mirror of
https://github.com/launchbadge/sqlx.git
synced 2025-12-30 05:11:13 +00:00
0d0dddf1d0
Add bounds such that cyclic associated types are equal to themselves. ``` <T as Connection>::Database as Database>::Connection == T <T as ConnectOptions>::Connection as Connection>::Options == T <T as Row>::Database as Database>::Row == T <T as Column>::Database as Database>::Column == T <T as Value>::Database as Database>::Value == T ```
114 lines
3.4 KiB
Rust
114 lines
3.4 KiB
Rust
use crate::database::Database;
|
|
use crate::decode::Decode;
|
|
use crate::error::{mismatched_types, Error};
|
|
use crate::type_info::TypeInfo;
|
|
use crate::types::Type;
|
|
use std::borrow::Cow;
|
|
|
|
/// An owned value from the database.
|
|
pub trait Value {
|
|
type Database: Database<Value = Self>;
|
|
|
|
/// Get this value as a reference.
|
|
fn as_ref(&self) -> <Self::Database as Database>::ValueRef<'_>;
|
|
|
|
/// Get the type information for this value.
|
|
fn type_info(&self) -> Cow<'_, <Self::Database as Database>::TypeInfo>;
|
|
|
|
/// Returns `true` if the SQL value is `NULL`.
|
|
fn is_null(&self) -> bool;
|
|
|
|
/// Decode this single value into the requested type.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Panics if the value cannot be decoded into the requested type.
|
|
/// See [`try_decode`](Self::try_decode) for a non-panicking version.
|
|
///
|
|
#[inline]
|
|
fn decode<'r, T>(&'r self) -> T
|
|
where
|
|
T: Decode<'r, Self::Database> + Type<Self::Database>,
|
|
{
|
|
self.try_decode::<T>().unwrap()
|
|
}
|
|
|
|
/// Decode this single value into the requested type.
|
|
///
|
|
/// Unlike [`decode`](Self::decode), this method does not check that the type of this
|
|
/// value is compatible with the Rust type and blindly tries to decode the value.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Panics if the value cannot be decoded into the requested type.
|
|
/// See [`try_decode_unchecked`](Self::try_decode_unchecked) for a non-panicking version.
|
|
///
|
|
#[inline]
|
|
fn decode_unchecked<'r, T>(&'r self) -> T
|
|
where
|
|
T: Decode<'r, Self::Database>,
|
|
{
|
|
self.try_decode_unchecked::<T>().unwrap()
|
|
}
|
|
|
|
/// Decode this single value into the requested type.
|
|
///
|
|
/// # Errors
|
|
///
|
|
/// * [`Decode`] if the value could not be decoded into the requested type.
|
|
///
|
|
/// [`Decode`]: Error::Decode
|
|
///
|
|
#[inline]
|
|
fn try_decode<'r, T>(&'r self) -> Result<T, Error>
|
|
where
|
|
T: Decode<'r, Self::Database> + Type<Self::Database>,
|
|
{
|
|
if !self.is_null() {
|
|
let ty = self.type_info();
|
|
|
|
if !ty.is_null() && !T::compatible(&ty) {
|
|
return Err(Error::Decode(mismatched_types::<Self::Database, T>(&ty)));
|
|
}
|
|
}
|
|
|
|
self.try_decode_unchecked()
|
|
}
|
|
|
|
/// Decode this single value into the requested type.
|
|
///
|
|
/// Unlike [`try_decode`](Self::try_decode), this method does not check that the type of this
|
|
/// value is compatible with the Rust type and blindly tries to decode the value.
|
|
///
|
|
/// # Errors
|
|
///
|
|
/// * [`Decode`] if the value could not be decoded into the requested type.
|
|
///
|
|
/// [`Decode`]: Error::Decode
|
|
///
|
|
#[inline]
|
|
fn try_decode_unchecked<'r, T>(&'r self) -> Result<T, Error>
|
|
where
|
|
T: Decode<'r, Self::Database>,
|
|
{
|
|
T::decode(self.as_ref()).map_err(Error::Decode)
|
|
}
|
|
}
|
|
|
|
/// A reference to a single value from the database.
|
|
pub trait ValueRef<'r>: Sized {
|
|
type Database: Database;
|
|
|
|
/// Creates an owned value from this value reference.
|
|
///
|
|
/// This is just a reference increment in PostgreSQL and MySQL and thus is `O(1)`. In SQLite,
|
|
/// this is a copy.
|
|
fn to_owned(&self) -> <Self::Database as Database>::Value;
|
|
|
|
/// Get the type information for this value.
|
|
fn type_info(&self) -> Cow<'_, <Self::Database as Database>::TypeInfo>;
|
|
|
|
/// Returns `true` if the SQL value is `NULL`.
|
|
fn is_null(&self) -> bool;
|
|
}
|