我正在创建一个收集项目信息的表单。型号，品牌，类别等。
我正在使用闭包树gem存储嵌套类别和jquery ajax来填充嵌套类别选项。
当我填写表格并提交时。然后我收到了错误。我无法弄清楚为什么我会收到这个错误。我觉得一切都好。
Started POST "/items" for 127.0.0.1 at 2016-02-04 23:32:43 +0200
Processing by ItemsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"TQoetryLPx2w7kIHki6mB4UDJFwjXm1nOvwPM120j2eP5wBiVVb22h1AjD487unP1MSZtnqddOe3xdTmjbBkwA==", "item"=>{"name"=>"name", "description"=>"desc", "brand"=>"brand", "model"=>"model", "quantity"=>"1", "unit_id"=>"2"}, "category"=>{"id1"=>"30", "id2"=>"31"}, "commit"=>"Create Item"}
User Load (0.1ms) SELECT `users`.* FROM `users` WHERE `users`.`id` = 1 ORDER BY `users`.`id` ASC LIMIT 1
asdas (0.1ms) BEGIN
(0.1ms) ROLLBACK
Rendered items/_form.html.erb (7.0ms)
Rendered items/new.html.erb within layouts/application (8.1ms)
Completed 500 Internal Server Error in 17ms (ActiveRecord: 0.3ms)
Rendered items/_form.html.erb (7.0ms)
Rendered items/new.html.erb within layouts/application (8.1ms)
Completed 500 Internal Server Error in 17ms (ActiveRecord: 0.3ms)
undefined method `map' for nil:NilClass
ActionView::Template::Error (undefined method `map' for nil:NilClass):
<div class="input-group">
<span class="input-group-addon">1</span>
-->> <%= f.collection_select(:category_id, @categories, :id, :name, {}, { :id => 'C1', name: 'category[id1]', class: 'form-control'}) %>
</div>
app/views/items/_form.html.erb:53:in `block in _app_views_items__form_html_erb__3272575439911272512_70018975348520'
app/views/items/_form.html.erb:1:in `_app_views_items__form_html_erb__3272575439911272512_70018975348520'
app/views/items/new.html.erb:5:in `_app_views_items_new_html_erb__1044924137833435696_47249300'
app/controllers/items_controller.rb:34:in `create'
_form.html.erb
<%= form_for @item, :html => { :class => "form-horizontal item" } do |f| %>
<% if @item.errors.any? %>
<div id="error_expl" class="panel panel-danger">
<div class="panel-heading">
<h3 class="panel-title"><%= pluralize(@item.errors.count, "error") %> prohibited this item from being saved:</h3>
</div>
<div class="panel-body">
<ul>
<% @item.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
</div>
<% end %>
<div class="form-group">
<%= f.label :name, :class => 'control-label col-lg-2' %>
<div class="col-lg-8">
<%= f.text_field :name, :class => 'form-control' %>
</div>
<%=f.error_span(:name) %>
</div>
<div class="form-group">
<%= f.label :description, :class => 'control-label col-lg-2' %>
<div class="col-lg-8">
<%= f.text_field :description, :class => 'form-control' %>
</div>
<%=f.error_span(:description) %>
</div>
<div class="form-group">
<%= f.label :category_id, :class => 'control-label col-lg-2' %>
<div class="col-lg-8">
<div class="input-group">
<span class="input-group-addon">1</span>
<%= f.collection_select(:category_id, @categories, :id, :name, {}, { :id => 'C1', name: 'category[id1]', class: 'form-control'}) %>
</div>
<div class="input-group">
<span class="input-group-addon">2</span>
<%= f.collection_select(:category_id, @categories, :id, :name, {}, { :id => 'C2', name: 'category[id2]', class: 'form-control'}) %>
</div>
<div class="input-group">
<span class="input-group-addon">3</span>
<%= f.collection_select(:category_id, @categories, :id, :name, {}, { :id => 'C3', name: 'category[id3]', class: 'form-control'}) %>
</div>
<div class="input-group">
<span class="input-group-addon">4</span>
<%= f.collection_select(:category_id, @categories, :id, :name, {}, { :id => 'C4', name: 'category[id4]', class: 'form-control'}) %>
</div>
<div class="input-group">
<span class="input-group-addon">5</span>
<%= f.collection_select(:category_id, @categories, :id, :name, {}, { :id => 'C5', name: 'category[id5]', class: 'form-control'}) %>
</div>
</div>
<%=f.error_span(:category_id) %>
</div>
<div class="form-group">
<%= f.label :brand, :class => 'control-label col-lg-2' %>
<div class="col-lg-8">
<%= f.text_field :brand, :class => 'form-control' %>
</div>
<%=f.error_span(:brand) %>
</div>
<div class="form-group">
<%= f.label :model, :class => 'control-label col-lg-2' %>
<div class="col-lg-8">
<%= f.text_field :model, :class => 'form-control' %>
</div>
<%=f.error_span(:model) %>
</div>
<div class="form-group">
<%= f.label :unit_id, :class => 'control-label col-lg-2' %>
<div class="col-lg-8">
<div class = "input-group">
<%= f.number_field :quantity, :class => 'form-control col-lg-2', :html => {'aria-label' => '...'} %>
<%= f.collection_select(:unit_id, @units, :id, :name, {}, { class: 'form-control col-lg-1'}) %>
</div>
</div>
<%=f.error_span(:unit) %>
</div>
<div class="form-group">
<div class="col-lg-offset-2 col-lg-8">
<%= f.submit nil, :class => 'btn btn-primary' %>
<%= link_to t('.cancel', :default => t("helpers.links.cancel")),
items_path, :class => 'btn btn-default' %>
</div>
</div>
<% end %>
<script>
$(document).ready( function() {
$('#C1').click(function() {
$.ajax({
url: "<%= children_category_path %>",
data: {
id : $('#C1 option:selected').val(),
which : "C1",
form : "item",
action: "<%= params[:action] %>"
},
dataType: "script"
});
});
$('#C2').click(function() {
$.ajax({
url: "<%= children_category_path %>",
data: {
id : $('#C2 option:selected').val(),
which : "C2",
form : "item",
action: "<%= params[:action] %>"
},
dataType: "script"
});
});
$('#C3').click(function() {
$.ajax({
url: "<%= children_category_path %>",
data: {
id : $('#C3 option:selected').val(),
which : "C3",
form : "item",
action: "<%= params[:action] %>"
},
dataType: "script"
});
});
$('#C4').click(function() {
$.ajax({
url: "<%= children_category_path %>",
data: {
id : $('#C4 option:selected').val(),
which : "C4",
form : "item",
action: "<%= params[:action] %>"
},
dataType: "script"
});
});
});
</script>
items_controller.rb
def new
@item = Item.new
@categories = Category.roots
@units = Unit.all
end
def create
@item = Item.new(create_params)
if @item.save
redirect_to @item
else
render 'new'
end
end
private
def create_params
data = params.require(:item).permit(:name, :description, :brand, :model, :quantity, :unit_id)
category_id = params.require(:category).permit(:id1,:id2,:id3, :id4, :id5).values.reject(&:empty?).compact.last
return data.merge(Hash["category_id" => category_id ])
end
类别根返回根类别，在此示例中，我有一个根类别。
Category.roots
<Category id: 30, name: "Category", parent_id: nil, sort_order: nil, created_at: "2016-02-04 20:43:57", updated_at: "2016-02-04 20:43:57", custom_fields: {}
答案 0 :(得分：0)
您需要添加@categories = Category.roots和@units = Unit.all
控制器中的create方法。