tustvold commented on code in PR #4773:
URL: https://github.com/apache/arrow-rs/pull/4773#discussion_r1375489626
##########
parquet_derive/README.md:
##########
@@ -71,22 +71,61 @@ let mut row_group = writer.next_row_group().unwrap();
let chunks = vec![ACompleteRecord{...}];
// The derived `RecordWriter` takes over here
-(&chunks[..]).write_to_row_group(&mut row_group);
+chunks.write_to_row_group(&mut row_group);
writer.close_row_group(row_group).unwrap();
writer.close().unwrap();
```
+Example usage of deriving a `RecordReader` for your struct:
+
+```rust
+use parquet::file::{serialized_reader::SerializedFileReader,
reader::FileReader};
+use parquet_derive::ParquetRecordReader;
+
+#[derive(ParquetRecordReader)]
+struct ACompleteRecord {
+ pub a_bool: bool,
+ pub a_string: String,
+ pub i16: i16,
+ pub i32: i32,
+ pub u64: u64,
+ pub isize: isize,
+ pub float: f32,
+ pub double: f64,
+ pub now: chrono::NaiveDateTime,
+ pub byte_vec: Vec<u8>,
+}
+
+// Initialize your parquet file
+let reader = SerializedFileReader::new(file).unwrap();
+let mut row_group = reader.get_row_group(0).unwrap();
+
+// create your records vector to read into
+let mut chunks: Vec<ACompleteRecord> = Vec::new();
+
+// The derived `RecordReader` takes over here
+chunks.read_from_row_group(&mut *row_group, 1).unwrap();
+```
+
## Features
- [x] Support writing `String`, `&str`, `bool`, `i32`, `f32`, `f64`, `Vec<u8>`
- [ ] Support writing dictionaries
- [x] Support writing logical types like timestamp
-- [x] Derive definition_levels for `Option`
-- [ ] Derive definition levels for nested structures
+- [x] Derive definition_levels for `Option` for writing
+- [ ] Derive definition levels for nested structures for writing
- [ ] Derive writing tuple struct
- [ ] Derive writing `tuple` container types
+- [x] Support reading `String`, `&str`, `bool`, `i32`, `f32`, `f64`, `Vec<u8>`
+- [ ] Support reading/writing dictionaries
+- [x] Support reading/writing logical types like timestamp
+- [ ] Derive definition_levels for `Option` for reading
+- [ ] Derive definition levels for nested structures for reading
Review Comment:
Lines 116 and 117 are correct, the writer derives levels from the input
data, the reader, however, needs to do the opposite :smile:
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