Trait RowExtractExt

pub trait RowExtractExt: Sealed {
    // Required methods
    fn extract_once<'row, T>(&'row self) -> T
       where T: Extract<'row>;
    fn extract<'row, T>(
        &'row self,
        columns: &mut Option<<T as Columns>::Columns>,
    ) -> T
       where T: Extract<'row>;
    fn extract_with_columns<'row, T>(
        &'row self,
        columns: &<T as Columns>::Columns,
    ) -> T
       where T: Extract<'row>;
}

Extension trait for extracting from a Row.

Required Methods

fn extract_once<'row, T>(&'row self) -> T

where T: Extract<'row>,

Extracts an instance of T from this Row.

This is equivalent to T::extract_once(self).

Panics

Panics if Extract::extract_once panics.

Examples

#[derive(Columns, Extract)]
struct User<'a> {
    id: i32,
    name: &'a str,
}

fn map_user(row: &Row) -> User<'_> {
    row.extract_once()
}

fn extract<'row, T>( &'row self, columns: &mut Option<<T as Columns>::Columns>, ) -> T

where T: Extract<'row>,

Extracts an instance of T from this Row, memorizing the mapping between fields and columns.

This is equivalent to T::extract(columns, self).

Panics

Panics if Extract::extract panics.

Examples

#[derive(Columns, Extract)]
struct User<'a> {
    id: i32,
    name: &'a str,
}

fn map_users(rows: &[Row]) -> Vec<User<'_>> {
    let mut columns = None;
    rows.iter().map(|row| row.extract(&mut columns)).collect()
}

fn extract_with_columns<'row, T>( &'row self, columns: &<T as Columns>::Columns, ) -> T

where T: Extract<'row>,

Extracts an instance of T from this Row and a mapping between the fields and columns.

This is equivalent to T::extract_with_columns(columns, self).

Panics

Panics if Extract::extract_with_columns panics.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl RowExtractExt for Row

fn extract_once<'row, T: Extract<'row>>(&'row self) -> T

fn extract<'row, T>( &'row self, columns: &mut Option<<T as Columns>::Columns>, ) -> T

where T: Extract<'row>,

fn extract_with_columns<'row, T>( &'row self, columns: &<T as Columns>::Columns, ) -> T

where T: Extract<'row>,

Implementors