datafusion-examples/examples/config_extension.rs

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//! This example demonstrates how to extend the DataFusion configs with custom extensions.

use datafusion::{
    common::{config::ConfigExtension, extensions_options},
    config::ConfigOptions,
};

extensions_options! {
    /// My own config options.
    pub struct MyConfig {
        /// Should "foo" be replaced by "bar"?
        pub foo_to_bar: bool, default = true

        /// How many "baz" should be created?
        pub baz_count: usize, default = 1337
    }
}

impl ConfigExtension for MyConfig {
    const PREFIX: &'static str = "my_config";
}

fn main() {
    // set up config struct and register extension
    let mut config = ConfigOptions::default();
    config.extensions.insert(MyConfig::default());

    // overwrite config default
    config.set("my_config.baz_count", "42").unwrap();

    // check config state
    let my_config = config.extensions.get::<MyConfig>().unwrap();
    assert!(my_config.foo_to_bar,);
    assert_eq!(my_config.baz_count, 42,);
}