Field Discovery

Typically you declare each field explicitly in your resource. Field discovery is the alternative: discover_columns and discover_associations inspect your model's database columns and associations and configure the fields for you.

# app/avo/resources/user.rb
class Avo::Resources::User < Avo::BaseResource
  def fields
    discover_columns
    discover_associations
  end
end

Called with no arguments, discovery maps every column and association using Avo's default mappings — string columns become text fields, belongs_to associations become belongs_to fields, and so on. Rails enums are detected automatically and rendered as select fields, and sensitive columns like encrypted_password or password_digest are never discovered.

Scope which fields are discovered

If you only want a few fields discovered, pass only. To discover everything except a few, pass except.

# app/avo/resources/post.rb
class Avo::Resources::Post < Avo::BaseResource
  # ...

  def fields
    discover_columns only: [:title, :body, :published_at]
    discover_associations except: [:audit_logs]
  end
end

INFO

Rich text bodies and tags are discovered by discover_columns, while attachments and regular associations are discovered by discover_associations. Scope them from the matching method — discover_associations only: [:tags] has no effect.

Pass options to every discovered field

Any other keyword argument is forwarded to every discovered field. This is useful when you'd otherwise repeat the same option across many fields.

# app/avo/resources/post.rb
class Avo::Resources::Post < Avo::BaseResource
  # ...

  def fields
    discover_columns help: "Automatically discovered fields"
    discover_associations searchable: false
  end
end

Combine manual and discovered fields

Discovery plays nicely with explicit declarations — fields render in the order they're defined. Use except to avoid declaring a field twice.

# app/avo/resources/project.rb
class Avo::Resources::Project < Avo::BaseResource
  # ...

  def fields
    field :custom_field, as: :text

    discover_columns except: [:custom_field]
    discover_associations

    field :another_custom_field, as: :boolean
  end
end

Override how columns map to fields

Avo decides each column's field type by checking, in order: the model's Rails enums, the column's name, then the column's database type. You can override the last two globally from the initializer.

If a column name should always get a specific field, add it to column_names_mapping:

# config/initializers/avo.rb
Avo.configure do |config|
  # ...

  config.column_names_mapping = {
    published_at: {field: :date_time},
    body: {field: :markdown}
  }
end

If a database type should map to a different field, use column_types_mapping:

# config/initializers/avo.rb
Avo.configure do |config|
  # ...

  config.column_types_mapping = {
    jsonb: {field: :code, language: "json"},
    decimal: {field: :number, decimals: 2}
  }
end

Both merge on top of Avo's built-in mappings, so you only list the entries you want to change. Everything besides the field key is passed to the field as options.