generated from tpl/purs
318 lines
14 KiB
Markdown
318 lines
14 KiB
Markdown
# postgresql
|
|
|
|
Purescript PostgreSQL driver
|
|
|
|
## Table of Contents
|
|
- [Getting Started](#getting-started)
|
|
- [Data](#data)
|
|
- [Rows](#data---rows)
|
|
- [Ranges](#data---ranges)
|
|
- [Queries](#queries)
|
|
- [Builder](#queries---builder)
|
|
- [Monads](#monads)
|
|
- [`PostgresT`](#monads---postgrest)
|
|
- [`SessionT`](#monads---sessiont)
|
|
- [`CursorT`](#monads---cursort)
|
|
- [`node-postgres` style](#node-postgres-style)
|
|
|
|
## Getting Started
|
|
Install with:
|
|
```bash
|
|
> spago install postgresql
|
|
# (npm | yarn | bun) install pg
|
|
```
|
|
|
|
Next, create a pool [`Config`] object:
|
|
|
|
```purescript
|
|
-- from a connection string:
|
|
pgConfig =
|
|
{ connectionString: "postgresql://postgres:password@localhost:5432/postgres"
|
|
}
|
|
|
|
-- or explicitly:
|
|
pgConfig =
|
|
{ username: "postgres"
|
|
, password: "password"
|
|
, host: "localhost"
|
|
, port: 5432
|
|
, database: "postgres"
|
|
}
|
|
```
|
|
|
|
Then in an `Aff`, use `runPostgres` to connect to the database and execute
|
|
queries:
|
|
```purescript
|
|
module Main where
|
|
|
|
import Prelude
|
|
import Effect (Effect)
|
|
import Effect.Class (liftEffect)
|
|
import Effect.Aff (launchAff_)
|
|
import Effect.Console (log)
|
|
import Control.Monad.Postgres (runPostgres, query)
|
|
|
|
main :: Effect Unit
|
|
main =
|
|
launchAff_ do
|
|
msg <- runPostgres pgConfig $ query "select 'hello, world!'"
|
|
liftEffect $ log msg -- logs 'hello, world!'
|
|
```
|
|
|
|
[`runPostgres`] creates a connection pool, then executes a
|
|
[`PostgresT`](#monads-postgrest) monad, which is an `Aff` with access
|
|
to a connection pool.
|
|
|
|
```purescript
|
|
runPostgres :: forall a. <partial config> -> PostgresT Aff a -> Aff a
|
|
```
|
|
|
|
[`query`] accepts any `q` that can be turned [into a query][`AsQuery`]
|
|
(here just a `String`), and [unmarshals][`FromRows`] the result into a
|
|
destination type `r`.
|
|
|
|
`query` is from [`MonadSession`], which [`PostgresT`] implements:
|
|
```purescript
|
|
class MonadSession m where
|
|
query :: forall q r. AsQuery q => FromRows r => q -> m r
|
|
-- ...
|
|
```
|
|
|
|
## Data
|
|
Single SQL values are serialized to and deserialized from JS via [`pg-types`]
|
|
(with some [tweaks][`modifyPgTypes`]).
|
|
|
|
The conversion between [`Raw`] JS values and purescript values is done
|
|
with the [`Serialize`] and [`Deserialize`] typeclasses.
|
|
|
|
The [`Rep`] class indicates a type is [`Rep`]resentable as a SQL value.
|
|
[`Rep`] is automatically implemented for all types that are [`Serialize`]
|
|
and [`Deserialize`].
|
|
|
|
Implementations are provided for `Int`, `String`, `DateTime`, `Buffer`,
|
|
`BigInt`, `Boolean`, `Number`, `Array`, [`Range`]s, `Maybe`, [`Null`]
|
|
and `Unit`.
|
|
|
|
### Data - Rows
|
|
A single row (multiple SQL values) are deserialized using [`FromRow`],
|
|
which is implemented for:
|
|
- n-tuples of [`Rep`] types
|
|
- `Array a` where `a` is [`Rep`]
|
|
- A single [`Rep`] type
|
|
|
|
Examples:
|
|
```purescript
|
|
(fromRow [] :: Maybe Int) == Nothing
|
|
(fromRow [1] :: Maybe Int) == Just 1
|
|
(fromRow [1, 2] :: Maybe Int) == Just 1
|
|
(fromRow [] :: Int /\ Int) == Error
|
|
(fromRow [1, 2] :: Int /\ Int) == 1 /\ 2
|
|
(fromRow [] :: Array Int) == []
|
|
(fromRow [1, 2] :: Array Int) == [1, 2]
|
|
```
|
|
|
|
Multiple rows are deserialized using [`FromRows`],
|
|
which is implemented for:
|
|
- `Array a` where `a` is [`FromRow`]
|
|
- `Maybe a` where `a` is [`FromRow`] (equivalent to `Array.head <<< fromRows`)
|
|
- `a` where `a` is [`FromRow`] (throws if 0 rows yielded)
|
|
- `RowsAffected`
|
|
- Extracts the number of rows processed by the last command in the query (ex. `INSERT INTO foo (bar) VALUES ('a'), ('b')` -> `INSERT 2` -> `RowsAffected 2`)
|
|
|
|
### Data - Ranges
|
|
Postgres ranges are represented with [`Range`].
