persistant_sqlx/
lib.rs

1// SPDX-License-Identifier: MIT OR Apache-2.0
2//! PersistAnt's relational driver over sqlx (PostgreSQL first).
3//!
4//! [`PgBackend`] implements [`persistant_relational::RelationalBackend`]. The concrete
5//! [`sqlx::PgPool`] is available through [`PgBackend::pool`], so a program that wants
6//! compile-time-checked `sqlx::query!` keeps it (D1, C+): this crate does not hide sqlx.
7//!
8//! Failures are classified from the server's SQLSTATE into [`persistant_relational::RelError`].
9
10mod migrate;
11mod options;
12
13pub use migrate::{MigrateError, MigrateReport, Migration};
14pub use options::{ConnectOptions, TlsPolicy};
15
16use persistant_relational::{Dialect, RelError, RelationalBackend, RelationalTx, Row, Value};
17use sqlx::postgres::{PgArguments, PgPoolOptions, PgRow};
18use sqlx::query::Query;
19use sqlx::{Column, Postgres, Row as SqlxRow, TypeInfo, ValueRef};
20
21/// Classify an sqlx error by SQLSTATE (https://www.postgresql.org/docs/current/errcodes-appendix.html).
22pub(crate) fn classify(e: sqlx::Error) -> RelError {
23    match &e {
24        sqlx::Error::Database(db) => {
25            let constraint = db.constraint().map(str::to_string);
26            match db.code().as_deref() {
27                Some("23505") => RelError::UniqueViolation { constraint },
28                Some("23503") => RelError::ForeignKeyViolation { constraint },
29                Some("23514") | Some("23502") => RelError::CheckViolation { constraint },
30                Some("40001") => RelError::Serialization,
31                Some("40P01") => RelError::Deadlock,
32                Some(c) if c.starts_with("08") || c.starts_with("57P") => {
33                    RelError::Unavailable(e.to_string())
34                }
35                _ => RelError::Backend(e.to_string()),
36            }
37        }
38        sqlx::Error::Io(_) | sqlx::Error::PoolTimedOut | sqlx::Error::PoolClosed => {
39            RelError::Unavailable(e.to_string())
40        }
41        _ => RelError::Backend(e.to_string()),
42    }
43}
44
45fn bind<'q>(
46    mut q: Query<'q, Postgres, PgArguments>,
47    params: &'q [Value],
48) -> Result<Query<'q, Postgres, PgArguments>, RelError> {
49    for p in params {
50        q = match p {
51            // A typed NULL: PostgreSQL needs a type to infer parameter types; text works for the
52            // statements this layer issues. A caller needing another NULL type casts in SQL.
53            Value::Null => q.bind(Option::<String>::None),
54            Value::Bool(b) => q.bind(*b),
55            Value::Int(n) => q.bind(*n),
56            Value::Float(f) => q.bind(*f),
57            Value::Text(s) => q.bind(s.as_str()),
58            Value::Bytes(b) => q.bind(b.as_slice()),
59            other => {
60                return Err(RelError::Unsupported(format!(
61                    "parameter {other:?} has no PostgreSQL binding in this driver"
62                )));
63            }
64        };
65    }
66    Ok(q)
67}
68
69fn decode(row: &PgRow) -> Result<Row, RelError> {
70    let mut values = Vec::with_capacity(row.columns().len());
71    for (i, col) in row.columns().iter().enumerate() {
72        let raw = row.try_get_raw(i).map_err(classify)?;
73        if raw.is_null() {
74            values.push(Value::Null);
75            continue;
76        }
77        let name = col.type_info().name().to_string();
78        let v = match name.as_str() {
79            "BOOL" => Value::Bool(row.try_get::<bool, _>(i).map_err(classify)?),
80            "INT2" => Value::Int(i64::from(row.try_get::<i16, _>(i).map_err(classify)?)),
81            "INT4" => Value::Int(i64::from(row.try_get::<i32, _>(i).map_err(classify)?)),
82            "INT8" => Value::Int(row.try_get::<i64, _>(i).map_err(classify)?),
83            "FLOAT4" => Value::Float(f64::from(row.try_get::<f32, _>(i).map_err(classify)?)),
84            "FLOAT8" => Value::Float(row.try_get::<f64, _>(i).map_err(classify)?),
85            "TEXT" | "VARCHAR" | "NAME" | "BPCHAR" => {
86                Value::Text(row.try_get::<String, _>(i).map_err(classify)?)
87            }
88            "BYTEA" => Value::Bytes(row.try_get::<Vec<u8>, _>(i).map_err(classify)?),
89            other => {
90                return Err(RelError::Unsupported(format!(
91                    "column {:?} has type {other}, which Value cannot carry; use PgBackend::pool",
92                    col.name()
93                )));
94            }
95        };
96        values.push(v);
97    }
98    Ok(Row::new(values))
99}
100
101/// A PostgreSQL database behind an sqlx pool.
