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# Parquet Derive

A crate for deriving `RecordWriter` for arbitrary, _simple_ structs. This does not generate writers for arbitrarily nested
structures. It only works for primitives and a few generic structures and
various levels of reference. Please see features checklist for what is currently
supported.

Derive also has some support for the chrono time library. You must must enable the `chrono` feature to get this support.

## Usage

Add this to your Cargo.toml:

```toml
[dependencies]
parquet = "29.0.0"
parquet_derive = "29.0.0"
```

and this to your crate root:

```rust
extern crate parquet;
#[macro_use] extern crate parquet_derive;
```

Example usage of deriving a `RecordWriter` for your struct:

```rust
use parquet;
use parquet::record::RecordWriter;

#[derive(ParquetRecordWriter)]
struct ACompleteRecord<'a> {
    pub a_bool: bool,
    pub a_str: &'a str,
    pub a_string: String,
    pub a_borrowed_string: &'a String,
    pub maybe_a_str: Option<&'a str>,
    pub magic_number: i32,
    pub low_quality_pi: f32,
    pub high_quality_pi: f64,
    pub maybe_pi: Option<f32>,
    pub maybe_best_pi: Option<f64>,
}

// Initialize your parquet file
let mut writer = SerializedFileWriter::new(file, schema, props).unwrap();
let mut row_group = writer.next_row_group().unwrap();

// Build up your records
let chunks = vec![ACompleteRecord{...}];

// The derived `RecordWriter` takes over here
(&chunks[..]).write_to_row_group(&mut row_group);

writer.close_row_group(row_group).unwrap();
writer.close().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
- [ ] Derive writing tuple struct
- [ ] Derive writing `tuple` container types

## Requirements

- Same as `parquet-rs`

## Test

Testing a `*_derive` crate requires an intermediate crate. Go to `parquet_derive_test` and run `cargo test` for
unit tests.

## Docs

To build documentation, run `cargo doc --no-deps`.
To compile and view in the browser, run `cargo doc --no-deps --open`.

## License

Licensed under the Apache License, Version 2.0: http://www.apache.org/licenses/LICENSE-2.0.
