Trait FromSql

Source

pub trait FromSql<A, DB: Backend>: Sized {
    // Required method
    fn from_sql(bytes: Option<&DB::RawValue>) -> Result<Self>;
}

Expand description

Deserialize a single field of a given SQL type.

When possible, implementations of this trait should prefer to use an existing implementation, rather than reading from bytes. (For example, if you are implementing this for an enum which is represented as an integer in the database, prefer i32::from_sql(bytes) over reading from bytes directly)

Types which implement this trait should also have #[derive(FromSqlRow)]

§Backend specific details

For PostgreSQL, the bytes will be sent using the binary protocol, not text.
For SQLite, the actual type of DB::RawValue is private API. All implementations of this trait must be written in terms of an existing primitive.
For MySQL, the value of bytes will depend on the return value of type_metadata for the given SQL type. See MysqlType for details.
For third party backends, consult that backend’s documentation.

§Examples

Most implementations of this trait will be defined in terms of an existing implementation.

#[repr(i32)]
#[derive(Debug, Clone, Copy)]
pub enum MyEnum {
    A = 1,
    B = 2,
}

impl<DB> FromSql<Integer, DB> for MyEnum
where
    DB: Backend,
    i32: FromSql<Integer, DB>,
{
    fn from_sql(bytes: Option<&DB::RawValue>) -> deserialize::Result<Self> {
        match i32::from_sql(bytes)? {
            1 => Ok(MyEnum::A),
            2 => Ok(MyEnum::B),
            x => Err(format!("Unrecognized variant {}", x).into()),
        }
    }
}

Required Methods§

Source

fn from_sql(bytes: Option<&DB::RawValue>) -> Result<Self>

See the trait documentation.

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.

Trait FromSqlCopy item path

§Backend specific details

§Examples

Required Methods§

fn from_sql(bytes: Option<&DB::RawValue>) -> Result<Self>

Dyn Compatibility§

Implementations on Foreign Types§

impl FromSql<Cidr, Pg> for IpNetwork

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Inet, Pg> for IpNetwork

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Json, Pg> for Value

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Jsonb, Pg> for Value

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<MacAddr, Pg> for [u8; 6]

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Oid, Pg> for u32

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Timestamptz, Pg> for DateTime<Utc>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Timestamptz, Pg> for NaiveDateTime

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Uuid, Pg> for Uuid

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Uuid, Pg> for Uuid

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Bool, Pg> for bool

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Date, Pg> for NaiveDate

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Time, Pg> for NaiveTime

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Timestamp, Pg> for NaiveDateTime

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl FromSql<Timestamp, Pg> for SystemTime

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

impl<'a, T, ST, DB> FromSql<ST, DB> for Cow<'a, T>where T: 'a + ToOwned + ?Sized, DB: Backend, T::Owned: FromSql<ST, DB>,

fn from_sql(bytes: Option<&DB::RawValue>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

fn from_sql(bytes: Option<&[u8]>) -> Result<Self>

Trait FromSql

impl<'a, T, ST, DB> FromSql<ST, DB> for Cow<'a, T>
where T: 'a + ToOwned + ?Sized, DB: Backend, T::Owned: FromSql<ST, DB>,