wjones127 opened a new issue, #6420:
URL: https://github.com/apache/arrow-rs/issues/6420
**Is your feature request related to a problem or challenge? Please describe
what you are trying to do.**
There is a nice example in the `StreamDecoder::decode` docs from reading
from a stream:
> ```rust
> fn print_stream<I>(src: impl Iterator<Item = Buffer>) -> Result<(),
ArrowError> {
> let mut decoder = StreamDecoder::new();
> for mut x in src {
> while !x.is_empty() {
> if let Some(x) = decoder.decode(&mut x)? {
> println!("{x:?}");
> }
> }
> }
> decoder.finish().unwrap();
> Ok(())
> }
> ```
https://docs.rs/arrow-ipc/latest/arrow_ipc/reader/struct.StreamDecoder.html#method.decode
**However, it doesn't show how to get the schema.** This would be useful if
someone wanted to construct a `RecordBatchReader` or
`SendableRecordBatchStream` from a stream of `Bytes` / `Buffer`. And it would
be particularly helpful in cases where there were zero batches but we still
wanted to get the schema.
**Describe the solution you'd like**
Minimally, it would be nice to do this:
```rust
impl StreamDecoder {
/// Return the schema, if decoded yet. Returns `None` if the schema
message
/// has yet to be decoded.
fn schema(&self) -> Option<SchemaRef> { ... }
}
```
But it might also be nice to parallel the decode method:
```rust
impl StreamDecoder {
/// Return the schema, if decoded yet. Returns `None` if the schema
message
/// has yet to be decoded.
fn decode_schema(&mut self, buffer: &mut Buffer) -> Option<SchemaRef> {
... }
}
```
**Describe alternatives you've considered**
I asked in Slack if there were other straight forward ways, but didn't see
anything easy from the suggestions.
https://the-asf.slack.com/archives/C01QUFS30TD/p1726636373388569
**Additional context**
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