A command line tool and library for generating serde-compatible Rust types from Avro schemas. The apache-avro crate, which is re-exported, provides a way to read and write Avro data with such types.
Download the latest release.
Available options rsgen-avro --help:
Generate Rust types from Avro schemas
Usage: rsgen-avro [OPTIONS] <GLOB_PATTERN> <OUTPUT_FILE>
Arguments:
<GLOB_PATTERN> Glob pattern to select Avro schema files
<OUTPUT_FILE> The file where Rust types will be written, '-' for stdout
Options:
--fmt Run rustfmt on the resulting <output-file>
--nullable Replace null fields with their default value when deserializing
--precision <P> Precision for f32/f64 default values that aren't round numbers [default: 3]
--union-deser Custom deserialization for apache-avro multi-valued union types
--chrono-dates Use chrono::NaiveDateTime for date/timestamps logical types
--derive-builders Derive builders for generated record structs
--impl-schemas <METHOD> Implement AvroSchema for generated record structs [default: none] [possible values: derive, copy-build-schema, none]
--extra-derives <DERIVES> Extract Derives for generated record structs, comma separated, e.g. `std::fmt::Display,std::string::ToString`
-h, --help Print help (see more with '--help')
-V, --version Print version
As a library, the basic usage is:
use rsgen_avro::{Source, Generator};
let raw_schema = r#"
{
"type": "record",
"name": "test",
"fields": [
{"name": "a", "type": "long", "default": 42},
{"name": "b", "type": "string"}
]
}
"#;
let source = Source::SchemaStr(&raw_schema);
let mut out = std::io::stdout();
let g = Generator::new().unwrap();
g.generate(&source, &mut out).unwrap();This will generate the following output:
#[derive(Debug, PartialEq, Eq, Clone, serde::Deserialize, serde::Serialize)]
pub struct Test {
#[serde(default = "default_test_a")]
pub a: i64,
pub b: String,
}
#[inline(always)]
fn default_test_a() -> i64 { 42 }
Various Schema sources can be used with Generator::generate(source, output) method:
pub enum Source<'a> {
Schema(&'a rsgen_avro::Schema), // Avro schema enum re-exported from `apache-avro`
Schemas(&'a [rsgen_avro::Schema]), // A slice of Avro schema enums
SchemaStr(&'a str), // Schema as a json string
GlobPattern(&'a str), // Glob pattern to select schema files
}Note also that the Generator can be customized with a builder:
let generator = rsgen_avro::Generator::builder()
.precision(2)
.build()
.unwrap();See GeneratorBuilder documentation for all available options.
- Avro schema
namespacefields are ignored, therefore record names within a schema (and across schemas) must not conflict (i.e. must be unique). - Rust
Option<T>are supported through Avro unions having"null"in their first position only (See #39)