Rails Edit/Update action not working with nested models (has_many :through)

Question

The edit/update actions doesn't work.

I have three models:

document.rb

belongs_to :languages
has_many :configuration_documents
has_many :document_catalogs, through: :configuration_documents

accepts_nested_attributes_for :document_catalogs
accepts_nested_attributes_for :configuration_documents

document_catalog.rb

has_many :configuration_documents
has_many :documents, through: :configuration_documents

configuration_document.rb

belongs_to :document
belongs_to :document_catalog

This is my new method on documents_controller.rb:

  def new
    @document = Document.new
    @all_documents = DocumentCatalog.all
    @configuration_document = @document.configuration_documents.build
  end

This is my create method on documents_controller.rb version 1 (With this code, I can create the document).

   def create
    @document = Document.new(document_params)

    params[:document_catalogs][:id].each_line do |document|
      if !document.empty?
       @document.configuration_documents.build(:document_catalog_id => document)
      end
    end

    respond_to do |format|
      if @document.save
        format.html { redirect_to admin_document_path(@document), notice: 'Document was successfully created.' }
        format.json { render :show, status: :created, location: @document }
      else
        format.html { render :new }
        format.json { render json: @document.errors, status: :unprocessable_entity }
      end
    end
  end

Using the code above for create, I have this error when I try to Edit:

undefined method `model_name' for nil:NilClass on `<%= fields_for (@configuration_document) do |dc|%>`

This is my code for create action on documents_controller version 2:

    def create
    @document = Document.new(document_params)
    if params[:document_catalogs][:id]
      params[:document_catalogs][:id] = params[:document_catalogs][:id].reject(&:empty?).map(&:to_i)
      params[:document_catalogs][:id].each do |document|
        @miniature.configuration_documents.build(:document_catalogs_id => document)
      end
    end

    respond_to do |format|
      if @document.save
        format.html { redirect_to admin_document_path(@document), notice: 'Document was successfully created.' }
        format.json { render :show, status: :created, location: @document }
      else
        format.html { render :new }
        format.json { render json: @document.errors, status: :unprocessable_entity }
      end
    end
  end

Note: When I use the code above for the update, even the "new" doesn't work and I got this error on the create action:

NoMethodError - undefined method `reject' for "2":String:
params[:document_catalogs][:id] = params[:document_catalogs][:id].reject(&:empty?).map(&:to_i)

This is my update method on documents_controller.rb:

 def update
    @document = Document.find(params[:id])
    if params[:document_catalogs][:id]
      params[:document_catalogs][:id] = params[:document_catalogs][:id].reject(&:empty?).map(&:to_i)
      old_documents_catalogs = @document.configuration_documents.pluck(:document_catalog_id)
      new_dcos = params[:document_catalogs][:id] - old_documents_catalogs 
      old_documents_catalogs = old_documents_catalogs - params[:document_catalogs][:id] 
      new_dcos.each do |dc|
        @document.configuration_documents.build(:document_catalog_id => dc)
      end
      ConfigurationDocument.delete_all(:document_catalog_id => old_documents_catalogs)
    end
    if @document.update_attributes(document_params)
      flash[:success] = "document updated"
      redirect_to @document
    else
      render 'edit'
    end
 end

If I leave the update like the normal scaffold. I get the error:

undefined method `model_name' for nil:NilClass on `<%= fields_for (@configuration_document) do |dc|%>

The relevant part of the "documents form":

    <div class="form-group">
      <%= fields_for (@configuration_document) do |dc|%>
      <%= collection_select(:document_catalogs, :id, @all_documents, :id, :name, {}, class: 'form-control')%>
     <% end %>
   </div>

I really know that is a lot of things. But basically, If I use version one of "create", I can create but no edit/update

If I use version two of the create, I can't create, edit/update.

Regards.

Note that the behaviour of `update_attributes` has changed. What version of Rails are you using? How did you implement the `edit` action? Also, please edit your question to make it really clear what you are asking. Reduce to one version of code so we have a solid base for analysis. — Raffael, May 21 '16 at 00:22

Michael Gaskill · Answer 1 · 2016-05-21T02:57:03.913

Try this:

<%= fields_for :configuration_document, @configuration_document do |dc|%>

The field_for method takes 2 arguments, the model, and the model object. You were just missing the model.

In your first create method, you're using this:

params[:document_catalogs][:id].each_line do |document|

and I believe that what you really want is this:

params[:document_catalogs][:id].each do |document|

In the second create method, you're using this:

params[:document_catalogs][:id] = params[:document_catalogs][:id].reject(&:empty?).map(&:to_i)
params[:document_catalogs][:id].each do |document|

and I think that you really want to use this:

params[:document_catalogs].reject(&:empty?).map(&:to_i).each do |document|

Rails Edit/Update action not working with nested models (has_many :through)

1 Answers1