Rust-Postgres ============= A native PostgreSQL driver for Rust. Documentation is available at http://www.rust-ci.org/sfackler/rust-postgres/doc/postgres/. [![Build Status](https://travis-ci.org/sfackler/rust-postgres.png?branch=master)](https://travis-ci.org/sfackler/rust-postgres) Overview ======== Rust-Postgres is a pure-Rust frontend for the popular PostgreSQL database. It exposes a high level interface in the vein of JDBC or Go's `database/sql` package. ```rust extern crate postgres; extern crate extra; use extra::time; use extra::time::Timespec; use postgres::{PostgresConnection, PostgresStatement, NoSsl}; use postgres::types::ToSql; struct Person { id: i32, name: ~str, time_created: Timespec, data: Option<~[u8]> } fn main() { let conn = PostgresConnection::connect("postgres://postgres@localhost", &NoSsl); conn.execute("CREATE TABLE person ( id SERIAL PRIMARY KEY, name VARCHAR NOT NULL, time_created TIMESTAMP NOT NULL, data BYTEA )", []); let me = Person { id: 0, name: ~"Steven", time_created: time::get_time(), data: None }; conn.execute("INSERT INTO person (name, time_created, data) VALUES ($1, $2, $3)", [&me.name as &ToSql, &me.time_created as &ToSql, &me.data as &ToSql]); let stmt = conn.prepare("SELECT id, name, time_created, data FROM person"); for row in stmt.query([]) { let person = Person { id: row[1], name: row[2], time_created: row[3], data: row[4] }; println!("Found person {}", person.name); } } ``` Requirements ============ * **Rust** - Rust-Postgres is developed against the *master* branch of the Rust repository. It will most likely not build against the releases on http://www.rust-lang.org. * **PostgreSQL 7.4 or later** - Rust-Postgres speaks version 3 of the PostgreSQL protocol, which corresponds to versions 7.4 and later. If your version of Postgres was compiled in the last decade, you should be okay. Usage ===== Connecting ---------- Connect to a Postgres server using the standard URI format: ```rust let conn = PostgresConnection::connect("postgres://user:pass@host:port/database?arg1=val1&arg2=val2", &NoSsl); ``` `pass` may be omitted if not needed. `port` defaults to `5432` and `database` defaults to the value of `user` if not specified. The driver supports `trust`, `password`, and `md5` authentication. Statement Preparation --------------------- Prepared statements can have parameters, represented as `$n` where `n` is an index into the parameter array starting from 1: ```rust let stmt = conn.prepare("SELECT * FROM foo WHERE bar = $1 AND baz = $2"); ``` Querying -------- A prepared statement can be executed with the `query` and `execute` methods. Both methods take an array of parameters to bind to the query represented as `&ToSql` trait objects. `execute` returns the number of rows affected by the query (or 0 if not applicable): ```rust let stmt = conn.prepare("UPDATE foo SET bar = $1 WHERE baz = $2"); let updates = stmt.execute([&1i32 as &ToSql, & &"biz" as &ToSql]); println!("{} rows were updated", updates); ``` `query` returns an iterator over the rows returned from the database. The fields in a row can be accessed either by their indices or their column names, though access by index is more efficient. Like statement parameters, result columns are one-indexed. ```rust let stmt = conn.prepare("SELECT bar, baz FROM foo"); for row in stmt.query([]) { let bar: i32 = row[1]; let baz: ~str = row["baz"]; println!("bar: {}, baz: {}", bar, baz); } ``` In addition, `PostgresConnection` has a utility `execute` method which is useful if a statement is only going to be executed once: ```rust let updates = conn.execute("UPDATE foo SET bar = $1 WHERE baz = $2", [&1i32 as &ToSql, & &"biz" as &ToSql]); println!