## wiring.build_file_writer()


Return a writer that writes the error rows to a parquet file under `error_rows_dir`.


Usage

``` python
wiring.build_file_writer(
    context,
    error_rows_key,
    error_rows_dir,
)
```


Use it in a direct invocation, where [build_io_manager_writer](wiring.build_io_manager_writer.md#dagster_dataframely.wiring.build_io_manager_writer) raises because there is no step. The file is at `get_error_rows_path(error_rows_key, error_rows_dir, context.partition_key)`.


## Parameters


`context: dg.AssetExecutionContext`  
The context the asset was invoked with. The writer reads only its partition key, so a context from `dg.build_asset_context()` works unbound. Without a partition key, the rows go to the unpartitioned path.

`error_rows_key: dg.AssetKey`  
The key the writer writes under, such as the one [get_error_rows_key](wiring.get_error_rows_key.md#dagster_dataframely.wiring.get_error_rows_key) returns.

`error_rows_dir: UPath | Path | str`  
The directory the file goes under. Any path `UPath` accepts.


## Returns


`ErrorRowsWriter`  
A writer that takes the error rows and returns the file's path as a string.


## Raises


`dg.DagsterInvariantViolationError`  
The context has a partition range and no partition key. The error rows do not record which partition each row came from, so they cannot be split into one file per partition.


## Examples


``` python
import tempfile

import dagster as dg

import dagster_dataframely as dd
from dagster_dataframely.data import OrdersSchema, marketplace_orders

error_rows_dir = tempfile.mkdtemp()
write = dd.wiring.build_file_writer(
    dg.build_asset_context(),
    dd.wiring.get_error_rows_key(dg.AssetKey("orders")),
    error_rows_dir,
)
_, failure = OrdersSchema.filter(marketplace_orders, cast=False)
write(dd.wiring.get_error_rows(OrdersSchema, failure)).removeprefix(error_rows_dir)
```


    '/orders__error_rows.parquet'