`Field::BelongsTo`

The BelongsTo association field wraps a belongs_to association on your model. By default it shows a link to the associated record on display pages and on edit and new pages it renders a searchable dropdown field.

BelongsTo field for a Person association filtered by "be" input

How to add a BelongsTo field

To add the basic BelongsTo field to a repository, return it as part of the #fields method:

def fields
  [
    Field::BelongsTo.new(:person)
  ]
end

BelongsTo fields use the same searchable options as the associated repository. This also means that if the repository has no searchable fields, the filter input doesn’t work.

Search

Not searchable by default. The field isn’t backed by a real column, so enabling it needs a searchable lambda - see Search for columns in an associated table.

`#collection_query`

The chainable #collection_query method lets you control what records are included in the dropdown. It accepts a proc, which is called when the user opens the dropdown or changes the filter input. The proc receives an ActiveRecord::Relation with all records matching the filter query.

Field::BelongsTo.new(:person)
  .collection_query(-> (query:) {
    query.some_scope
  })

The proc can accept the following keyword arguments:

context: The Uchi::Context we’re currently processing.
query: The ActiveRecord::Relation described above.

How to limit what records are returned

You can use #collection_query to limit what records are returned. The currently logged-in user is available as context.user, see Current user.

For example, if your User model has an authorized_people method that returns the people records the current user is allowed to access, you could do something like:

Field::BelongsTo.new(:person)
  .collection_query(-> (context:, query:) {
    query.where(id: context.user.authorized_people)
  })

How to control the order of records in dropdowns

When opening the record selector of a BelongsTo field the records are returned in the default order defined by the repository. To do something else, pass a proc to the #collection_query method:

Field::BelongsTo.new(:person)
  .collection_query(-> (query:) {
    query.reorder(:first_name, :last_names)
  })

The proc receives an ActiveRecord::Relation with all records returned from the repository. Note that you might have to use #reorder, not just #order, since the relation may already have an order defined.

The dropdown displays the title of the record. For example, a Person repository may use the name attribute as its title. To customize the title for a record, implement Repository#title, see repositories documentation for details.

BelongsTo field for polymorphic associations

Out of the box, Field::BelongsTo works for regular belongs_to associations as well as polymorphic ones. However, for polymorphic associations the field is not shown in forms (ie edit or new pages) since Uchi cannot guess what models to show in the associated record dropdown. Uchi removes edit and new from the field’s views automatically.

To edit the association, add explicit fields for the polymorphic attributes, ie:

def fields
  [
    Field::BelongsTo.new(:owner),
    Field::String.new(:owner_type).on(:edit, :new),
    Field::Number.new(:owner_id).on(:edit, :new),
  ]
end

or create a custom field that provides a user interface to select whatever models you want to choose between.

Field::BelongsTo