datafusion-examples/examples/dataframe/main.rs

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//! # These are core DataFrame API usage
//!
//! These examples demonstrate core DataFrame API usage.
//!
//! ## Usage
//! ```bash
//! cargo run --example dataframe -- [all|dataframe|deserialize_to_struct|cache_factory]
//! ```
//!
//! Each subcommand runs a corresponding example:
//! - `all` — run all examples included in this module
//!
//! - `cache_factory`
//!   (file: cache_factory.rs, desc: Custom lazy caching for DataFrames using `CacheFactory`)
//
//! - `dataframe`
//!   (file: dataframe.rs, desc: Query DataFrames from various sources and write output)
//!
//! - `deserialize_to_struct`
//!   (file: deserialize_to_struct.rs, desc: Convert Arrow arrays into Rust structs)

mod cache_factory;
mod dataframe;
mod deserialize_to_struct;

use datafusion::error::{DataFusionError, Result};
use strum::{IntoEnumIterator, VariantNames};
use strum_macros::{Display, EnumIter, EnumString, VariantNames};

#[derive(EnumIter, EnumString, Display, VariantNames)]
#[strum(serialize_all = "snake_case")]
enum ExampleKind {
    All,
    Dataframe,
    DeserializeToStruct,
    CacheFactory,
}

impl ExampleKind {
    const EXAMPLE_NAME: &str = "dataframe";

    fn runnable() -> impl Iterator<Item = ExampleKind> {
        ExampleKind::iter().filter(|v| !matches!(v, ExampleKind::All))
    }

    async fn run(&self) -> Result<()> {
        match self {
            ExampleKind::All => {
                for example in ExampleKind::runnable() {
                    println!("Running example: {example}");
                    Box::pin(example.run()).await?;
                }
            }
            ExampleKind::Dataframe => {
                dataframe::dataframe_example().await?;
            }
            ExampleKind::DeserializeToStruct => {
                deserialize_to_struct::deserialize_to_struct().await?;
            }
            ExampleKind::CacheFactory => {
                cache_factory::cache_dataframe_with_custom_logic().await?;
            }
        }
        Ok(())
    }
}

#[tokio::main]
async fn main() -> Result<()> {
    let usage = format!(
        "Usage: cargo run --example {} -- [{}]",
        ExampleKind::EXAMPLE_NAME,
        ExampleKind::VARIANTS.join("|")
    );

    let example: ExampleKind = std::env::args()
        .nth(1)
        .unwrap_or_else(|| ExampleKind::All.to_string())
        .parse()
        .map_err(|_| DataFusionError::Execution(format!("Unknown example. {usage}")))?;

    example.run().await
}