[−][src]Crate postgres_mapper
postgres-mapper
postgres-mapper
is a proc-macro designed to make mapping from postgresql
tables to structs simple.
Why?
It can be frustrating to write a lot of boilerplate and, ultimately, duplicated code for mapping from postgres Rows into structs.
For example, this might be what someone would normally write:
extern crate postgres; use postgres::rows::Row; pub struct User { pub id: i64, pub name: String, pub email: Option<String>, } impl From<Row> for User { fn from(row: Row) -> Self { Self { id: row.get("id"), name: row.get("name"), email: row.get("email"), } } } // code to execute a query here and get back a row let user = User::from(row); // this can panic
This becomes worse when manually implementating using the non-panicking
get_opt
method variant.
Using this crate, the boilerplate is removed, and panicking and non-panicking implementations are derived:
#[macro_use] extern crate postgres_mapper_derive; extern crate postgres_mapper; use postgres_mapper::FromPostgresRow; #[derive(PostgresMapper)] pub struct User { pub id: i64, pub name: String, pub email: Option<String>, } // code to execute a query here and get back a row // `postgres_mapper::FromPostgresRow`'s methods do not panic and return a Result let user = User::from_postgres_row(row)?;
The two crates
This repository contains two crates: postgres-mapper
which contains an Error
enum and traits for converting from a postgres
or tokio-postgres
Row
without panicking, and postgres-mapper-derive
which contains the proc-macro.
postgres-mapper-derive
has 3 features that can be enabled (where T is the
struct being derived with the provided PostgresMapper
proc-macro):
postgres-support
, which derivesimpl<'a> From<::postgres::rows::Row<'a>> for T
andimpl<'a> From<&'a ::postgres::Row<'a>> for T
implementationstokio-postgres-support
, which derivesimpl From<::tokio_postgres::rows::Row> for T
andimpl From<&::tokio_postgres::rows::Row> for T
implementationspostgres-mapper
which, for each of the above features, implementspostgres-mapper
'sFromPostgresRow
and/orFromTokioPostgresRow
traits
postgres-mapper
has two features, postgres-support
and
tokio-postgres-support
. When one is enabled in postgres-mapper-derive
, it
must also be enabled in postgres-mapper
.
Installation
The above might be confusing, so here's an example where tokio-postgres
is
enabled in both crates:
Add the following to your Cargo.toml
:
[dependencies.postgres-mapper]
features = ["tokio-postgres-support"]
version = "0.1"
[dependencies.postgres-mapper-derive]
features = ["postgres-mapper", "tokio-postgres-support"]
version = "0.1"
This will derive implementations for converting from owned and referenced
tokio-postgres::rows::Row
s, as well as implementing postgres-mapper
's
FromTokioPostgresRow
trait for non-panicking conversions.
Enums
Error | General error type returned throughout the library. |
Traits
FromPostgresRow | Trait containing various methods for converting from a postgres Row to a mapped type. |