Rails: How do I print the request parameters?

I have a Rails 3 application and I want to print in the view the request parameters. How do I do it?

Edit:

The purpose is to see what is being sent in a Form.

If you wanted to print all of the parameters, the easiest way would be to use the inspect

puts params.inspect

or better, use the Rails logger

Rails.logger.debug params.inspect

In your html/ERB, you can use

<%= params.inspect %>

I would use debug(params). That will give you a nicely formatted view of them.

Learnt this from the Ruby Hero James Edward Gray II on this episode of Ruby Rogues podcast which I highly recommend. raise is a swiss army knife for inspecting anything in your Rails code which prints it nicely on your browser.

> raise params.inspect

Parameters are stored in the params hash. For example, if there was a title parameter, you could display it in your view using <%= params[:title] %>.

pretty_print also can be useful, in ruby and rails apps both

pp params

pretty_print doc: http://ruby-doc.org/stdlib-2.1.0/libdoc/pp/rdoc/PP.html

Something like

<%= params.inspect %>

works, but what I would like to add is the following gem and Chrome plugin which was literally an eye-opener.

I am putting it here because I think it will help people check out params hashes, see SQL queries or view Errors.

You can use for models, controllers, etc.

puts YAML::dump(params)

Source: Ruby / Rails alternative to PHP print_r() and var_dump()

For views:

DebugHelper’s debug(object)

In your case:

DebugHelper’s debug(params)

Source: http://guides.rubyonrails.org/getting_started.html#creating-articles > When a form is submitted, the fields of the form are sent to Rails as parameters. These parameters can then be referenced inside the controller actions, typically to perform a particular task. To see what these parameters look like, change the create action to this:

def create
  render plain: params[:article].inspect
end

---

The response when POST'ing a form to the targeted #create route would be a plain-text hash output of params[:article]

ap params.to_unsafe_h

Example output:

[19] pry(#<AssessmentsController>)> ap params.to_unsafe_h
{
                  "utf8" => "✓",
    "authenticity_token" => "",
            "assessment" => {
        "form_field_10" => "0",
        "form_field_12" => "1"
    },
                "commit" => "Create Assessment",
            "controller" => "assessments",
                "action" => "create"
}
=> nil

Uses https://github.com/awesome-print/awesome_print

Based on https://stackoverflow.com/a/49342607