有人可以帮我解决这个错误吗？
帖子中的 NoMethodError#create
显示 C:/Users/User/Documents/website/app/views/posts/_form.html.erb 其中第 24 行提出：
nil:NilClass 的未定义方法“收集”
提取的源代码（第 24 行附近）：
23: <%= f.label :categoria %>
24: <%= f.select :categoria_id, @categoria.collect { |c| [ c.name, c.id ] } %>模板包含的痕迹：app/views/posts/new.html.erb
我的 _form.html.erb
<%= form_for(@post, :html => { :multipart => true }) do |f| %>
<% if @post.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(@post.errors.count, "error") %> prohibited this post from being saved:</h2>
<ul>
<% @post.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :titulo %><br />
<%= f.text_field :titulo %>
</div>
<div class="field">
<%= f.label :conteudo %><br />
<%= f.text_area :conteudo %>
</div>
<div class="field">
<%= f.label :categoria %><br />
<%= f.select :categoria_id, @categoria.collect { |c| [ c.name, c.id ] } %>
</div>
<br />
<div class="field">
<%= f.file_field :avatar %>
</div>
<br />
<div class="actions">
<%= f.submit %>
</div>
<br />
<% end %>
我的控制器：
class PostsController < ApplicationController
# GET /posts
# GET /posts.json
def index
@posts = Post.all
respond_to do |format|
format.html # index.html.erb
format.json { render json: @posts }
end
end
# GET /posts/1
# GET /posts/1.json
def show
@post = Post.find(params[:id])
respond_to do |format|
format.html # show.html.erb
format.json { render json: @post }
end
end
# GET /posts/new
# GET /posts/new.json
def new
@post = Post.new
@categoria = Categorium.all
respond_to do |format|
format.html # new.html.erb
format.json { render json: @post }
end
end
# GET /posts/1/edit
def edit
@post = Post.find(params[:id])
@categoria = Categorium.all
end
# POST /posts
# POST /posts.json
def create
@post = Post.new(params[:post])
respond_to do |format|
if @post.save
format.html { redirect_to @post, notice: 'Post was successfully created.' }
format.json { render json: @post, status: :created, location: @post }
else
format.html { render action: "new" }
format.json { render json: @post.errors, status: :unprocessable_entity }
end
end
end
# PUT /posts/1
# PUT /posts/1.json
def update
@post = Post.find(params[:id])
respond_to do |format|
if @post.update_attributes(params[:post])
format.html { redirect_to @post, notice: 'Post was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: "edit" }
format.json { render json: @post.errors, status: :unprocessable_entity }
end
end
end
# DELETE /posts/1
# DELETE /posts/1.json
def destroy
@post = Post.find(params[:id])
@post.destroy
respond_to do |format|
format.html { redirect_to posts_url }
format.json { head :no_content }
end
end
end