Enum extendr_api::wrapper::nullable::Nullable[][src]

pub enum Nullable<T> {
    NotNull(T),
    Null,
}
Expand description

Wrapper for handling potentially NULL values.

use extendr_api::prelude::*;
test! {
    use extendr_api::wrapper::Nullable::*;

    // Plain integer.
    let s1 = r!(1);
    let n1 = <Nullable<i32>>::from_robj(&s1)?;
    assert_eq!(n1, NotNull(1));

    // NA integer - error.
    let sna = r!(NA_INTEGER);
    assert_eq!(<Nullable<i32>>::from_robj(&sna).is_err(), true);

    // NA integer - option gives none.
    assert_eq!(<Nullable<Option<i32>>>::from_robj(&sna)?, NotNull(None));

    // NULL object.
    let snull = r!(NULL);
    let nnull = <Nullable<i32>>::from_robj(&snull)?;
    assert_eq!(nnull, Null);

    assert_eq!(r!(Nullable::<i32>::Null), r!(NULL));
    assert_eq!(r!(Nullable::<i32>::NotNull(1)), r!(1));
}

Variants

NotNull(T)

Tuple Fields of NotNull

0: T
Null

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Convert a rust object to NULL or another type.

use extendr_api::prelude::*;
test! {
    assert_eq!(r!(Nullable::<i32>::Null), r!(NULL));
    assert_eq!(r!(Nullable::<i32>::NotNull(1)), r!(1));
}

Convert an object that may be null to a rust type.

use extendr_api::prelude::*;
test! {
    let s1 = r!(1);
    let n1 = <Nullable<i32>>::from_robj(&s1)?;
    assert_eq!(n1, Nullable::NotNull(1));
    let snull = r!(NULL);
    let nnull = <Nullable<i32>>::from_robj(&snull)?;
    assert_eq!(nnull, Nullable::Null);
}

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Performs the conversion.

Performs the conversion.

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.