Rails表单未从另一个控制器呈现

Question

I am making a simple todo list application where I have this below code in my todos/new template

todos/new.html.erb

<div class="new-task">
    <%= form_tag {controller: "todos", action: "new"} , method: "post", class: "form-group" do %>
        <div class="row">
            <div class="col-md-8 col-sm-8">
                <%= text_field_tag "todos[task]", "", class: "form-control" %>
            </div>
            <div class="col-md-4 col-sm-4">
                <%= submit_tag "Add", class: "btn btn-primary" %>
            </div>
        </div>
    <% end %>
</div>

When I am trying to render this view from another controller's view using

<%= render template: 'todos/new' %>

I am getting a nasty error with below stack trace.

SyntaxError in ToolsController#index

app/views/todos/new.html.erb:2: syntax error, unexpected ':', expecting '}'
app/views/todos/new.html.erb:2: syntax error, unexpected ',', expecting '}'
app/views/todos/new.html.erb:2: syntax error, unexpected tLABEL
app/views/todos/new.html.erb:2: syntax error, unexpected ',', expecting keyword_end
app/views/todos/new.html.erb:2: syntax error, unexpected keyword_do, expecting keyword_end
app/views/todos/new.html.erb:19: syntax error, unexpected keyword_ensure, expecting end-of-input
app/views/tools/index.html.erb:18:in `_app_views_tools_index_html_erb__1039417368_95034624'

Please help in resolving this. Thanks in advance!

Answer 1

form_tag(url_for_options = {}, options = {}, &block)

The form_tag helper accepts 2 arguments: the path for the action and an options hash. This hash specifies the method of form submission and HTML options such as the form element's class

In your case you need to wrap the controller and action between curly braces, and the rest of options within parenthesis, like:

<%= form_tag({controller: 'todos', action: 'new'}, class: 'form-group') do |form| %>
  ...

This way Rails will turn the hash into a valid URL.

Same could be achieved by passing the URI corresponding to both, controller and action, like:

<%= form_tag('/todos', class: 'form-group') do |form| %>
  ...

Note if you leave a white space between the form_tag and the parenthesis you will have a syntax error, unexpected tLABEL append= form_tag error and the default method for the form_tag helper is POST, so you don't need to specify it in this case.