Joseph-Rance commented on code in PR #4773:
URL: https://github.com/apache/arrow-rs/pull/4773#discussion_r1342545617
##########
parquet_derive/README.md:
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@@ -77,16 +77,55 @@ 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 to read into
+let mut chunks = vec![ACompleteRecord{ ... }];
Review Comment:
Where do you want to initialise the structs? If we want to do it at the
start of the macro we would need the struct to derive default, which I think
might be problematic for some structs. I don't think we can very easily
initialise the struct with all the data we have already read because we read
them column by column. I can save the columns and then build the structs after
the entire file is read but this seems possibly overcomplicated compared to
just letting the user initialise the structs.
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