What is an item writer?

The item writer is used by the item job to load every processed item.

It can be any class implementing ItemWriterInterface.

What types of item writers exists?

Built-in item writers:

JsonLinesWriter: write items as a json string each on a line of a file.
ChainWriter: write items on multiple item writers.
ConditionalWriter: will only write items that are matching your conditions.
DispatchEventsWriter: will dispatch events before and after writing.
LaunchJobForEachItemWriter: launch another job for each items.
LaunchJobForItemsBatchWriter: launch another job for each item batches.
NullWriter: do not write items.
RoutingWriter: route writing to different writer based on your logic.
SummaryWriter: write items to a job summary value.
TransformingWriter: perform items transformation before delegating to another writer.
CallbackWriter: delegate items write operations to a closure passed at construction.

Item writers from bridges:

From symfony/messenger bridge:
- DispatchEachItemAsMessageWriter: dispatch each item as a message in a bus.
From doctrine/dbal bridge:
- DoctrineDBALInsertWriter: write items by inserting in a table via a Doctrine Connection.
- DoctrineDBALUpsertWriter: write items by inserting/updating in a table via a Doctrine Connection.
From doctrine/persistence bridge:
- ObjectWriter: write items to any Doctrine ObjectManager.
From openspout/openspout bridge:
- FlatFileWriter: write items to any CSV/ODS/XLSX file.

Item writers for testing purpose:

InMemoryWriter: write in a private var which can be accessed afterward in your tests.
TestDebugWriter: dummy item writer that you can use in your unit tests.