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POcan't use @user in form_for in rails 4 getting a nil error
 

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  1. POcan't use @user in form_for in rails 4 getting a nil error
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    <p>I know that there are many questions a but every solution that i've tried did not work. I am trying to create a sign in form, but I am getting the following error First argument in form cannot contain nil or be empty</p> <p>replacing <code>@user</code> with <code>User.new</code> will solve the error , but than I can't check for <code>@user.errors.any</code>..</p> <p>any suggestions?</p> <pre><code>&lt;h1&gt;Sign up&lt;/h1&gt; &lt;div class="row"&gt; &lt;div class="span6 offset7"&gt; &lt;%= form_for @user do |f| %&gt; &lt;% if @user.errors.any? %&gt; &lt;div id="error_explanation"&gt; &lt;h2&gt;&lt;%= pluralize(@user.errors.count, "error") %&gt; prohibited this user from being saved:&lt;/h2&gt; &lt;ul&gt; &lt;% @user.errors.full_messages.each do |msg| %&gt; &lt;li&gt;&lt;%= msg %&gt;&lt;/li&gt; &lt;% end %&gt; &lt;/ul&gt; &lt;/div&gt; &lt;% end %&gt; &lt;%= f.label :name %&gt; &lt;%= f.text_field :name %&gt; &lt;%= f.label :email %&gt; &lt;%= f.text_field :email %&gt; &lt;%= f.label :password %&gt; &lt;%= f.password_field :password %&gt; &lt;%= f.label :password_confirmation, "Confirmation" %&gt; &lt;%= f.password_field :password_confirmation %&gt; &lt;br&gt; &lt;%= f.submit "Create my account", class: "btn btn-large btn-primary" %&gt; &lt;% end %&gt; &lt;/div&gt; &lt;/div&gt; </code></pre> <p>and my controller code is</p> <pre><code>class UsersController &lt; ApplicationController before_action :set_user, only: [:show] def new @user = User.new end # POST /user # POST /user.json 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 action: 'show', status: :created, location: @user } else format.html { render action: 'new' } format.json { render json: @user.errors, status: :unprocessable_entity } end end end # PATCH/PUT /user/1 # PATCH/PUT /user/1.json def update respond_to do |format| if @user.update(user_params) format.html { redirect_to @user, notice: 'User was successfully updated.' } format.json { head :no_content } else format.html { render action: 'edit' } format.json { render json: @user.errors, status: :unprocessable_entity } end end end def edit end # DELETE /user/1 # DELETE /user/1.json def destroy @user.destroy respond_to do |format| format.html { redirect_to users_url } format.json { head :no_content } end end private # Use callbacks to share common setup or constraints between actions. def set_user @user = User.find(params[:id]) end # Never trust parameters from the scary internet, only allow the white list through. def user_params params.require(:user).permit(:name, :email, :password) end end </code></pre>
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