pub trait Decode<'r, DB: Database>: Sized {
    // Required method
    fn decode(
        value: <DB as HasValueRef<'r>>::ValueRef
    ) -> Result<Self, BoxDynError>;
}
Expand description

A type that can be decoded from the database.

How can I implement Decode?

A manual implementation of Decode can be useful when adding support for types externally to SQLx.

The following showcases how to implement Decode to be generic over Database. The implementation can be marginally simpler if you remove the DB type parameter and explicitly use the concrete ValueRef and TypeInfo types.

struct MyType;

// DB is the database driver
// `'r` is the lifetime of the `Row` being decoded
impl<'r, DB: Database> Decode<'r, DB> for MyType
where
    // we want to delegate some of the work to string decoding so let's make sure strings
    // are supported by the database
    &'r str: Decode<'r, DB>
{
    fn decode(
        value: <DB as HasValueRef<'r>>::ValueRef,
    ) -> Result<MyType, Box<dyn Error + 'static + Send + Sync>> {
        // the interface of ValueRef is largely unstable at the moment
        // so this is not directly implementable

        // however, you can delegate to a type that matches the format of the type you want
        // to decode (such as a UTF-8 string)

        let value = <&str as Decode<DB>>::decode(value)?;

        // now you can parse this into your type (assuming there is a `FromStr`)

        Ok(value.parse()?)
    }
}

Required Methods§

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fn decode(value: <DB as HasValueRef<'r>>::ValueRef) -> Result<Self, BoxDynError>

Decode a new value of this type using a raw value from the database.

Implementations on Foreign Types§

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impl Decode<'_, Mssql> for Vec<u8>

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impl Decode<'_, Mssql> for i8

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impl Decode<'_, Mssql> for NaiveDateTime

Decodes DateTime2N values received from the server

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impl Decode<'_, MySql> for Uuid

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impl<'r> Decode<'r, Postgres> for NaiveDate

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r, T> Decode<'r, Postgres> for Vec<T>where T: for<'a> Decode<'a, Postgres> + Type<Postgres>,

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for i8

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impl Decode<'_, Mssql> for NaiveDate

Decodes Date values received from the server

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impl<'r> Decode<'r, Sqlite> for bool

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impl Decode<'_, MySql> for f64

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impl Decode<'_, Mssql> for String

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impl Decode<'_, MySql> for u64

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impl<'r, T1, T2, T3, T4, T5, T6, T7, T8> Decode<'r, Postgres> for (T1, T2, T3, T4, T5, T6, T7, T8)where T1: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T2: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T3: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T4: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T5: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T6: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T7: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T8: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>,

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for DateTime<Utc>

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impl<'r, T1, T2, T3, T4, T5, T6, T7, T8, T9> Decode<'r, Postgres> for (T1, T2, T3, T4, T5, T6, T7, T8, T9)where T1: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T2: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T3: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T4: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T5: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T6: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T7: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T8: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T9: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>,

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for i16

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impl Decode<'_, Postgres> for Decimal

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Postgres> for DateTime<Local>

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r, T1, T2, T3> Decode<'r, Postgres> for (T1, T2, T3)where T1: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T2: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T3: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>,

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Any> for &'r [u8]where &'r [u8]: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for i32

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impl Decode<'_, Postgres> for BitVec

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Postgres> for Cow<'r, str>

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Any> for DateTime<Local>where DateTime<Local>: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, MySql> for OffsetDateTime

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impl<'r> Decode<'r, Sqlite> for NaiveTime

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impl Decode<'_, MySql> for i8

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impl<'r> Decode<'r, Sqlite> for &'r [u8]

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impl<'r, T, const N: usize> Decode<'r, Postgres> for [T; N]where T: for<'a> Decode<'a, Postgres> + Type<Postgres>,

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for u32

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impl<'r> Decode<'r, Sqlite> for u8

