Crate postgres_types
source ·Expand description
Conversions to and from Postgres types.
This crate is used by the tokio-postgres
and postgres
crates. You normally don’t need to depend directly on it
unless you want to define your own ToSql
or FromSql
definitions.
Derive
If the derive
cargo feature is enabled, you can derive ToSql
and FromSql
implementations for custom Postgres
types. Explicitly, modify your Cargo.toml
file to include the following:
[dependencies]
postgres-types = { version = "0.X.X", features = ["derive"] }
Enums
Postgres enums correspond to C-like enums in Rust:
CREATE TYPE "Mood" AS ENUM (
'Sad',
'Ok',
'Happy'
);
use postgres_types::{ToSql, FromSql};
#[derive(Debug, ToSql, FromSql)]
enum Mood {
Sad,
Ok,
Happy,
}
Domains
Postgres domains correspond to tuple structs with one member in Rust:
CREATE DOMAIN "SessionId" AS BYTEA CHECK(octet_length(VALUE) = 16);
use postgres_types::{ToSql, FromSql};
#[derive(Debug, ToSql, FromSql)]
struct SessionId(Vec<u8>);
Newtypes
The #[postgres(transparent)]
attribute can be used on a single-field tuple struct to create a
Rust-only wrapper type that will use the ToSql
& FromSql
implementation of the inner
value :
use postgres_types::{ToSql, FromSql};
#[derive(Debug, ToSql, FromSql)]
#[postgres(transparent)]
struct UserId(i32);
Composites
Postgres composite types correspond to structs in Rust:
CREATE TYPE "InventoryItem" AS (
name TEXT,
supplier_id INT,
price DOUBLE PRECISION
);
use postgres_types::{ToSql, FromSql};
#[derive(Debug, ToSql, FromSql)]
struct InventoryItem {
name: String,
supplier_id: i32,
price: Option<f64>,
}
Naming
The derived implementations will enforce exact matches of type, field, and variant names between the Rust and
Postgres types. The #[postgres(name = "...")]
attribute can be used to adjust the name on a type, variant, or
field:
CREATE TYPE mood AS ENUM (
'sad',
'ok',
'happy'
);
use postgres_types::{ToSql, FromSql};
#[derive(Debug, ToSql, FromSql)]
#[postgres(name = "mood")]
enum Mood {
#[postgres(name = "sad")]
Sad,
#[postgres(name = "ok")]
Ok,
#[postgres(name = "happy")]
Happy,
}
Macros
ToSql::accepts
which accepts the
types passed to it.ToSql::to_sql_checked
.Structs
Serialize
/Deserialize
types to convert to Postgres JSON values.PG_LSN
type.NULL
Postgres value was passed to a FromSql
implementation that does not support NULL
values.Enums
Type::Date
types.Type::Timestamp
and Type::Timestamptz
types.Traits
&dyn ToSql
and T: ToSql
.