102#[derive(Debug, Clone)]
103pub struct PgBackend {
104    pool: sqlx::PgPool,
105    version: String,
106}
107
108impl PgBackend {
109    /// Connect with default pool settings and read the server version.
110    ///
111    /// Prefer [`PgBackend::connect_secret`]: a `&str` URL is one `Debug` print from a log file.
112    pub async fn connect(url: &str) -> Result<Self, RelError> {
113        let pool = PgPoolOptions::new()
114            .max_connections(16)
115            .connect(url)
116            .await
117            .map_err(classify)?;
118        Self::from_pool(pool).await
119    }
120
121    /// Connect with a connection string held as a [`persistant_relational::ConnectionSecret`]:
122    /// resolved here, never printed, never part of an error.
123    pub async fn connect_secret(
124        secret: &persistant_relational::ConnectionSecret,
125    ) -> Result<Self, RelError> {
126        let url = secret.resolve()?;
127        Self::connect(url.expose()).await
128    }
129
130    /// Wrap an existing pool (a program that already owns one keeps it).
131    pub async fn from_pool(pool: sqlx::PgPool) -> Result<Self, RelError> {
132        let full: String = sqlx::query_scalar("SHOW server_version")
133            .fetch_one(&pool)
134            .await
135            .map_err(classify)?;
136        // "16.15 (Debian 16.15-1.pgdg13+2)" -> "16.15"
137        let version = full.split_whitespace().next().unwrap_or("").to_string();
138        Ok(PgBackend { pool, version })
139    }
140
141    /// The concrete pool: for `sqlx::query!` and anything this layer does not carry.
142    pub fn pool(&self) -> &sqlx::PgPool {
143        &self.pool
144    }
145}
146
147impl RelationalBackend for PgBackend {
148    type Tx<'a> = PgTx<'a>;
149
150    fn backend(&self) -> &str {
151        "postgres"
152    }
153
154    fn version(&self) -> &str {
155        &self.version
156    }
157
158    fn dialect(&self) -> Dialect {
159        Dialect::Postgres
160    }
161
162    async fn execute(&self, sql: &str, params: &[Value]) -> Result<u64, RelError> {
163        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
164        q.execute(&self.pool)
165            .await
166            .map(|r| r.rows_affected())
167            .map_err(classify)
168    }
169
170    async fn query(&self, sql: &str, params: &[Value]) -> Result<Vec<Row>, RelError> {
171        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
172        let rows = q.fetch_all(&self.pool).await.map_err(classify)?;
173        rows.iter().map(decode).collect()
174    }
175
176    async fn begin(&self) -> Result<PgTx<'_>, RelError> {
177        Ok(PgTx {
178            tx: self.pool.begin().await.map_err(classify)?,
179        })
180    }
181}
182
183/// A PostgreSQL transaction.
184#[derive(Debug)]
185pub struct PgTx<'a> {
186    tx: sqlx::Transaction<'a, Postgres>,
187}
188
189impl RelationalTx for PgTx<'_> {
190    async fn execute(&mut self, sql: &str, params: &[Value]) -> Result<u64, RelError> {
191        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
192        q.execute(&mut *self.tx)
193            .await
194            .map(|r| r.rows_affected())
195            .map_err(classify)
196    }
197
198    async fn query(&mut self, sql: &str, params: &[Value]) -> Result<Vec<Row>, RelError> {
199        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
200        let rows = q.fetch_all(&mut *self.tx).await.map_err(classify)?;
201        rows.iter().map(decode).collect()
202    }
203
204    async fn commit(self) -> Result<(), RelError> {
205        self.tx.commit().await.map_err(classify)
206    }
207
208    async fn rollback(self) -> Result<(), RelError> {
209        self.tx.rollback().await.map_err(classify)
210    }
211}
persistant_sqlx/lib.rs

persistant_sqlx/
lib.rs