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impl<'r, T1, T2, T3, T4, T5> Decode<'r, Postgres> for (T1, T2, T3, T4, T5)where T1: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T2: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T3: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T4: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T5: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>,

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, Postgres> for BigDecimal

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl Decode<'_, Postgres> for i64

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl Decode<'_, MySql> for u32

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impl<'r> Decode<'r, Mssql> for Cow<'r, str>

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impl<'r> Decode<'r, Sqlite> for Vec<u8>

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impl Decode<'_, Postgres> for i16

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for DateTime<FixedOffset>

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impl<'r> Decode<'r, MySql> for NaiveDate

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impl<'r> Decode<'r, Postgres> for ()

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fn decode(_value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, Mssql> for i16

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impl<'r> Decode<'r, Postgres> for DateTime<FixedOffset>

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<const N: usize> Decode<'_, Postgres> for [u8; N]

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl Decode<'_, Postgres> for IpNetwork

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl<'r, T1, T2> Decode<'r, Postgres> for (T1, T2)where T1: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T2: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>,

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, Postgres> for i32

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for NaiveDateTime

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impl<'r> Decode<'r, MySql> for DateTime<Utc>

Note: assumes the connection’s time_zone is set to +00:00 (UTC).

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impl Decode<'_, Postgres> for f64

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Any> for NaiveTimewhere NaiveTime: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for u16

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impl<'r> Decode<'r, Mssql> for &'r [u8]

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impl<'r> Decode<'r, Postgres> for Date

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Postgres> for PrimitiveDateTime

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for Date

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impl<'r> Decode<'r, Postgres> for Time

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, MySql> for Decimal

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impl Decode<'_, Postgres> for f32

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, MySql> for &'r str

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impl<'r> Decode<'r, Any> for i16where i16: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, MySql> for u16

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impl<'r> Decode<'r, MySql> for NaiveTime

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impl<'r> Decode<'r, Postgres> for DateTime<Utc>

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, Mssql> for DateTime<FixedOffset>

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impl<'r> Decode<'r, Postgres> for NaiveTime

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, Postgres> for i8

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Any> for i32where i32: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Postgres> for &'r [u8]

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, MySql> for i64

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impl<'r> Decode<'r, Postgres> for &'r str

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for &'r str

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impl<'r> Decode<'r, MySql> for Time

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impl<'r> Decode<'r, MySql> for NaiveDateTime

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impl<'r, T1, T2, T3, T4, T5, T6> Decode<'r, Postgres> for (T1, T2, T3, T4, T5, T6)where T1: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T2: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T3: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T4: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T5: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T6: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>,

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Mssql> for Cow<'r, [u8]>

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impl Decode<'_, Sqlite> for Hyphenated

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impl Decode<'_, MySql> for u8

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impl Decode<'_, Postgres> for String

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl Decode<'_, Mssql> for f32

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impl<'r, T1, T2, T3, T4> Decode<'r, Postgres> for (T1, T2, T3, T4)where T1: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T2: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T3: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T4: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>,

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Any> for Vec<u8>where Vec<u8>: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for Cow<'r, str>

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impl<'r> Decode<'r, Sqlite> for f32

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impl Decode<'_, Postgres> for Uuid

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl Decode<'_, Mssql> for f64

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impl<'r> Decode<'r, Any> for boolwhere bool: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for PrimitiveDateTime

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impl<'r> Decode<'r, Sqlite> for DateTime<Local>

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impl Decode<'_, MySql> for f32

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impl<'r> Decode<'r, Sqlite> for OffsetDateTime

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impl<'r> Decode<'r, Any> for f32where f32: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, Mssql> for i64

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impl<'r> Decode<'r, Sqlite> for NaiveDate

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impl Decode<'_, MySql> for Hyphenated

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impl<'r> Decode<'r, Sqlite> for Time

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impl Decode<'_, MySql> for Vec<u8>

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impl Decode<'_, Mssql> for bool

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impl<'r> Decode<'r, Sqlite> for i64

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impl<'r> Decode<'r, MySql> for PrimitiveDateTime

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impl<'r, T1, T2, T3, T4, T5, T6, T7> Decode<'r, Postgres> for (T1, T2, T3, T4, T5, T6, T7)where T1: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T2: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T3: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T4: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T5: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T6: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>, T7: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>,

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, MySql> for DateTime<Local>

Note: assumes the connection’s time_zone is set to +00:00 (UTC).