|
|
|
|
[`Range`]s can be created with:
|
|
- `mempty` - an unbounded range
|
|
- [`Range.lt`]` a` - `(,a)`
|
|
- [`Range.lte`]` a` - `(,a]`
|
|
- [`Range.gt`]` a` - `(a,)`
|
|
- [`Range.gte`]` a` - `[a,)`
|
|
|
|
and combined with `append`:
|
|
```purescript
|
|
mempty <> lt 100 -- (,100)
|
|
gte 10 <> lt 100 -- [10,100)
|
|
```
|
|
|
|
## Queries
|
|
Queries can be executed with any type that implements [`AsQuery`],
|
|
which converts it into a [`Query`]:
|
|
|
|
```purescript
|
|
newtype Query = Query { text :: String, values :: Array Raw, name :: Maybe String }
|
|
|
|
class AsQuery a where
|
|
asQuery :: a -> Effect Query
|
|
```
|
|
|
|
[`AsQuery`] is implemented for:
|
|
- [`Query`]
|
|
- `String`
|
|
- `String /\ n` where `n` is:
|
|
- n-tuple of [`Rep`] query parameters
|
|
- a single [`Rep`] query parameter
|
|
- `Array `[`Raw`]
|
|
|
|
### Queries - Builder
|
|
For complex parameterized queries, there is a provided [`Query.Builder`]:
|
|
|
|
```purescript
|
|
runPostgres {} do
|
|
exec_ "create table person (id int, first_name text, last_name text, age int, born timestamptz);"
|
|
exec_
|
|
$ Query.Builder.build
|
|
$ do
|
|
id <- Query.Builder.param 1
|
|
firstName <- Query.Builder.param "Henry"
|
|
lastName <- Query.Builder.param "Cavill"
|
|
age <- Query.Builder.param 38
|
|
born <- Query.Builder.param "1985-05-05"
|
|
pure
|
|
$ intercalate "\n"
|
|
[ "insert into person (id, first_name, last_name, age, born)"
|
|
, "values"
|
|
, "("
|
|
, intercalate ", " [id, firstName, lastName, age, born])
|
|
, ")"
|
|
]
|
|
```
|
|
|
|
[`Query.Builder.param`] accepts any [`Rep`] value and returns a string (ex. `"$2"`)
|
|
that will reference that value in the query.
|
|
|
|
[`Query.Builder.build`] renders the query to [`Query`]
|
|
|
|
## Monads
|
|
### Monads - `PostgresT`
|
|
[`PostgresT`] is the database driver's main entry point,
|
|
and is just an `Aff` with access to a [`Pool`].
|
|
|
|
Run in `Aff` with [`runPostgres`]:
|
|
```purescript
|
|
main :: Effect Unit
|
|
main =
|
|
launchAff_ do
|
|
hi <- runPostgres {} $ query "select 'hi!'"
|
|
liftEffect $ log hi
|
|
```
|
|
|
|
Execute [`SessionT`] monads with [`session`] or [`transaction`]:
|
|
```purescript
|
|
dbMain :: PostgresT Aff Unit
|
|
dbMain = do
|
|
transaction do
|
|
exec_ """
|
|
create table persons
|
|
( id int primary key generated always as identity
|
|
, name text not null unique
|
|
);
|
|
"""
|
|
exec_ $ "insert into persons (name) values ($1);" /\ "Henry"
|
|
pure unit
|
|
```
|
|
|
|
Implements [`MonadSession`] as a shorthand for single-query [`session`]s:
|
|
```purescript
|
|
dbMain :: PostgresT Aff Int
|
|
dbMain = exec_ $ "insert into persons (name) values ($1);" /\ "Sarah"
|
|
-- equivalent to:
|
|
-- dbMain = session $ exec_ ...
