Relations

Every foreign key gives a field on both sides. With blog_posts.author_id referencing authors.id:

type BlogPost {
  author: Author                    # the row the key points at
}

type Author {
  blogPosts(where: BlogPostWhere, orderBy: [BlogPostOrderBy!], limit: Int, offset: Int): [BlogPost!]!
}

{
  authors {
    fullName
    blogPosts { title author { email } }
  }
}

Names

• The field on the side holding the key is named after the key without its id suffix: author_id gives author. A composite key, or one without that suffix, is named after the type it points at (user).
• The field on the other side is the plural of the type holding the key: blogPosts.
• Two keys from one table to the same table are told apart by the key: messagesBySenderId and messagesByRecipientId.
• A name already taken by a column or another relation gets a number: user2.

The naming and rename options change them.

Batching

Relations are resolved with DataLoader, one loader per request. Loading 100 posts with their authors takes two queries, one for the posts and one for all their authors, instead of 101. Loaders never share data between requests.

Composite keys

Foreign keys over several columns work the same way: the relation matches on all the columns.

Views

SQL views are exposed read-only: they can be listed, counted, filtered and followed, but never written. A view has no keys of its own, so declare them with the views option to give it a by-key query, a connection and relations:

InverseModelModule.forRoot({
  url: process.env.DATABASE_URL!,
  views: {
    published_posts: {
      primaryKey: ['id'],
      foreignKeys: [{ columns: ['author_id'], table: 'authors', references: ['id'] }],
    },
  },
});

MongoDB references

MongoDB has no foreign keys, so references are inferred:

• An id field named author_id or authorId points at the author or authors collection, and category_id at categories.
• A DBRef points at the collection it names.
• An array of ids named tag_ids or tagIds is a list of tags.

See MongoDB.