When I click submit on the form. The form doesn't load in the params the value that contains the checkbox. Matter of fact I got an error (Image shape can't be blank) due to the model

_form.html.erb

<%= form_for @image, html: { multipart: true } do |f| %>
  <% if @image.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@image.errors.count, "error") %> prohibited this image from being saved:</h2>

      <ul>
      <% @image.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :caption %><br>
    <%= f.text_field :caption %>
  </div>
  <div class="field">
    <%= f.label :image %><br>
    <%= f.file_field :image %>
  </div>
  <div class="field">
    <%= f.label :image_shape %><br>
    <%= select_tag(:image_shape, options_for_select([['landscape', 'landscape'], ['portrait', 'portrait']])) %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

image.rb

class Image < ActiveRecord::Base
 mount_uploader :image, ImageUploader
 #validation
 validates :image_shape , presence: true
end

images_controller.rb

class ImagesController < ApplicationController
  before_action :set_image, only: [:show, :edit, :update, :destroy]

  # GET /images
  # GET /images.json
  def index
    @images = Image.all
  end

  # GET /images/1
  # GET /images/1.json
  def show
  end

  # GET /images/new
  def new
    @image = Image.new
  end

  # GET /images/1/edit
  def edit
  end

  # POST /images
  # POST /images.json
  def create
    @image = Image.new(image_params)

    respond_to do |format|
      if @image.save
        format.html { redirect_to @image, notice: 'Image was successfully created.' }
        format.json { render action: 'show', status: :created, location: @image }
      else
        format.html { render action: 'new' }
        format.json { render json: @image.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /images/1
  # PATCH/PUT /images/1.json
  def update
    respond_to do |format|
      if @image.update(image_params)
        format.html { redirect_to @image, notice: 'Image was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: 'edit' }
        format.json { render json: @image.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /images/1
  # DELETE /images/1.json
  def destroy
    @image.destroy
    respond_to do |format|
      format.html { redirect_to images_url }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_image
      @image = Image.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def image_params
      params.require(:image).permit(:caption, :image, :image_shape)
    end
end

guinslym: I assume the html name.array is wrong,.. why don't you use f.select instead of select? this results in a different scope

pduersteler, : thks I see the difference in the name attr: now (image[image_shape]) compare toname="image_shape" for the select_tag

guinslym: yep, and as you are relying on mass assignment in your controller, it won't get picked up because it is outside of your "mass assignment scope", so to say