Writing Specifications

Specifications are used to retrieve information. They begin with a model. The model describes the types of facts, and how they are related to each other.

const model = buildModel(b => b
  .type(Site)
  .type(Post, m => m
    .predecessor("site", Site)
  )
);

The model is used to create a specification. Given a starting point, the specification finds related facts. Usually, you want to find successors.

const postsInSite = model.given(Site).match(site =>
  site.successors(Post, post => post.site)
);

This specification finds all successors of type Post related to the predecessor Site.

Call the j.query method to retrieve the facts.

const posts = await j.query(postsInSite, site);