Michael Harper

Rails makes it easy to find the first row of a query:

Order.find(:first)

But what if you want the last one? It’d be great to be able to go:

Order.find(:last)

… especially if you could pass in conditions, etc.

Well, this isn’t general purpose, but it tends to get you the last one that was created. Can be useful in testing circumstances:

last_order = Order.find(:first, :conditions => 'id = (select max(id) from orders)')

I’ve been working on some code that gets a list of “old” orders based on the created_at value for an order. Of course, I wrote a test using a fixture that gets the list of old orders and makes assertions about it. I was not as rigorous as I should have been and simply checked to make sure the correct count of orders was returned and went along my merry way.

Today the test broke when I made some other changes. During my investigation, I printed out the contents of the orders and discovered the created_at and updated_at values were being set to all zeros. OK, that would explain why they’re considered “old” if they’re from “the beginning of time.” But I still wanted to be able to put values in for created_at that would cause an order to be too new to be included in the query. So, I figured I’d do something like this:

created_at: <%= Time.now %>

No workie; still zeros. Well, thanks to this blog entry, I was able to get it right:

created_at: <%= Time.now.to_s(:db) %>

One of the things that has been bugging me about my REST interfaces is that, although they are thoroughly tested in functional tests with all the GETs and POSTs and PUTs (and occasionally DELETEs), it just isn’t quite the same as literally POSTing the XML.

So, this morning I took the time to figure out a way to do this. It turns out that with an integration test, it’s quite easy. It’s also probably the Right Place™ to do this.

Witness:

class RestXmlTest < ActionController::IntegrationTest
  fixtures :model_fixture

  # Test creating a new resource by actually POSTing the XML.
  def test_create_resource
    post "/path_to_resource.xml",
      "<resource><attribute_1>attribute value</attribute_1>...</resource>",
      {:content_type => "application/xml"}

    assert_response 201
  end
end