Diesel PGRX

Integration layer enabling Diesel ORM to work with custom Rust types defined in PGRX PostgreSQL extensions. The crate provides a derive macro that implements Diesel's serialization traits (ToSql and FromSql) using PGRX's binary protocol, which internally uses CBOR serialization via serde_cbor. This allows types decorated with PGRX's PostgresType and #[pg_binary_protocol] to be seamlessly queried through Diesel. Additional backend support includes SQLite using the same CBOR serialization format.

Usage

Add this to your Cargo.toml:

[dependencies]
diesel_pgrx = "0.1"
diesel = { version = "2.2", features = ["postgres"] }
serde = { version = "1.0", features = ["derive"] }

After building your PGRX extension, install it in PostgreSQL:

CREATE EXTENSION your_extension;

Derive DieselPGRX for types that implement serde::Serialize and serde::Deserialize. The type must also use PGRX's PostgresType and pg_binary_protocol attributes:

#[derive(
    Debug,
    serde::Serialize,
    serde::Deserialize,
    diesel_pgrx::DieselPGRX,
    diesel::FromSqlRow,
    diesel::AsExpression
)]
#[cfg_attr(feature = "pgrx", derive(pgrx::PostgresType))]
#[cfg_attr(feature = "pgrx", pg_binary_protocol)]
#[diesel(sql_type = diesel_impls::MyCustomType)]
pub struct MyCustomType {
    pub field: i32,
}

Additional PGRX Derives

PGRX provides optional derives for comparison and hashing operations. When using these, implement the corresponding Rust traits:

#[derive(serde::Serialize, serde::Deserialize, diesel_pgrx::DieselPGRX)]
#[cfg_attr(
    feature = "pgrx",
    derive(pgrx::PostgresType, pgrx::PostgresEq, pgrx::PostgresOrd, pgrx::PostgresHash)
)]
#[cfg_attr(feature = "pgrx", pg_binary_protocol)]
#[derive(
    Debug,
    Copy,
    Clone,
    PartialEq,
    Eq,
    PartialOrd,
    Ord,
    Hash,
    diesel::FromSqlRow,
    diesel::AsExpression,
)]
#[diesel(sql_type = diesel_impls::MyCustomType)]
pub struct MyCustomType {
    pub field: i32,
}

Feature Flags

• postgres (not default): Enables PostgreSQL backend support with binary protocol serialization
• sqlite (not default): Enables SQLite backend support using CBOR-encoded BINARY type
• pgrx: Used for documentation tests only

Note on serde_cbor

The serde_cbor crate is archived but remains the CBOR implementation used by PGRX. No known issues exist, and it will be used until PGRX adopts an alternative.