autowrap

Ruby

rel.autowrap
rel.autowrap(split: "_")
rel.autowrap(postprocessor: :nil)

TypeScript

rel.autowrap()
rel.autowrap({ split: "_" })

Problem

Automatically structure flat tuples into nested objects based on attribute naming conventions.

Example: I have flat results from a SQL join with columns like customer_id, customer_name, and I want to nest them into a customer object.

Description

The autowrap operator transforms flat tuples into nested structures by detecting naming patterns. Attributes with names like prefix_suffix are automatically grouped under the prefix as a nested object.

This is particularly useful when working with:

• Results from SQL joins that produce flat column names
• Data that needs to be serialized to JSON with nested objects
• Denormalized data that should be re-structured

Ruby

Options:

Option	Description
split	The separator to use for detecting nesting (default: "_")
postprocessor	How to handle all-nil nested objects: :none (default), :nil (replace with nil), or :delete (remove attribute)

TypeScript

Options:

Option	Description
split	The separator to use for detecting nesting (default: "_")

Requirements

No special requirements. Works on any relation.

Examples

Basic autowrap

Ruby

flat = Bmg::Relation.new([
  { id: 1, name: "Order 1", customer_id: 100, customer_name: "Alice", customer_city: "London" },
  { id: 2, name: "Order 2", customer_id: 101, customer_name: "Bob", customer_city: "Paris" }
])

flat.autowrap.to_a

=>
[{:id=>1, :name=>"Order 1", :customer=>{:id=>100, :name=>"Alice", :city=>"London"}},
 {:id=>2, :name=>"Order 2", :customer=>{:id=>101, :name=>"Bob", :city=>"Paris"}}]

TypeScript

const flat = Bmg([
  { id: 1, name: "Order 1", customer_id: 100, customer_name: "Alice", customer_city: "London" },
  { id: 2, name: "Order 2", customer_id: 101, customer_name: "Bob", customer_city: "Paris" }
])

flat.autowrap().toArray()

// =>
// [{ id: 1, name: "Order 1", customer: { id: 100, name: "Alice", city: "London" } },
//  { id: 2, name: "Order 2", customer: { id: 101, name: "Bob", city: "Paris" } }]

Multi-level nesting

Autowrap supports multiple levels of nesting:

Ruby

deep = Bmg::Relation.new([
  { id: 1, ship_address_city: "London", ship_address_zip: "SW1", ship_address_country_name: "UK" }
])

deep.autowrap.to_a

=>
[{:id=>1, :ship=>{:address=>{:city=>"London", :zip=>"SW1", :country=>{:name=>"UK"}}}}]

TypeScript

const deep = Bmg([
  { id: 1, ship_address_city: "London", ship_address_zip: "SW1", ship_address_country_name: "UK" }
])

deep.autowrap().toArray()

// =>
// [{ id: 1, ship: { address: { city: "London", zip: "SW1", country: { name: "UK" } } } }]

Comparison with unwrap

autowrap and unwrap are conceptual inverses:

• autowrap - Detects naming patterns and creates nested objects
• unwrap - Flattens nested objects back to top-level attributes

However, they’re not perfect inverses because autowrap uses naming conventions while unwrap simply merges keys.