Accessing URL Parameters in the Params Hash
The params hash contains all the url and post parameters that are passed to your application. We can hit it in out controller, and in our view to get values from the URL.
Say we hit a url like this:
we would be able to call
params[:catname] to get the catname
We can also create a route to match params. In our routes file, we might put something like:
get 'cats/:id' => 'cats#show'
We can then hit a URL like this:
In the params hash, we now have an id. We can do
params[:id] to get the value from the url.
Exercise - Make a calculator
We are going to make a simple calculator, you will be able to give it two numbers, and have it give you the sum.
First create a controller and route. The routes should have space for two numbers. It should be possible to hit a URL like this:
Retrieve the values and store in instance variables
Now in your controller, retrieve these from the params hash and store them in instance variables, @number_1 and @number_2
Sum them in the view
Finally create a view. In the view, sum together the two numbers, giving a nice output.
Try and think of a way you can make this work using a form. You will need to change the route to accomplish this.