Group Rails query into arrays by attribute

Question

Suppose I have these rows: (represented as JSON):

[
  { name: "Bob", age: 10 },
  { name: "Carl", age: 15 },
  { name: "Alice", age: 10 },
  { name: "Derek", age: 20 }
]

How can I, in Rails, group these by age? For example, I want something like this:

[
  { age: 10, objects: [
    { name: "Bob", age: 10 },
    { name: "Alice", age: 10 }
  ] },
  { age: 15, objects: [
    { name: "Carl", age: 15 }
  ] },
  { age: 20, objects: [
    { name: "Derek", age: 20 }
  ] },
]

Answer 1

Got it!

People.all.group_by(&:age)

Answer 2

If you're actually dealing with JSON:

people.group_by{|p| p['age'] }

If you're dealing with ActiveRecord models:

People.group('id, age')

Here there's additional documentation on grouping with ActiveRecord.