BETA: This component is mostly stable but breaking changes could still be made outside of major version releases if a fundamental problem with the component is found.
branch processor allows you to create a new request message via
a Bloblang mapping, execute a list of processors
on the request messages, and, finally, map the result back into the source
message using another mapping.
This is useful for preserving the original message contents when using processors that would otherwise replace the entire contents.
Metadata fields that are added to messages during branch processing will not be
automatically copied into the resulting message. In order to do this you should
explicitly declare in your
result_map either a wholesale copy with
meta = meta(), or selective copies with
meta foo = meta("bar") and so on.
request_map fails the child processors will not be executed.
If the child processors themselves result in an (uncaught) error then the
result_map will not be executed. If the
the message will remain unchanged. Under any of these conditions standard
error handling methods can be used in
order to filter, DLQ or recover the failed messages.
If the root of your request map is set to
deleted() then the branch
processors are skipped for the given message, this allows you to conditionally
A Bloblang mapping that describes how to create a request payload suitable for the child processors of this branch. If left empty then the branch will begin with an exact copy of the origin message (including metadata).
A list of processors to apply to mapped requests. When processing message batches the resulting batch must match the size and ordering of the input batch, therefore filtering, grouping should not be performed within these processors.
A Bloblang mapping that describes how the resulting messages from branched processing should be mapped back into the original payload. If left empty the origin message will remain unchanged (including metadata).
- HTTP Request
- Non Structured Results
- Lambda Function
- Conditional Caching
This example strips the request message into an empty body, grabs an HTTP
payload, and places the result back into the original message at the path
When the result of your branch processors is unstructured and you wish to simply set a resulting field to the raw output use the content function to obtain the raw bytes of the resulting message and then coerce it into your value type of choice:
This example maps a new payload for triggering a lambda function with an ID and username from the original message, and the result of the lambda is discarded, meaning the original message is unchanged.
This example caches a document by a message ID only when the type of the document is a foo: