New schema cheatsheet

This cheatsheet summarises the changes needed to update your database to use the new Keystone database schema, introduced in the Arcade release. For full instructions please consult the migration guide.

One-to-many (one-sided)

keystone.createList('User', { fields: { name: { type: Text } } });

keystone.createList('Post', {
  fields: {
    title: { type: Text },
    content: { type: Text },
    author: { type: Relationship, ref: 'User', many: false },
  },
});

Migration strategy

• No changes are required for these relationships.

Many-to-many (one-sided)

keystone.createList('User', { fields: { name: { type: Text } } });

keystone.createList('Post', {
  fields: {
    title: { type: Text },
    content: { type: Text },
    authors: { type: Relationship, ref: 'User', many: true },
  },
});

Migration Strategy

PostgreSQL

• Rename Post_authors to Post_authors_many.
• Rename Post_id to Post_left_id and User_id to User_right_id.

MongoDB

• Create a collection post_authors_manies with fields Post_left_id and User_right_id.
• Move the data from posts.authors into post_authors_manies.
• Delete posts.authors.

One-to-many (two-sided)

keystone.createList('User', {
  fields: {
    name: { type: Text },
    posts: { type: Relationship, ref: 'Post.author', many: true },
  },
});

keystone.createList('Post', {
  fields: {
    title: { type: Text },
    content: { type: Text },
    author: { type: Relationship, ref: 'User.posts', many: false },
  },
});

Migration strategy

PostgreSQL

• Drop the User_posts table.

MongoDB

• Remove users.posts.

Many-to-many (two-sided)

keystone.createList('User', {
  fields: {
    name: { type: Text },
    posts: { type: Relationship, ref: 'Post.authors', many: true },
  },
});

keystone.createList('Post', {
  fields: {
    title: { type: Text },
    content: { type: Text },
    authors: { type: Relationship, ref: 'User.posts', many: true },
  },
});

Migration strategy

PostgreSQL

• Drop the Post_authors table.
• Rename User_posts to User_posts_Post_authors.
• Rename User_id to User_left_id and Post_id to Post_right_id.

MongoDB

• Create a collection user_posts_post_authors with fields User_left_id and Post_right_id.
• Move the data from users.posts into user_posts_post_authors.
• Delete users.posts.
• Delete posts.authors.

One-to-one (two-sided)

keystone.createList('User', {
  fields: {
    name: { type: Text },
    post: { type: Relationship, ref: 'Post.author', many: false },
  },
});

keystone.createList('Post', {
  fields: {
    title: { type: Text },
    content: { type: Text },
    author: { type: Relationship, ref: 'User.post', many: false },
  },
});

Migration strategy

PostgreSQL

One to one relationships in the before state had a foreign key column on each table. In the after state, only one of these is stored. Because of the symmetry of the one-to-one relationship, Keystone makes an arbitrary decision about which column to use.

• Identify the foreign key column which is no longer required, and delete it.
• In our example above we would delete the Post.author column.

MongoDB

One to one relationships in the before state had a field in each collection. In the after state, only one of these is stored. Because of the symmetry of the one-to-one relationship, Keystone makes an arbitrary decision about which field to use.

• Identify the field which is no longer required, and delete it.
• In our example above we would delete the post.author field.