|
|
```
|
|
|
|
Execute [`CursorT`] monads with [`cursor`]:
|
|
```purescript
|
|
dbMain :: PostgresT Aff Int
|
|
dbMain =
|
|
cursor @(Int /\ String) "people_cursor" "select id, name from persons" do
|
|
a <- fetchOne -- Just (1 /\ "Henry")
|
|
b <- fetchOne -- Just (2 /\ "Sarah")
|
|
void $ move (MoveRelative -2)
|
|
c <- fetchAll -- [1 /\ "Henry", 2 /\ "Sarah"]
|
|
d <- fetchOne -- Nothing
|
|
```
|
|
|
|
### Monads - `SessionT`
|
|
[`SessionT`] is an `Aff` with access to a [`Client`]
|
|
issued by a [`Pool`], connected to the database.
|
|
|
|
Run in [`PostgresT`] with [`session`] or [`transaction`]
|
|
|
|
Perform queries with [`query`], [`exec`] or [`exec_`]
|
|
|
|
### Monads - `CursorT`
|
|
[`CursorT`] is a transaction [`SessionT`] with access to a named server-side cursor.
|
|
|
|
Run in [`PostgresT`] with [`cursor`]
|
|
|
|
## `node-postgres` style
|
|
You may also choose to use the `Aff` API directly, which closely mirrors
|
|
the api of [`node-postgres`]:
|
|
|
|
- [`Client`]
|
|
- create with [`Client.make`] or [`Client.connected`]
|
|
- execute queries with [`Client.query`], [`Client.queryRaw`] or [`Client.exec`]
|
|
- release with [`Client.end`]
|
|
- [`Pool`]
|
|
- create with [`Pool.make`]
|
|
- issue clients with [`Pool.connect`]
|
|
- release clients with [`Pool.release`] or [`Pool.destroy`]
|
|
- release with [`Pool.end`]
|
|
|
|
[`Pool`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Pool#t:Pool
|
|
[`Config`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Pool#t:Config
|
|
[`Pool.make`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Pool#v:make
|
|
[`Pool.end`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Pool#v:end
|
|
[`Pool.connect`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Pool#v:connect
|
|
[`Pool.destroy`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Pool#v:destroy
|
|
[`Pool.release`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Pool#v:release
|
|
|
|
[`Client`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Client#t:Client
|
|
[`Client.end`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Client#v:end
|
|
[`Client.make`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Client#v:make
|
|
[`Client.connected`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Client#v:connected
|
|
[`Client.query`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Client#v:query
|
|
[`Client.queryRaw`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Client#v:queryRaw
|
|
[`Client.exec`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Effect.Aff.Postgres.Client#v:exec
|
|
|
|
[`Range`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Range#t:Range
|
|
[`Range.gt`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Range#v:gt
|
|
[`Range.gte`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Range#v:gte
|
|
[`Range.lt`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Range#v:lt
|
|
[`Range.lte`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Range#v:lte
|
|
|
|
[`Raw`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Raw#t:Raw
|
|
[`Null`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Raw#t:Null
|
|
|
|
[`Serialize`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres#t:Serialize
|
|
[`Deserialize`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres#t:Deserialize
|
|
[`Rep`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres#t:Rep
|
|
[`modifyPgTypes`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres#v:modifyPgTypes
|
|
|
|
[`Result`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Result#t:Result
|
|
[`FromRow`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Result#t:FromRow
|
|
[`FromRows`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Result#t:FromRows
|
|
|
|
[`Query`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Query#t:Query
|
|
[`AsQuery`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Query#t:AsQuery
|
|
|
|
[`Query.Builder`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Query.Builder#t:Builder
|
|
[`Query.Builder.param`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Query.Builder#v:param
|
|
[`Query.Builder.build`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Data.Postgres.Query.Builder#v:build
|
|
|
|
[`MonadCursor`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#t:MonadCursor
|
|
[`MonadSession`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#t:MonadSession
|
|
[`CursorT`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#t:CursorT
|
|
[`SessionT`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#t:SessionT
|
|
[`PostgresT`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#t:PostgresT
|
|
[`cursor`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#v:cursor
|
|
[`session`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#v:session
|
|
[`transaction`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#v:transaction
|
|
[`runPostgres`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#v:runPostgres
|
|
[`query`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#v:query
|
|
[`exec`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#v:exec
|
|
[`exec_`]: https://pursuit.purescript.org/////////////////////////////////////////packages/purescript-postgresql/1.7.1/Control.Monad.Postgres#v:exec_
|
|
|
|
[`node-postgres`]: https://node-postgres.com/
|
|
[`pg-types`]: https://github.com/brianc/node-pg-types/
|