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 NaiveDateTimewhere NaiveDateTime: 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<'_, Mssql> for u8

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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 Decode<'_, MySql> for f64

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impl Decode<'_, MySql> for Uuid

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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 Decode<'_, Mssql> for i16

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impl Decode<'_, Mssql> for Decimal

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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 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 &'r str

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impl Decode<'_, Mssql> for f32

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impl Decode<'_, Sqlite> for Uuid

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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 NaiveDateTime

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

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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 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, 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, Postgres> for Date

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fn decode(value: PgValueRef<'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<'_, Mssql> for Vec<u8>

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

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impl Decode<'_, MySql> for bool

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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<'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 Decode<'_, Mssql> for String

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

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impl Decode<'_, MySql> for u32

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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, MySql> for DateTime<Utc>

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

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impl Decode<'_, MySql> for u64

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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 Decode<'_, MySql> for i16

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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, 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 &'r str

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

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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, 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, MySql> for NaiveTime

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

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

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

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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, MySql> for OffsetDateTime

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

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

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impl Decode<'_, Mssql> for f64

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

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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<'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 IpNetwork

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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, Sqlite> for DateTime<Local>

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

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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, 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<'_, MySql> for i64

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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 Decode<'_, MySql> for u16

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

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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 Decode<'_, MySql> for Hyphenated

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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, 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 i32

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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 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, Sqlite> for OffsetDateTime

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

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

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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<'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 OffsetDateTime

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

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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<'_, MySql> for f32

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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 i8

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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 Stringwhere String: AnyDecode<'r>,

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

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

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

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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, Postgres> for &'r str

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

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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 Decode<'_, Mssql> for bool

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

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

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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<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 MacAddress

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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 Decode<'_, Mssql> for BigDecimal

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impl Decode<'_, MySql> for String

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

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

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impl Decode<'_, MySql> for Decimal

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impl Decode<'_, Mssql> for NaiveDateTime

Decodes DateTime2N values received from the server

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

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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 Decode<'_, MySql> for BigDecimal

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impl Decode<'_, Mssql> for NaiveTime

Decodes Time values received from the server

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

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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, 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 Cow<'r, str>

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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, Sqlite> for f32

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

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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, 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<'_, Postgres> for BitVec

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

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

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

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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 PrimitiveDateTime

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

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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 Date

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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 NaiveDatewhere NaiveDate: AnyDecode<'r>,

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fn decode(value: AnyValueRef<'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, Sqlite> for NaiveDate

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

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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 DateTime<Utc>

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impl Decode<'_, Sqlite> for Hyphenated

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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<'_, Mssql> for i32

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, 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>,