# `type.file_read_too_large`

A whole read of a file field that can hold more than 10 MB.

Area 16, [Built-in services](../topics/built-in-services.md); not declinable; the next step is usually the agent's.

`store.read` reads a whole file into memory, so it reads a field only
when its `max_size:` is 10 MB or less; a file's rows, of any size, are
read a batch at a time by the format helpers:



```jadpo
use app { sheets }
use bakery/entities { PriceSheet }

/// A price sheet's bytes, whole.
action sheet_bytes(sheet: PriceSheet.sheet) -> FileContents {
    return sheets.read(sheet)
}
```

```text
error: `sheets.read` can't read `PriceSheet.sheet` whole
 --> domains/bakery/actions/sheet_bytes.jadpo:6:24
  |
6 |     return sheets.read(sheet)
  |                        ^^^^^ holds up to 50 MB
  reason: `sheets.read` reads a whole file into memory, for passing its bytes on, so it reads at most 10 MB; `PriceSheet.sheet` holds up to 50 MB. A file's rows, of any size, are read a batch at a time by the format helpers (`csv.read`, `tsv.read`, `json_lines.read`).
  next: Read `PriceSheet.sheet`'s rows with a format helper, such as `csv.read`, or keep its `max_size:` at 10 MB or less if `sheets.read` is what it needs (agent)
  rule: type.file_read_too_large
  help: https://jadpo.dev/docs/errors/type.file_read_too_large

check failed: 1 error, 3 files
```