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 NaiveDate

Decodes Date values received from the server

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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 i16

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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, Postgres> for Time

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

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

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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<'_, MySql> for BigDecimal

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

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

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

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

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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, 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<'_, Postgres> for String

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

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impl Decode<'_, Sqlite> for Hyphenated

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

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

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impl Decode<'_, MySql> for Decimal

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impl Decode<'_, Mssql> for i8

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impl Decode<'_, Postgres> for bool

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

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impl Decode<'_, Mssql> for bool

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impl Decode<'_, Mssql> for BigDecimal

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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<'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 Decode<'_, Mssql> for i32

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

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

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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<'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 Decode<'_, Postgres> for BitVec

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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, Any> for BigDecimalwhere BigDecimal: AnyDecode<'r>,

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

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

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impl Decode<'_, MySql> for f64

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impl Decode<'_, Mssql> for NaiveTime

Decodes Time values received from the server

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impl Decode<'_, Sqlite> for BigDecimal

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impl Decode<'_, MySql> for bool

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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 Decode<'_, MySql> for i64

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

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impl Decode<'_, MySql> for i8

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

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

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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<'_, MySql> for Vec<u8>

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impl Decode<'_, MySql> for u16

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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 Decode<'_, Sqlite> for Uuid

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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 Decode<'_, Postgres> for i64

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

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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, 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, 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, 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 Stringwhere String: AnyDecode<'r>,

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

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

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

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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> Decode<'r, Sqlite> for u32

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

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fn decode(value: PgValueRef<'_>) -> 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 Decode<'_, Mssql> for String

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

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

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

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impl Decode<'_, Sqlite> for Decimal

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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 Decode<'_, Mssql> for NaiveDateTime

Decodes DateTime2N values received from the server

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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 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 boolwhere bool: AnyDecode<'r>,

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

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impl Decode<'_, Mssql> for u8

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

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

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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, 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 Decode<'_, Mssql> for f32

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

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impl Decode<'_, MySql> for Hyphenated

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impl Decode<'_, MySql> for u64

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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 NaiveDate

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impl Decode<'_, Mssql> for i64

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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<'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 Decode<'_, Mssql> for f64

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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, 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, MySql> for NaiveTime

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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 Decode<'_, Postgres> for i32

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

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

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

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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 Decode<'_, MySql> for String

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impl Decode<'_, MySql> for f32

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

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

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

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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<'_, Mssql> for Decimal

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

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

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impl Decode<'_, MySql> for Uuid

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impl Decode<'_, MySql> for u8

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

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fn decode(value: AnyValueRef<'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, Any> for Decimalwhere Decimal: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'r>) -> 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<'_, MySql> for u32

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

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

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

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

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

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

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impl Decode<'_, MySql> for i32

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

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

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

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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, Mssql> for &'r [u8]

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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> Decode<'r, Sqlite> for f32

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impl Decode<'_, MySql> for i16

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

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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<'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>

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, Any> for Valuewhere Value: AnyDecode<'r>,

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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, Mssql> for Json<T>where T: Deserialize<'r> + 'r,

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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>,