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<'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<'_, MySql> for bool

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

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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<'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 PrimitiveDateTime

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

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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 NaiveTime

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

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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 i64

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

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

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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 Decode<'_, MySql> for u32

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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<'_, Postgres> for Vec<u8>

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

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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<'_, MySql> for Uuid

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

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

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

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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 Date

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

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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<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<'_, Sqlite> for Hyphenated

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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, MySql> for &'r [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<'r> Decode<'r, MySql> for Time

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

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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, Postgres> for Date

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

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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, Sqlite> for u16

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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<'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, Sqlite> for String

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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<'_, Postgres> for IpNetwork

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

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

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impl Decode<'_, MySql> for i32

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

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impl Decode<'_, MySql> for Decimal

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impl Decode<'_, MySql> for u16

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impl Decode<'_, MySql> for String

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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 i8

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

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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, Sqlite> for i32

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

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

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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<'_, Postgres> for bool

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

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

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

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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, 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 OffsetDateTime

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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, Sqlite> for DateTime<Local>

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

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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 &'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 NaiveDateTime

Decodes DateTime2N values received from the server

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impl Decode<'_, MySql> for Hyphenated

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

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impl Decode<'_, MySql> for f64

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impl Decode<'_, Mssql> for i8

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impl Decode<'_, Mssql> for NaiveTime

Decodes Time values received from the server

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

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

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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, 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, Sqlite> for f64

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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, 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 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<'_, MySql> for f32

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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 DateTime<Utc>

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

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impl Decode<'_, Mssql> for f32

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impl Decode<'_, MySql> for BigDecimal

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impl Decode<'_, Sqlite> for Uuid

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impl Decode<'_, MySql> for i8

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

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impl Decode<'_, Mssql> for u8

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impl Decode<'_, MySql> for i16

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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<'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 i16

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

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

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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 Decode<'_, Postgres> for Uuid

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fn decode(value: PgValueRef<'_>) -> 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, 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, Any> for i64where i64: AnyDecode<'r>,

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

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impl Decode<'_, MySql> for u8

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impl Decode<'_, MySql> for u64

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

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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, MySql> for NaiveDate

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impl Decode<'_, Mssql> for f64

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

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

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impl Decode<'_, Mssql> for bool

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

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impl Decode<'_, Mssql> for i32

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

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

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fn decode(value: PgValueRef<'r>) -> 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 Decode<'_, Mssql> for i64

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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, MySql> for NaiveTime

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

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

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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, 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>,