::Task["create:insert"].invoke("Apple") # insert data here but getting error
This is how I process the input in the second rake task:
task :insert, [:name] do |t, args|
fruit = args.name
fruit.classify.constantize.insert_all(xxx)
end
Any suggestions for how to go about this?

I created a new project and tried your code. I think the problem is in this line
fruit.classify.constantize.insert_all(xxx)
The code bellow works and create new records. I use a simple rake command to run it.
create.rake file
namespace :create do
desc "TODO"
task :insert, [:name] do |t, args|
klass = Object.const_get(args.name)
klass.create([{name: 'x'},{name: 'y'}])
p klass.count # testing new records have been saved
end
end
Rakefile file
require File.expand_path('../config/application', __FILE__)
Rails.application.load_tasks
task :default do
Rake::Task["create:insert"].invoke("Apple")
end

Related

Cannot load namespaced model when invoking rake task

I got a rake task which invokes other rake tasks, so my development data can be easily reset.
the first rake task (lib/tasks/populate.rake)
# Rake task to populate development database with test data
# Run it with "rake db:populate"
namespace :db do
desc 'Erase and fill database'
task populate: :environment do
...
Rake::Task['test_data:create_company_plans'].invoke
Rake::Task['test_data:create_companies'].invoke
Rake::Task['test_data:create_users'].invoke
...
end
end
the second rake task (lib/tasks/populate_sub_scripts/create_company_plans.rake)
namespace :test_data do
desc 'Create Company Plans'
task create_company_plans: :environment do
Company::ProfilePlan.create!(name: 'Basic', trial_period_days: 30, price_monthly_cents: 4000)
Company::ProfilePlan.create!(name: 'Professional', trial_period_days: 30, price_monthly_cents: 27_500)
Company::ProfilePlan.create!(name: 'Enterprise', trial_period_days: 30, price_monthly_cents: 78_500)
end
end
when I run bin/rake db:populate then i get this error
rake aborted! LoadError: Unable to autoload constant
Company::ProfilePlan, expected
/home/.../app/models/company/profile_plan.rb to define it
but when I run the second rake task independently it works well.
The model (path: /home/.../app/models/company/profile_plan.rb)
class Company::ProfilePlan < ActiveRecord::Base
# == Constants ============================================================
# == Attributes ===========================================================
# == Extensions ===========================================================
monetize :price_monthly_cents
# == Relationships ========================================================
has_many :profile_subscriptions
# == Validations ==========================================================
# == Scopes ===============================================================
# == Callbacks ============================================================
# == Class Methods ========================================================
# == Instance Methods =====================================================
end
Rails 5.0.1
Ruby 2.4.0
The App was just upgraded from 4.2 to 5
It works when I require the whole path:
require "#{Rails.root}/app/models/company/profile_plan.rb"
But this seems strange to me, because in the error message rails has the correct path to the Model. Does someone know why I have to require the file when invoked from another rake task?
Thank you very much
Well, it seems that rake doesn't eager load, so when you call the create_company_plans.rake alone it loads the referred objects, however when you invoke it from another rake, it doesn't know you will need them and so they are not loaded.
You can take a look at this other QA which was similar to yours.
I think maybe you don't need to require the whole path, just:
require 'models/company/profile_plan'
From what I understand, you can probably overcome the problem by reenable ing and then revoke ing the task as given below. Pardon me if this doesn't work.
['test_data:create_company_plans', 'test_data:create_companies'].each do |task|
Rake::Task[task].reenable
Rake::Task[task].invoke
end
There is more info on this stackoverflow question how-to-run-rake-tasks-from-within-rake-tasks .