("{} rows were updated", updates); ``` Transactions ------------ The `transaction` method will start a new transaction. It returns a `PostgresTransaction` object which has the functionality of a `PostgresConnection` as well as methods to control the result of the transaction: ```rust let trans = conn.transaction(); trans.execute(...); let stmt = trans.prepare(...); if a_bad_thing_happened { trans.set_rollback(); } if the_coast_is_clear { trans.set_commit(); } drop(trans); ``` The transaction will be active until the `PostgresTransaction` object falls out of scope. A transaction will commit by default. Nested transactions are supported via savepoints. Error Handling -------------- The methods described above will fail if there is an error. For each of these methods, there is a second variant prefixed with `try_` which returns a `Result`: ```rust match conn.try_execute(query, params) { Ok(updates) => println!("{} rows were updated", updates), Err(err) => match err.code { PgDbError(NotNullViolation) => println!("Something was NULL that shouldn't be"), PgDbError(SyntaxError) => println!("Invalid query syntax"), _ => println!("A bad thing happened: {}", err), } } ``` Connection Pooling ------------------ A very basic fixed-size connection pool is provided in the `pool` module. A single pool can be shared across tasks and `get_connection` will block until a connection is available. ```rust let pool = PostgresConnectionPool::new("postgres://postgres@localhost", NoSsl, 5); for _ in range(0, 10) { let pool = pool.clone(); spawn(proc() { let conn = pool.get_connection(); conn.query(...); }) } ``` Type Correspondence ------------------- Rust-Postgres enforces a strict correspondence between Rust types and Postgres types. The driver currently supports the following conversions:
Rust Type Postgres Type
bool BOOL
i8 "char"
i16 SMALLINT, SMALLSERIAL
i32 INT, SERIAL
i64 BIGINT, BIGSERIAL
f32 REAL
f64 DOUBLE PRECISION
str VARCHAR, CHAR(n), TEXT
[u8] BYTEA
extra::json::Json JSON
extra::uuid::Uuid UUID
extra::time::Timespec TIMESTAMP, TIMESTAMP WITH TIME ZONE
types::range::Range<i32> INT4RANGE
types::range::Range<i64> INT8RANGE
types::range::Range<Timespec> TSRANGE, TSTZRANGE
types::array::ArrayBase<Option<bool>> BOOL[], BOOL[][], ...
types::array::ArrayBase<Option<~[u8]>> BYTEA[], BYTEA[][], ...
types::array::ArrayBase<Option<i8>> "char"[], "char"[][], ...
types::array::ArrayBase<Option<i16>> INT2[], INT2[][], ...
types::array::ArrayBase<Option<i32>> INT4[], INT4[][], ...
types::array::ArrayBase<Option<~str>> TEXT[], CHAR(n)[], VARCHAR[], TEXT[][], ...
types::array::ArrayBase<Option<Json>> JSON[], JSON[][], ...
types::array::ArrayBase<Option<i64>> INT8[], INT8[][], ...
types::array::ArrayBase<Option<Timespec>> TIMESTAMP[], TIMESTAMPTZ[], TIMESTAMP[][], ...
types::array::ArrayBase<Option<f32>> FLOAT4[], FLOAT4[][], ...
types::array::ArrayBase<Option<f64>> FLOAT8[], FLOAT8[][], ...
types::array::ArrayBase<Option<Uuid>> UUID[], UUID[][], ...
types::array::ArrayBase<Option<Range<i32>>> INT4RANGE[], INT4RANGE[][], ...
types::array::ArrayBase<Option<Range<Timespec>>> TSRANGE[], TSTZRANGE[], TSRANGE[][], ...
types::array::ArrayBase<Option<Range<i64>>> INT8RANGE[], INT8RANGE[][], ...
std::hashmap::HashMap<~str, Option<~str>> HSTORE
More conversions can be defined by implementing the `ToSql` and `FromSql` traits. Development =========== Like Rust itself, Rust-Postgres is still in the early stages of development, so don't be surprised if APIs change and things break. If something's not working properly, file an issue or submit a pull request!