API Summary routes

In a previous blog post, I outlined my solution to summary routes, in short, every route in my API will have a matching summary route, the summary route is simply the route with a summary/ prefix.

If the GET endpoint of a route supports parameters the summary route should support the same parameters, in my experience, it will need additional parameters; as always, best shown with an example.

The summary route lives at summary/resource-types/[resource-type]/resources/[resource]/items, the GET endpoint has eight parameters, below I’ll show the expected output for each parameter.

In my API I have the following route /resource-types/[resource-type]/resources/[resource]/items. The GET endpoint returns a collection of the items assigned to the resource; it has four parameters for filtering, year, month, category and subcategory.

No parameters | Total sum of items
years | Summary for each year
year | Summary for the requested year
months | Summary for each month
month | Summary for the requested month
categories | Summary for each category
category | Summary for the requested category
subcategories | Summary for each subcategory
subcategory | Summary for the requested subcategory

So far I’ve not come across any negatives to this structure, yes, there are numerous parameters for the GET endpoint, I don’t consider that an issue, I’d rather have fewer routes than fewer GET parameters.

Dart Sass with Windows Linux Subsystem

Follow the steps below to setup sass, specifically dart-sass in the Windows Linux Subsystem.

  1. Download and extract the dart-sass release you are going to use, at the time of this post I opted for dart-sass-1.18.0-linux-x64.tar.gz
  2. Find your bash.rc, if you setup WLSS after the Fall Creators update it will be located at C:\Users\USERNAME\AppData\Local\Packages\{CanonicalGroupLimited.UbuntuonWindows_...}\LocalState\rootfs\home\LINUXUSER\ or similar.
  3. Add export PATH="/path/to/dart-sass:$PATH" to the end of the file, in my case export PATH="/mnt/c/Users/USERNAME/Documents/GitHub/dart-sass:$PATH"

Open bash, type sass --version to see if everything worked.

Where to put summary routes in your API?

I believe the response to the question is going to be different for every API, in my case I initially added them where I thought it made sense, at the level I thought I wanted to summarise.

To view the list of items assigned to a resource in the Costs to Expect API you browse as below;
/resource-type/[id]/resource/[id]/items.
To view the TCO (Total cost of ownership) for a resource, I added a summary route at /resource-type/[id]/resource/[id]/summary/tco.

This initially made sense, however, later, as I was adding year and month summaries my solution began to become unwieldy, longterm, I would end up with two mismatching trees, the main tree for the API and then another summary tree, secondly, using this structure, where would I put a summary for multiple resources?

I’ve come up with a solution that I think will solve my problems, there should be a summary route for every API endpoint, the summary routes are then merely the route prefixed with /summary.

In the case of the TCO for a resource, the summary route would be summary/resource-type/[id]/resource/[id]/items. No TCO in the URI, it is not necessary, you are summarising the items collection so you should expect a total.

My solution doesn’t fix all the issues, presently the annual summary for a resource lives at /resource-type/[id]/resource/[id]/summary/years. There is no matching endpoint for this summary route. The solution, GET parameters. The items collection has four filtering parameters, year, month, category and subcategory; the summary route should support the same parameters.

I’m confident that if I had spent a little more time researching I would have been able to find this solution in an article somewhere online, I didn’t and unfortunately, it took me a little while to realise. Hopefully, this blog post will help at least one other person.

Do not change URIs, oops

A core rule of the Internet, don’t change a URI. I’m going to change some, why, we all make mistakes.

I released the initial version of the Costs to Expect API during the summer of ’18. It turns out when you review your code/API after a short break you spot all the issues you were oblivious to during development.

Over the next 12 months, I’m going to extend the Costs to Expect API, an API that I intend on maintaining for a significant period; I need to record data for at least the next 13 years.

If there were one small issue with the URIs, I’d deal with it, change a couple of URIs and add redirects. There are numerous issues; I am not happy with the initial summary routes. I favour dashes in the URIs over underscores, some of the words are incorrect and other minor issues.

We haven’t pushed the service; it doesn’t exist. As far as I am aware I am the only consumer of the API. I believe it is OK to modify the URIs, as long as I do not modify them again they should remain the same for twenty times longer then they have existed.