Nested Transforms

When a transform's value is an array of transform objects instead of a string expression, it triggers a nested transformation. This allows you to recursively process sub-objects within the data.

How it works

A nested transform takes the current field's value (expected to be an object), applies the inner transforms to it, and assigns the result back to the field.

Example

Input

{
  "address": {
    "street": "123 main st",
    "city": "springfield"
  }
}

Output

{
  "address": {
    "street": "123 MAIN ST",
    "city": "SPRINGFIELD",
    "full": "123 MAIN ST, SPRINGFIELD"
  }
}

Transforms (JSON)

[
  {
    "address": [
      { "street": "upper(input.address.street)" },
      { "city": "upper(input.address.city)" },
      { "full": "derived.street + ', ' + derived.city" }
    ]
  }
]

Transforms (DDS)

address:
  street: upper(input.address.street)
  city: upper(input.address.city)
  full: derived.street + ', ' + derived.city

Nested context

Inside a nested transform:

• input still refers to the original root input
• derived starts as a clone of the nested object's value
• Path tracing automatically updates the derived state

Arrays of objects

Nested transforms also work on arrays of objects when used with the forEach transform:

[
  {
    "items": "input.items | forEach([{ priceWithTax: 'item.price * 1.1' }])"
  }
]

Limitations

• Each transform object must have exactly one key
• Nested transforms can be nested further (multi-level nesting)
• The merge method for nested transforms is automatically set to transforms_only