Undefined method `stringify_keys' in Messages

问题:

I am getting the following error when I try to submit a form (the form shows up when 1 user wants to message another user)

NoMethodError in MessagesController#create

undefined method `stringify_keys' for "":String
Rails.root: /Users/fkhalid2008/loand

Application Trace | Framework Trace | Full Trace
app/controllers/messages_controller.rb:31:in `new'
app/controllers/messages_controller.rb:31:in `create'

Here is the relevant code from Messages Controller:

def new
  @message = Message.new

  if params[:reply_to]
    @reply_to = @user.received_messages.find(params[:reply_to])
    unless @reply_to.nil?
      @message.to = @reply_to.sender.login
      @message.subject = "Re: #{@reply_to.subject}"
      @message.body = "\n\n*Original message*\n\n #{@reply_to.body}"
    end
  end
end

def create
  @message = Message.new(params[:message])
  @message.sender = @user
  @message.recipient = User.find_by_login(params[:message][:to])

  if @message.save
    flash[:notice] = "Message sent"
    redirect_to user_messages_path(@user)
  else
    render :action => :new
  end
end

How do I fix this?

More supporting code is below:

MESSAGES>NEW VIEW (This is where Form is being created)

<%= form_for @message, :url => messages_path(:user_id => @user) do |f| %>
<br>
<br />
<br />
<div class="field">
<label>Name</label>
<input type="text" name="name" id="contact_name" class="required" />
</div>

<div class="field">
<label>Email</label>
<input type="text" name="email" id="contact_email" class="required" />
</div>

<div class="field">
<label>Subject</label>
<input type="text" name="subject" id="contact_subject" class="required" />
</div>

<div class="field">
<label>Message</label>
<textarea name="message" rows="8" cols="25" id="contact_message" class="required max_len", max_length=1000 /></textarea>
</div>
<div class="btn">
<%= submit_tag 'Send Message' %>
</div>

<% end %>

MESSAGE MODEL

class Message < ActiveRecord::Base

is_private_message

attr_accessor :to

end

USER MODEL

class User < ActiveRecord::Base

has_many :posts  
has_one :profile
has_private_messages

attr_accessible :email

validates_presence_of :email
validates_uniqueness_of :email, :message =>"Hmm, that email's already taken"
validates_format_of :email, :with => /^([^\s]+)((?:[-a-z0-9]\.)[a-z]{2,})$/i, :message => "Hi! Please use a valid email"

end

POSTS>INDEX VIEW (This is where Form is being linked to)

<table class="table table-striped">
<tbody>
<% @posts.each do |post| %>
<tr>
<td>I am a <%= post.title %> getting married in <%= post.job %> in <%= post.location %>, and looking for a <%= post.salary %>. My budget is <%= post.salary %>.</td>
<td> <button class="btn" data-toggle="button" onClick="javascript:location.href = '/messages/new';" />Contact</button></td>
<td><%= time_ago_in_words(post.created_at) %> ago.</td>
<!--/. 
<td><%= link_to 'Show', post %></td>
<td><%= link_to 'Edit', edit_post_path(post) %></td>
<td><%= link_to 'Destroy', post, :confirm => 'Are you sure?', :method => :delete %></td>
-->
</tr>
<% end %>
</tbody>
</table>

DEVELOPMENT LOG

Started POST "/messages" for 127.0.0.1 at Sun Apr 22 01:54:57 +0500 2012
Processing by MessagesController#create as HTML
Parameters: {"name"=>"faisal", "commit"=>"Send Message", "authenticity_token"=>"Qyww9hP6jLmqpQ+ua21FAk9vePju8Gpq39Gpaflf3wE=", "utf8"=>"\342\234\223", "subject"=>"testing", "message"=>"hello", "email"=>"[e-mail]"}
User Load (0.1ms)  SELECT "users".* FROM "users" LIMIT 1

Completed 500 Internal Server Error in 17ms

NoMethodError (undefined method `stringify_keys' for "hello":String):
app/controllers/messages_controller.rb:31:in `new'
app/controllers/messages_controller.rb:31:in `create'

回答1:

Now I see. You've built you form in a completely inconsistent way:

<%= form_for @message, :url => messages_path(:user_id => @user) do |f| %>

and then:

<input type="text" name="name" id="contact_name" class="required" />

what leads you to the situation where this text field has nothing to do with the message. Do you see any mention of message within the last tag?

Solution is simple: use helpers.

Instead of your markup:

<label>Name</label>
<input type="text" name="name" id="contact_name" class="required" />

use helpers:

<%= f.label :name %>
<%= f.text_field :name %>

And your fields will become properly named (like message[name]) and you'll get in your controller proper params[:message]. Of course, you can make it manually but practice shows that it isn't the best decision.

Repeat this step for every of your other fields.

回答2:

What I would guess is happening is params[:message] isn't a hash as Rails expects it to be. You should definitely follow jdoe's advice and post your form code b/c I would suspect that it's not right.

Additionally, you can see what data you're posting to your app in the development log. Post that as well. It'll look something like:

Started POST "/message" for 127.0.0.1 at 2012-04-19 16:49:22 -0400
  Processing by MessagesController#create as HTML
  Parameters: {"key"=>"value"}

The "Parameters" is what you want to be looking at.

回答3:

When you call Message.new(params[:message]), params[:message] needs to be a hash with the message attributes. In your form, and consequently in your post as shown by the logfile, params[:message] is a string.

Change

<textarea name="message" rows="8" cols="25" id="contact_message" class="required max_len", max_length=1000 /></textarea>

to

<textarea name="message[message]" rows="8" cols="25" id="contact_message" class="required max_len", max_length=1000 /></textarea>

or better

<%= f.text_area :message, :rows => 9, :cols => 25, :class => "required max_len", :max_length => 1000 %>

But - there are a ton of other errors in your form that you will encounter soon - for example, there's no message[to] parameter, yet you're expecting one in your controller. I suggest reading up on a few Rails tutorials such as this one.