# `type.batch_capture_not_storable`

A batch saves a value that can't be stored.

Area 12, [Jobs and events](../topics/jobs-and-events.md); not declinable; the next step is usually the agent's.

What a run saves (`from:`'s query's arguments, what `each:` and
`finished:` capture, and `key:`) is kept as its type's JSON, so the run can
resume after a crash or a deploy; a value an entity field couldn't hold,
such as a request's `Input`, is refused, naming it:


```jadpo
action mark_on(item: Item, page: ItemPage) -> Unit {
    assert item.seen == item.seen
}

action sweep_shelf(page: ItemPage) -> BatchRun {
    return batches.each(from: items(page), each: item -> mark_on(item, page))
}
```

```text
error: `batches.each` can't save `page`
 --> main.jadpo:6:72
  |
6 |     return batches.each(from: items(page), each: item -> mark_on(item, page))
  |                                                                        ^^^^ `ItemPage` has no stored form
  reason: What `each:` captures is worked out when the run starts and saved with it, as its type's JSON, so the run can resume after a crash or a deploy; `page` is `ItemPage`, an `Input`, the shape a request arrives in, where a record keeps an `Object`.
  next: Pass something an entity field could hold instead, such as the `id` that finds `page` (agent)
  rule: type.batch_capture_not_storable
  help: https://jadpo.dev/docs/errors/type.batch_capture_not_storable

check failed: 1 error, 2 files
```