I'm receiving a JSON object and nested array via a Rails 4 api with params like so:
{
"token" => "123"
"lessons" => [
{
"token_id" => "j12l3n123",
"attr_1" => "hello",
"attr_2" = "is it me you're looking for"
},
{
"token_id" => "j12l",
"attr_1" => "Nope",
"attr_3" = "You're not."
}
]
}
And I have a controller like so:
def update_all
#fetch collection with one db hit
token_ids = params[:lessons].map{|l| l[:token_id]}
#lessons = Lesson.where(token_id: token_ids)
params[:lessons].each do |l|
lesson = #lessons.detect { |lesson| lesson.token_id == l[:token_id] }
# How do I update the record with strong params?
lesson.update_attributes(lesson_params)
end
end
private
def lesson_params
params.permit(
:attr_1,
:attr_2,
:attr_3
)
end
How do i update each record with the right object in the array, and use strong parameters to do so?
def update_all
lesson_params.each do |l|
lesson = Lesson.where(token_id: l[:token_id]).first
lesson.update_attributes(l)
end
end
private
def lesson_params
params.require(:lessons).map do |l|
ActionController::Parameters.new(l.to_hash).permit(
:attr_1,
:attr_2,
:attr_3
)
end
end
def lesson_params
params.permit(:token, lessons: [:token_id, :attr_1, :attr_2, :attr_3 ])
end
in Controller something like following
def update_all
lesson_params[:lessons].each do |lesson_param|
lesson = Lesson.find(lesson_param[:token_id])
lesson.update_attributes(lesson_param)
end
end
Related
Is there a clean way to destroy all children NOT included in array of passed nested attributes?
Now I have to find difference between actual children and nested attributes array, and then set _destroy: true for each, but it looks ugly.
class Report < ActiveRecord::Base
has_many :consumed_products
accepts_nested_attributes_for :consumed_products, allow_destroy: true
def nested_attributes_destroy_difference(attrs)
combined = attrs.reduce({}) {|h,pairs| pairs.each {|k,v| (h[k] ||= []) << v}; h}
diff = consumed_products - consumed_products.where(combined)
attrs + diff.map{|i| {id: i.id, _destroy: true} }
end
end
class Api::V2::ReportsController < Api::V2::BaseController
def update
report = Report.find(params[:id])
report_attributes = report_params
if params[:consumed_products]
report_attributes.merge!(consumed_products_attributes: report.nested_attributes_destroy_difference(consumed_products_attributes))
end
report.assign_attributes report_attributes
end
private
def consumed_products_attributes
params[:consumed_products].map do |p|
{product_id: p[:id], product_measure_id: p[:measure_id], quantity: p[:quantity]}
end
end
def report_params
#...
end
end
I'm learning Ruby on Rails and got curious how the params method works. I understand what it does, but how?
Is there a built-in method that takes a hash string like so
"cat[name]"
and translates it to
{ :cat => { :name => <assigned_value> } }
?
I have attempted to write the params method myself but am not sure how to write this functionality in ruby.
The GET parameters are set from ActionDispatch::Request#GET, which extends Rack::Request#GET, which uses Rack::QueryParser#parse_nested_query.
The POST parameters are set from ActionDispatch::Request#POST, which extends Rack::Request#POST, which uses Rack::Multipart#parse_multipart. That splays through several more files in lib/rack/multipart.
Here is a reproduction of the functionality of the method (note: this is NOT how the method works). Helper methods of interest: #array_to_hash and #handle_nested_hash_array
require 'uri'
class Params
def initialize(req, route_params = {})
#params = {}
route_params.keys.each do |key|
handle_nested_hash_array([{key => route_params[key]}])
end
parse_www_encoded_form(req.query_string) if req.query_string
parse_www_encoded_form(req.body) if req.body
end
def [](key)
#params[key.to_sym] || #params[key.to_s]
end
def to_s
#params.to_s
end
class AttributeNotFoundError < ArgumentError; end;
private
def parse_www_encoded_form(www_encoded_form)
params_array = URI::decode_www_form(www_encoded_form).map do |k, v|
[parse_key(k), v]
end
params_array.map! do |sub_array|
array_to_hash(sub_array.flatten)
end
handle_nested_hash_array(params_array)
end
def handle_nested_hash_array(params_array)
params_array.each do |working_hash|
params = #params
while true
if params.keys.include?(working_hash.keys[0])
params = params[working_hash.keys[0]]
working_hash = working_hash[working_hash.keys[0]]
else
break
end
break if !working_hash.values[0].is_a?(Hash)
break if !params.values[0].is_a?(Hash)
end
params.merge!(working_hash)
end
end
def array_to_hash(params_array)
return params_array.join if params_array.length == 1
hash = {}
hash[params_array[0]] = array_to_hash(params_array.drop(1))
hash
end
def parse_key(key)
key.split(/\]\[|\[|\]/)
end
end
In my rails app i defined a specific JSON-Format in my model:
def as_json(options={})
{
:id => self.id,
:name => self.name + ", " + self.forname
}
end
And in the controller i simply call:
format.json { render json: #patients}
So now im trying to define another JSON-Format for a different action but i dont know how?
How do i have to define another as_json or how can i pass variables to as_json? Thanks
A very ugly method but you can refactor it for better readability:
def as_json(options={})
if options.empty?
{ :id => self.id, :name => self.name + ", " + self.forname }
else
if options[:include_contact_name].present?
return { id: self.id, contact_name: self.contact.name }
end
end
end
Okay, I should give you a better piece of code, here it is:
def as_json(options = {})
if options.empty?
self.default_json
else
json = self.default_json
json.merge!({ contact: { name: contact.name } }) if options[:include_contact].present?
json.merge!({ admin: self.is_admin? }) if options[:display_if_admin].present?
json.merge!({ name: self.name, forname: self.forname }) if options[:split_name].present?
# etc etc etc.
return json
end
end
def default_json
{ :id => self.id, :name => "#{self.name}, #{self.forname}" }
end
Usage:
format.json { render json: #patients.as_json(include_contact: true) }
By defining hash structure by 'as_json' method, in respective model class i.e User model in (Example 1), it becomes the default hash stucture for active record(i.e., user) in json format. It cannot be overridden by any inline definitions as defined in Example: 2
Example 1:
class User < ActiveRecord::Base
.....
def as_json(options={})
super(only: [:id, :name, :email])
end
end
Example: 2
class UserController < ApplicationController
....
def create
user = User.new(params[:user])
user.save
render json: user.as_json( only: [:id, :name] )
end
end
Therefore, in this example when create action is executed 'user' is returned in ("only: [:id, :name, :email]") format not as ("only: [:id, :name]")
So, options = {} are passed to as_json method to specifiy different format for different methods.
Best Practice, is to define hash structure as constant and call it everwhere it is needed
For Example
Ex: models/user.rb
Here, constant is defined in model class
class User < ActiveRecord::Base
...
...
DEFAULT_USER_FORMAT = { only: [:id, :name, :email] }
CUSTOM_USER_FORMAT = { only: [:id, :name] }
end
Ex: controllers/user.rb
class UserController < ApplicationController
...
def create
...
render json: user.as_json(User::DEFAULT_USER_FORMAT)
end
def edit
...
render json: user.as_json(User::CUSTOM_USER_FORMAT)
end
end
Cool!
Looking for gem or at least idea how to approach this problem, the ones I have are not exactly elegant :)
Idea is simple I would like to map hashes such as:
{ :name => 'foo',
:age => 15,
:job => {
:job_name => 'bar',
:position => 'something'
...
}
}
To objects of classes (with flat member structure) or Struct such as:
class Person {
#name
#age
#job_name
...
}
Thanks all.
Assuming that you can be certain sub-entry keys won't conflict with containing entry keys, here's some code that should work...
require 'ostruct'
def flatten_hash(hash)
hash = hash.dup
hash.entries.each do |k,v|
next unless v.is_a?(Hash)
v = flatten_hash(v)
hash.delete(k)
hash.merge! v
end
hash
end
def flat_struct_from_hash(hash)
hash = flatten_hash(hash)
OpenStruct.new(hash)
end
Solution that I used it solves problem with same key names but it does not give flat class structure. Somebody might find this handy just keep in mind that values with reserved names such as id, type need to be handled.
require 'ostruct'
def to_open_struct(element)
struct = OpenStruct.new
element.each do |k,v|
value = Hash === v ? to_open_struct(v) : v
eval("object.#{k}=value")
end
return struct
end
An alternate answer where you know the keys before hand
class Job
attr_accessor :job_name, :position
def initialize(params = {})
self.job_name = params.fetch(:job_name, nil)
self.position = params.fetch(:position, nil)
end
end
class Person
attr_accessor :name, :age, :job
def initialize(params = {})
self.name = params.fetch(:name, nil)
self.age = params.fetch(:age, nil)
self.job = Job.new(params.fetch(:job, {}))
end
end
hash = { :name => 'foo', :age => 1, :job => { :job_name => 'bar', :position => 'soetmhing' }}
p = Person.new(hash)
p.name
==> "foo"
p.job
==> #<Job:0x96cacd8 #job_name="bar", #position="soetmhing">
p.job.name
==> "bar"
I am using Ruby on Rails 3 and I would like to inizialize an ActiveRecord Tableless Model.
In my model I have:
class Account < ActiveRecord::Base
# The following ActiveRecord Tableless Model statement is from http://codetunes.com/2008/07/20/tableless-models-in-rails/
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
attr_reader :id,
:firstname,
:lastname,
def initialize(attributes = {})
#id = attributes[:id]
#firstname = attributes[:firstname]
#lastname = attributes[:lastname]
end
end
If in a controller, for example in the application_controller.rb file, I do:
#new_account = Account.new({:id => "1", :firstname => "Test name", :lastname => "Test lastname"})
a debug\inspect output of the #new_account variable is
"#<Account >"
Why? How I should inizialize properly that ActiveRecord Tableless Model and make it to work?
According to that blog post it would have to look like this:
class Account < ActiveRecord::Base
class_inheritable_accessor :columns
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
column :id, :integer
column :firstname, :string
column :lastname, :string
end
And then:
#new_account = Account.new({:id => "1", :firstname => "Test name", :lastname => "Test lastname"})
Did you already try it like that?
I my view, you don't need to extend ActiveRecord::Base class.
You can write your own model class something like this
# models/letter.rb
class Letter
attr_reader :char
def self.all
('A'..'Z').map { |c| new(c) }
end
def self.find(param)
all.detect { |l| l.to_param == param } || raise(ActiveRecord::RecordNotFound)
end
def initialize(char)
#char = char
end
def to_param
#char.downcase
end
def products
Product.find(:all, :conditions => ["name LIKE ?", #char + '%'], :order => "name")
end
end
# letters_controller.rb
def index
#letters = Letter.all
end
def show
#letter = Letter.find(params[:id])
end
I hope it will help you.
Reference: http://railscasts.com/episodes/121-non-active-record-model