title: param is missing or the value is empty: user
body: <p>I'm using <a href="http://www.getpostman.com/" rel="nofollow noreferrer">Postman</a> to test my API and I'm getting the error <code>param is missing or the value is empty: user</code> when making a call to <code>http://localhost:3000/users.json</code> to create a new user. All the parameters seem to be ok. </p>
  
  <p>I set this in my application controller:</p>
  
  <pre><code>protect_from_forgery with: :null_session 
  </code></pre>
  
  <p>My controller method is the basic scaffold generated method:</p>
  
  <pre><code>def create
    @user = User.new(user_params)
  
    respond_to do |format|
      if @user.save
        format.html { redirect_to @user, notice: 'User was successfully created.' }
        format.json { render :show, status: :created, location: @user }
      else
        format.html { render :new }
        format.json { render json: @user.errors, status: :unprocessable_entity }
      end
    end
  end
  </code></pre>
  
  <p>What am I doing wrong?</p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>Here's a screenshot of what I'm doing in Postman.</p>
  
  <p><img src="https://i.stack.imgur.com/64ioK.png" alt="enter image description here"></p>