How to get validation messages for all nested records

user_1184904 0
Viewed 322

Given this models:

class Foo < ApplicationRecord
  has_many :bars
  accepts_nested_attributes_for :bars
end

class Bar < ApplicationRecord
  validates :title, presence: true
end

I want to get the validation message for each nested Bar I create, because ...

Foo.create(bars_attributes: [, { title: nil }, { title: "foo" }, { title: nil }])

... results in @errors=[#<ActiveModel::NestedError attribute=bars.title, type=blank, options={}>], but I don't know which records (in this case, records at index 0 and 2) have failed. Is this possible at all?

ruby-on-rails
3 Answers

Break it down. Instead of trying to do everything in one command (which can only give you a success/failure response), try something like this (assumes it's being passed the details of your required Bar records in the params as an Enumerable (i.e. array or hash)).

@foo = foo.create(field_1: foo_params[:field_1], field_2: foo_params[:field_2])
_failed_bar_records = []
foo_params[:bar_data].each do |_bar_data|
  _bar = Bar.new(foo_id: @foo.id, title: _bar_data[:title])
  _failed_bar_records.push(_bar_data[:title]) unless _bar.save
end

Then, you'll have an array _failed_bar_records that contains data about each failed record. You could obviously push more to this array, like the actual error message.

user_114587400

you could dig down to nested record's errors instead of checking the parent record's errors

@problem = Problem.new(problem_params)

@problem.solutions
# [<Solution:0x0000565379c46170 id: nil, description: "a solution", problem_id: nil, ...>,
#  <Solution:0x0000565379cc2248 id: nil, description: "", problem_id: nil, ...>]

@problem.save

@problem.errors
# <ActiveModel::Errors:..
# @base= <Problem:0x0000565379c33890 ...>,
# @errors=[
#  <ActiveModel::NestedError attribute=solutions.description, type=blank, options={}>
# ]>

@problem.solutions.map(&:errors)
# [
#   <ActiveModel::Errors:...
#    @base= <Solution:0x0000565379c46170 ...>,
#    @errors=[]>,
#
#   <ActiveModel::Errors:...
#    @base= <Solution:0x0000565379cc2248 ...>,
#    @errors=[
#     <ActiveModel::Error attribute=description, type=blank, options={}>
#    ]>
# ]
user_122196790

Elaborating on Lam Phan's answer, validation errors for each child are accessible as a property of the child itself.

foo = Foo.create(bars_attributes: [{title: nil},{ title: "foo" }, {title: nil}])
=> #<Foo:0x0000559761e83c50 id: nil, created_at: nil, updated_at: nil>

foo.bars.map(&:errors).map(&:details)
=> [{:title=>[{:error=>:blank}]}, {}, {:title=>[{:error=>:blank}]}]

foo.bars.map(&:errors).map(&:messages)
=> [{:title=>["can't be blank"]}, {}, {:title=>["can't be blank"]}]

On a different, arguably less elegant path, with a custom method for validation, it's possible to cycle on the received nested records, adding an error that registers the index of the failing ones.

class Foo < ApplicationRecord
  has_many :bars
  accepts_nested_attributes_for :bars
  validate :bars_validator

  def bars_validator
    children_valid = bars.map(&:valid?).all?
    bars.each_with_index do |b,i| 
      b.errors.each do |err|
        msg = "#{i}: #{err.attribute} #{err.message}"
        errors.add(:bars, msg, index: i, src: err)
      end
    end
    children_valid
  end
end

The index is then retrieved through errors.details

foo = Foo.create(bars_attributes: [{ title: nil }, { title: "foo" }, { title: nil }])
=> #<Foo:0x00005583f6607a50 id: nil, created_at: nil, updated_at: nil>

foo.errors.details
=>
{:"bars.title"=>[{:error=>:blank}],
 :bars=>
  [{:error=>"0: title can't be blank", :index=>0, :src=>#<ActiveModel::Error attribute=title, type=blank, options={}>},
   {:error=>"2: title can't be blank", :index=>2, :src=>#<ActiveModel::Error attribute=title, type=blank, options={}>}]}
user_37397560
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