Background

When a file has a record length field, but neither mechanisms work:

• Fixed length does not work because record lengths are variable for the file.
• Record field expression is not rich enough to express the relation between field values and record lengths.
• Record length mapping is not sufficient because the mapping is too complex

and

• Custom record extractor is too hard to implement

then a custom record length mapper can work.

You can use custom logic to map values from the specified field to the record length value.

Feature

Add the ability to implement custom field value to record length mapper.

Example [Optional]

.option("record_length_field", "my_length_field")
.option("record_length_custom_mapper", "com.example.MyMapper")

Proposed Solution [Optional]

To be added...