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impl Decode<'_, MySql> for i16

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impl<'r> Decode<'r, Any> for f64where f64: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Postgres> for NaiveDateTime

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Postgres> for OffsetDateTime

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, Mssql> for NaiveTime

Decodes Time values received from the server

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impl Decode<'_, Postgres> for MacAddress

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, MySql> for Date

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impl<'r> Decode<'r, MySql> for &'r [u8]

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impl<'r> Decode<'r, Any> for &'r strwhere &'r str: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Any> for Stringwhere String: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, MySql> for BigDecimal

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impl<'r> Decode<'r, Any> for NaiveDateTimewhere NaiveDateTime: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Sqlite> for f64

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impl<'r> Decode<'r, Sqlite> for String

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impl Decode<'_, Mssql> for i32

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impl Decode<'_, Sqlite> for Uuid

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impl<'r> Decode<'r, Any> for NaiveDatewhere NaiveDate: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, MySql> for Cow<'r, str>

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impl Decode<'_, Mssql> for u8

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impl Decode<'_, Postgres> for Vec<u8>

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

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impl Decode<'_, MySql> for i32

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impl Decode<'_, MySql> for String

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impl<'r, T1> Decode<'r, Postgres> for (T1,)where T1: 'r + Type<Postgres> + for<'a> Decode<'a, Postgres>,

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fn decode(value: PgValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, MySql> for bool

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impl<'r> Decode<'r, Any> for i64where i64: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl<'r, DB, T> Decode<'r, DB> for Option<T>where DB: Database, T: Decode<'r, DB>,

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fn decode(value: <DB as HasValueRef<'r>>::ValueRef) -> Result<Self, BoxDynError>

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impl<'db> Decode<'db, Postgres> for IpAddrwhere IpNetwork: Decode<'db, Postgres>,

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fn decode(value: PgValueRef<'db>) -> Result<Self, BoxDynError>

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impl<'r> Decode<'r, Any> for DateTime<Utc>where DateTime<Utc>: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> Result<Self, BoxDynError>

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impl Decode<'_, Postgres> for bool

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fn decode(value: PgValueRef<'_>) -> Result<Self, BoxDynError>

Implementors§

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impl Decode<'_, Postgres> for Oid

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impl Decode<'_, Postgres> for PgMoney

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impl<'de> Decode<'de, Postgres> for PgInterval

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impl<'r> Decode<'r, Postgres> for PgLQuery

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impl<'r> Decode<'r, Postgres> for PgLTree

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impl<'r> Decode<'r, Postgres> for PgTimeTz<NaiveTime, FixedOffset>

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impl<'r> Decode<'r, Postgres> for PgTimeTz<Time, UtcOffset>

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impl<'r, DB> Decode<'r, DB> for &'r JsonRawValuewhere Json<Self>: Decode<'r, DB>, DB: Database,

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impl<'r, DB> Decode<'r, DB> for JsonValuewhere Json<Self>: Decode<'r, DB>, DB: Database,

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impl<'r, T> Decode<'r, MySql> for Json<T>where T: 'r + Deserialize<'r>,

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impl<'r, T> Decode<'r, Postgres> for PgRange<T>where T: Type<Postgres> + for<'a> Decode<'a, Postgres>,

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impl<'r, T> Decode<'r, Postgres> for Json<T>where T: Deserialize<'r> + 'r,

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impl<'r, T> Decode<'r, Sqlite> for Json<T>where T: 'r + Deserialize<'r>,