试图在Ruby on Rails中使用表单提交创建模型对象

Question

First time with ROR and I'm trying to create a new model object from the index view on form submission. I think I got it figured out, but I'm getting:

uninitialized constant UsersController

In my view I have:

=form_for :user, :url => { :action => "new", :controller => "user" } do |f|
    = f.text_field :username, :placeholder => 'Username', :size => 30
    %br
    = f.text_field :email, :placeholder => 'E-mail', :size => 30
    %br
    = f.password_field :password, :placeholder => 'Password', :size => 30
    %br
    %br
    = f.submit_tag 'Sign Up'

In my controller I have:

def new
user_info = :params[:user]
    @user = User.create!(user_info)
    flash[:notice] = "#{@user.username} has been added!  Please fill out your profile page."
    redirect_to user_path
end

Can anyone see why I'm getting this?

Answer 1

First issue was just using f.submit_tag with a form_for helper. Other comments..

When doing forms like this in Rails you should use the new action to setup an empty model for the form to work on

def new
  @user = User.new

  respond_to do |format|
    format.html  # new.html.erb
    format.json  { render :json => @user }
  end
end

The form will then submit to the create action, where you read the params and use those to create a User object that you'll save

def create
  @user = User.new(params[:post])

  respond_to do |format|
    if @user.save
      format.html  { redirect_to(@user, :notice => 'User was successfully created.') }
      format.json  { render :json => @user, :status => :created, :location => @user }
    else
      format.html  { render :action => "new" }
      format.json  { render :json => @post.errors, :status => :unprocessable_entity }
    end
  end
end

The respond_to blocks here let you check for additional file extensions, usually .json or .xml, and give you a way to format your output for each of those extensions.

For the show action you could have the following:

def show
  @user = User.find(params[:id])

  respond_to do |format|
    format.html  # show.html.erb
    format.json  { render :json => @user }
  end
end

and go to /users/1 you would see the your view rendered (this is the default thus the empty line there with the comment #show.html.erb you don't have to do anything assuming you have a view)

and if you go to /users/1.json you'll get just the result of @user.to_json which is useful for talking to Rails from your Javascript

And regarding the undefined constant issue:

1. Check that your UsersController isn't missing any end lines

2. Check that the relevant User model and UsersController have all the correct naming conventions so as not to confuse Rails

users_controller.rb:

class UsersController < ApplicationController
...
end

user.rb:

class User < ActiveRecord::Base
...
end