# INPUT_NEEDS_KEY

> newRows() on an input that has no key

**Error** · category **project** (the project has a mistake in an asset file, croft.json or the command line) · exit **2** (invalid project or usage)

NewRows() on an input that has no key.

An incremental TypeScript transform reads its inputs with newRows(), which hands over each input row once and
remembers where it stopped as (\_loaded_at, key): the stamp of the last row it processed, and that row's key.
One write stamps every row it changes with the same \_loaded_at, so the key is what tells those rows apart. An
input without a key gives newRows() nothing to remember its place by.

What to do, one of:
- Give the input a key: key: "id" in its TS config, or -- key: id in its SQL header. Pick the column, or
  columns, that identify a row; croft then checks that they are unique and never NULL.
- Read that input with rows() or ctx.query() instead, when the transform only looks things up in it.

croft validate reports this before a run, for the newRows("name") calls it can see in the code; a run reports
it when the code first calls newRows() on the input.

The same page is in the CLI: `croft docs INPUT_NEEDS_KEY`.

Source: https://croft.zabaca.com/docs/reference/errors/input-needs-key/