#jaredzhou/moonpg

#Overview

• Connection — connect, authenticate (cleartext / MD5 / SCRAM-SHA-256), query, close.
• Pool — bounded connection pool with acquire / release, min-idle, and idle-timeout expiry.
• Transactions — begin_tx / commit / rollback on bare connections and pooled connections, plus begin_func (auto-commit/rollback).
• Rows trait — polymorphic row iteration (ConnRows, PoolRows); pull-based with has_next() / get_row().
• Typed decoding — FromRaw trait for Int, Int64, Double, Bool, String, Bytes, Json, Decimal, UUID, Timestamp, plus Option[T] for nullable columns.
• Parameterised queries — $1-style placeholders via the extended query protocol; ToValue trait with impls for all basic types and Option[T].
• Async concurrency — multiple connections can run queries concurrently; a slow query on one connection never blocks others.

#Install

moon add jaredzhou/moonpg

#Quick start

let conn = @moonpg.connect("postgres://user:pw@localhost:5432/db")

// Simple query
let rows = conn.query("SELECT id, name FROM users")
while rows.has_next() {
  let row = rows.get_row()
  let id : Int = row.get(0)
  let name : String = row.get_by_name("name")
  println("\{id}: \{name}")
}
rows.close()

// Parameterised — extended query protocol
conn.execute(
  "UPDATE users SET email = $1 WHERE id = $2",
  params=[None, 42],  // Option[T] encodes NULL
) |> ignore

conn.close()

#Connection pool

let pool = Pool::new(PoolConfig::new(
  "postgres://user:pw@localhost:5432/db",
  max_conns=10,
  min_idle=2,
))

// Implicit acquire — rows.close() returns conn to pool
let rows = pool.query("SELECT 1")
while rows.has_next() {
  let row = rows.get_row()
  // ...
}
rows.close()

let row = pool.query_one("SELECT 42")
pool.execute("INSERT INTO t (x) VALUES ($1)", params=[1]) |> ignore

// Explicit acquire — caller controls release
let pc = pool.acquire()
let r = pc.execute("INSERT INTO t (x) VALUES ($1)", params=[99])
r.close()
pc.release()

#Transactions

// Auto-commit / rollback

///|
let result = begin_func(conn, async fn(tx) {
  tx.execute("INSERT INTO users (name) VALUES ($1)", params=["alice"]) |> ignore
  tx.query_one("SELECT id FROM users WHERE name = $1", params=["alice"]).get(0)
}) // exception → rollback; success → commit

#Typed decoding

///|
let id : Int = row.get(0) // raises on NULL

///|
let email : String? = row.get_by_name("email") // NULL → None

///|
let ts : Timestamp = row.get(2) // pg timestamp → Unix µs

#Architecture

#Run the tests

# Use env var or defaults (see conn_test.mbt)
MOONPG_CONNINFO="postgres://moonpg_plain:plain_pass@localhost:5432/moonpg_test" \
  moon test --target native

#License