Struct PassedRef

#[repr(C)]
pub struct PassedRef<T: 'static> { /* private fields */ }

Pass arbitrary values through SQLite.

Values of this type can be passed into SQL queries and returned by SQL functions, and later retrieved using ValueRef::get_ref. SQLite takes ownership of the stored value, and does not provide any mechanism for getting a PassedRef from a query result, so this feature is primarily useful for passing values into SQL, or between application-defined functions.

This mechanism relies on std::any::Any to ensure type safety, which requires that values are 'static. If you want to transfer a reference through a PassedRef, use a shared pointer like std::rc::Rc.

This feature requires SQLite 3.20.0. On earlier versions of SQLite, returning a PassedRef object from an application-defined function has no effect. If supporting older versions of SQLite is required, UnsafePtr can be used instead.

Examples

This example shows produce_ref returning a PassedRef which is later consumed by consume_ref.

use sqlite3_ext::{PassedRef, function::Context, Result, ValueRef};

fn produce_ref(ctx: &Context, args: &mut [&mut ValueRef]) -> PassedRef<String> {
    let val = "owned string".to_owned();
    PassedRef::new(val)
}

fn consume_ref(ctx: &Context, args: &mut [&mut ValueRef]) -> Result<()> {
    let val = args[0].get_ref::<String>().unwrap();
    assert_eq!(val, "owned string");
    Ok(())
}

Implementations

impl<T: 'static> PassedRef<T>

pub fn new(value: T) -> PassedRef<T>

Create a new PassedRef containing the value.

Trait Implementations

impl<T: 'static> Debug for PassedRef<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<T: 'static> ToParam for PassedRef<T>

Sets the parameter to NULL with this value as an associated pointer.

fn bind_param(self, stmt: &mut Statement, pos: i32) -> Result<()>

Bind this value to the prepared Statement at the provided position.

impl<T: 'static> ToContextResult for PassedRef<T>

Sets the context result to NULL with this value as an associated pointer.