nbruno commented on a change in pull request #9151:
URL: https://github.com/apache/arrow/pull/9151#discussion_r565612067
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File path: java/vector/src/main/codegen/templates/StructWriters.java
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@@ -184,6 +189,44 @@ public ListWriter list(String name) {
return writer;
}
+ @Override
+ public MapWriter map(String name) {
+ // returns existing writer
+ final FieldWriter writer = fields.get(handleCase(name));
+ Preconditions.checkNotNull(writer);
Review comment:
This should be following the paradigm for other complex types that
require arguments. In general, `foo(String name)` seems to be used to return an
existing writer when the given type requires arguments. The existing writer is
expected to have already been created by calling a same-named method with the
type's arguments.
For a Map, you need to send in keysSorted for us to be able to construct a
writer. There's other types that you need to specify some additional info in
order to be able to construct it (Duration needs a TimeUnit, Decimal needs
scale / precision). I am guessing that these methods are provided for
convenience, so the caller can do:
writer.decimal256("example", 2, 5).writeDecimal256(..)
// Now, they can reference that vector later on without constructing a
new writer:
writer.decimal256("example").writeDecimal256(..)
That's why this is returning an existing writer and failing otherwise.
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