When creating objects, created_at stores microsecond precision that json can't match

Question

I just noticed something which is causing me a tad bit of trouble.

I am creating an object. This object goes into the database with this:

created_at: "2015-11-12 08:37:35.413663"

I didn't realize it stores beyond .413

You can confirm this is saved and not simply for our viewing pleasure by doing the following: object.created_at.nsec #=> 413663000

When my front-end receives my JSON, the created_ at attribute becomes: "2015-11-12T08:37:35.413Z", which I would expect. The problem here is that we lose valuable information because now we don't have the 633 microseconds.

Indeed, if you do "2015-11-12T08:37:35.413Z".to_time.nsec #=> 413000000.

What this means is when you do the following, you're going to get no item:

Object.where(created_at: object.created_at.as_json).first #=> nil

How does one mitigate this? How does one account for the microseconds, or rather, query for created_at, with only millisecond precision hope.

Answer 1

Ultimately, I decided on changing the datetime columns in my DB.

I basically applied the following wherever relevant in a migration:

change_column table, column, :datetime, limit: 3

That successfully makes sure that my :datetime columns all only go to the milliseconds.

I think it is a good change because when the sole purpose of my back-end is to render a JSON API, then I think through and through it should be cohesive. JSON API standards are ISO 8601. As such, I'd like my DB to adhere to that.