Batch loading

Background

Many components on the page might require access to the same entity. This cannot cause multiple fetches, as it’s a waste of bandwidth and time.

Same goes for a lot of individual objects - if we’re showing 50 entities in a grid - they must be fetched in bulk, not doing 50 separate requests.

Rules

• Batch loading of the same entity

• Batch loading of multiple entities at the same time whenever possible.

  • Always question loading objects one by one if showing more than one at a time.

How to test this behavior

Always test your component and application behavior by checking out ‘networking’ tab of your Dev Tools.

Be able to explain each and every request made by your application - and make them a decision, not an accident.

Make it a job of your persistence layer to coordinate loading.

Implementation hints

Batch requests for the same entity

Cache promises in the persistence layer. Return the same promise if available. Decide if refetch necessary there.

Batch requests for multiple entities

Always check if the API allows for batching GETs - it usually does. Demand it from your Backend team if needed.

In the persistence layer - gather IDs to be fetched for a single ‘tick’. Then gather them up into a single request, and resolve all of the promises after fetching.