Trashinator - Pre-plan

Taking inspiration from Katie Patrick, I'm building an app to help people make less trash.

It's tempting to dive in and code, especially when you're planning a relatively small application. The catch is, that's how you end up with unfixable design flaws and spaghetti code. I went ahead with some standard planning tools.

User stories

Planning the first draft, I produced these user stories. Not set in stone, just something to work with.

As a responsible person, I want to:

As a data curator, I want to:

Conceptual object model

Based on the user stories, I put together a conceptual object model.

Trashinator conceptual object

Planning probably paid off. My first instinct was that the User Profile would reference a single Household, which in turn keeps track of the number of people and general location notes. The Trash records would just link back to the User Profile.

But - what happens to all the stats if the user updates the Household? A Trash record that originally came from a house of 4 people could retroactively end up claiming it only served 2, and there would be no way to catch it. Can't have that.

You could make every Trash record store all the Household details, but that makes for a lot of data duplication. I've settled on making the Households effectively immutable behind the scenes; if the user decides to change details, they'll actually get a new Household that will be assigned to future Trash records.

You might notice I chucked out some ideas from the original user stories. Not accidental. Some things (teams) might come back, but would have been overkill for a first iteration. Others (household income) I decided against. Wealth shouldn't entitle you to pollute more.


Here's a pass at what the main tracking page will look like.

Web interface with fields to enter gallons of trash taken

That's plenty to work with. Next up ... write some code.