clickhouse-arrow 0.1.1

ClickHouse Arrow Client for Rust
Documentation 
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use std::borrow::Cow;

use crate::{Error, FromSql, Result, Row, ToSql, Type, Value};

/// A single column row
#[derive(Clone, Debug, Default)]
pub struct UnitValue<T: FromSql + ToSql>(pub T);

impl<T: FromSql + ToSql> Row for UnitValue<T> {
    const COLUMN_COUNT: Option<usize> = Some(1);

    fn column_names() -> Option<Vec<Cow<'static, str>>> { None }

    fn to_schema() -> Option<Vec<(String, Type, Option<Value>)>> { None }

    fn deserialize_row(map: Vec<(&str, &Type, Value)>) -> Result<Self> {
        if map.is_empty() {
            return Err(Error::MissingField("<unit>"));
        }
        let item = map.into_iter().next().unwrap();
        T::from_sql(item.1, item.2).map(UnitValue)
    }

    fn serialize_row(
        self,
        type_hints: &[(String, Type)],
    ) -> Result<Vec<(Cow<'static, str>, Value)>> {
        Ok(vec![(Cow::Borrowed("_"), self.0.to_sql(type_hints.iter().map(|(_, t)| t).next())?)])
    }
}