I have a JSON in the shape

[
  {
    a:1,
    b: [2,3]
  },
  {
    a:4,
    b: [5,6]
  }
]

That I want to transform in the shape

[
  [
    {
      a: 1,
      b: 2,
    },
    {
      a: 1,
      b: 3,
    },
  ],
  [
    {
      a: 4,
      b: 5,
    },
    {
      a: 4,
      b: 6,
    },
  ],
]

That is I want to bring the value of the field a inside the array.

how can I do this with jq?

CodePudding user response：

You could iterate over the items using variable binding with as.

Then either update .b to have the value of its items using the update operator |=:

jq 'map([.b[] as $b | .b |= $b])'

Demo

Or create completely new objects from data collected:

jq 'map(.a as $a | [.b[] as $b | {$a,$b}])'

Demo

[
  [
    {
      "a": 1,
      "b": 2
    },
    {
      "a": 1,
      "b": 3
    }
  ],
  [
    {
      "a": 4,
      "b": 5
    },
    {
      "a": 4,
      "b": 6
    }
  ]
]

CodePudding user response：

Try this :

jq 'map([{a,b:.b[]}])'

As @pmf pointed out, you can also update object :

jq 'map([.b=.b[]])'