How to fix "uninitialized constant" in a Rake task

I have a problem when I do:
namespace :xaaron do
task :get_roles do
roles = Xaaron::Role.all
puts roles
end
task :get_role, [:name] do |t, args|
role = Xaaron::Role.find(args[:name].parameterize)
puts role
end
end
The first task will work fine. I can even add binding.pry and run Xaaron::Role and get information about Roles back. But the second task fails with:
NameError: uninitialized constant Xaaron::Role
I run each task in my main app because these tasks are inside an engine, using:
bin/rake xaaron:get_roles` and `bin/rake xaaron:get_role
I can run bin/rails c in the main application that uses the engine and run Xaaron::Role and get information about Roles table.
Why is the second one failing but the first one is not? Is there scoping with arguments?
I'm not sure why either works, but if this is Rails and those are Rails models, your tasks should depend on the environment:
task :get_roles => [ :environment ] do
By depending on the :environment task, it first loads Rails.
Also see: What's the 'environment' task in Rake?.
You can also run a Rake task as
bundle exec rake environment xaaron:get_role
This will load the Rails environment first.
I kept getting uninitialized constant errors for a Rake task, even after depending on :environment and running with bundle exec.
The issue was that I was making a Rake::TestTask and, even though the Rake task had access to all constants, the test files themselves did not have access to constants.
The solution was to add this line to the top of my test file:
require_relative '../config/environment'
This is the Rake task:
require "rake/testtask"
Rake::TestTask.new(:test) do |t|
t.libs << "test"
t.libs << "lib"
t.test_files = FileList["test/**/test_*.rb"]
end
To add, as of Ruby 1.9 and above, you can use this hash syntax:
namespace :xaaron do
desc "Rake task to get roles"
task get_roles: :environment do
roles = Xaaron::Role.all
puts roles
end
#####
end
And then you can run the command below to run the Rake task:
rake xaaron:get_roles
or
bundle exec rake xaaron:get_roles

How to import Model into a custom rake task?

In my lib/tasks folder I added a new .rake file.
In the rake task, I am doing this:
p = Post.new( ....)
p.save!
When I run my task, I get the error:
rake aborted!
uninitialized constant Post
What do I have to do to import my Post model?
I'm thinking you're probably missing the environment declaration. This is necessary in order for Rake to know about your Rails environment. Your rake task call should look something like this:
task :my_rake_task => [:environment] do
# Your code here
end
Let me know if that solves the problem!
You want to make the task dependent on the rails environment. You can do so by specifying the => :environment after the task declaration as such:
namespace :my_task do
desc "an example task"
task :create_post => :environment do
Post.new .... # the rest of the implementation
end
end

How do I access one of my models from within a ruby script in the /lib/ folder in my Rails 3 app?

I tried putting my script in a class that inherited from my model, like so:
class ScriptName < MyModel
But when I ran rake my_script at the command-line, I got this error:
rake aborted!
uninitialized constant MyModel
What am I doing wrong?
Also, should I name my file my_script.rb or my_script.rake?
Just require the file. I do this in one of my rake tasks (which I name my_script.rake)
require "#{Rails.root.to_s}/app/models/my_model.rb"
Here's a full example
# lib/tasks/my_script.rake
require "#{Rails.root.to_s}/app/models/video.rb"
class Vid2 < Video
def self.say_hello
"Hello I am vid2"
end
end
namespace :stuff do
desc "hello"
task :hello => :environment do
puts "saying hello..."
puts Vid2.say_hello
puts "Finished!"
end
end
But a better design is to have the rake task simply call a helper method. The benefits are that it's easier to scan the available rake tasks, easier to debug, and the code the rake task runs becomes very testable. You could add a rake_helper_spec.rb file for example.
# /lib/rake_helper.rb
class Vid2 < Video
def self.say_hello
"Hello I am vid2"
end
end
# lib/tasks/myscript.rake
namespace :stuff do
desc "hello"
task :hello => :environment do
Vid2.say_hello
end
end
All I had to do to get this to work was put my requires above the task specification, and then just declare the :environment flag like so:
task :my_script => :environment do
#some code here
end
Just by doing that, gave me access to all my models. I didn't need to require 'active_record' or even require my model.
Just specified environment and all my models were accessible.
I was also having a problem with Nokogiri, all I did was removed it from the top of my file as a require and added it to my Gemfile.

Create a script or task to modify database

I need to create a script that imports data from a file system source. How do I do that?
I already tried to create a rake task but there the models are not loaded. How do I get the whole rails environment into my task?
desc 'Do stuff with models'
task :do_stuff => :environment do
1000.times.each do |i|
Model.create :name => "model number #{i}"
end
end
You declare :environment as a dependency of your rake task. This loads up rails and all of your app code before it runs.

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