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;
11#[cfg(feature = "mysql")]
12mod mysql;
13mod options;
14#[cfg(feature = "sqlite")]
15mod sqlite;
16
17pub use migrate::{MigrateError, MigrateReport, Migration};
18#[cfg(feature = "mysql")]
19pub use mysql::{MysqlBackend, MysqlTx};
20pub use options::{ConnectOptions, TlsPolicy};
21#[cfg(feature = "sqlite")]
22pub use sqlite::{SqliteBackend, SqliteTx};
23
24use persistant_relational::{Dialect, RelError, RelationalBackend, RelationalTx, Row, Value};
25use sqlx::postgres::{PgArguments, PgPoolOptions, PgRow};
26use sqlx::query::Query;
27use sqlx::{Column, Postgres, Row as SqlxRow, TypeInfo, ValueRef};
28
29/// Classify an sqlx error by SQLSTATE (https://www.postgresql.org/docs/current/errcodes-appendix.html).
30pub(crate) fn classify(e: sqlx::Error) -> RelError {
31    match &e {
32        sqlx::Error::Database(db) => {
33            let constraint = db.constraint().map(str::to_string);
34            match db.code().as_deref() {
35                Some("23505") => RelError::UniqueViolation { constraint },
36                Some("23503") => RelError::ForeignKeyViolation { constraint },
37                Some("23514") | Some("23502") => RelError::CheckViolation { constraint },
38                Some("40001") => RelError::Serialization,
39                Some("40P01") => RelError::Deadlock,
40                Some(c) if c.starts_with("08") || c.starts_with("57P") => {
41                    RelError::Unavailable(e.to_string())
42                }
43                _ => RelError::Backend(e.to_string()),
44            }
45        }
46        sqlx::Error::Io(_) | sqlx::Error::PoolTimedOut | sqlx::Error::PoolClosed => {
47            RelError::Unavailable(e.to_string())
48        }
49        _ => RelError::Backend(e.to_string()),
50    }
51}
52
53fn bind<'q>(
54    mut q: Query<'q, Postgres, PgArguments>,
55    params: &'q [Value],
56) -> Result<Query<'q, Postgres, PgArguments>, RelError> {
57    for p in params {
58        q = match p {
59            // A typed NULL: PostgreSQL needs a type to infer parameter types; text works for the
60            // statements this layer issues. A caller needing another NULL type casts in SQL.
61            Value::Null => q.bind(Option::<String>::None),
62            Value::Bool(b) => q.bind(*b),
63            Value::Int(n) => q.bind(*n),
64            Value::Float(f) => q.bind(*f),
65            Value::Text(s) => q.bind(s.as_str()),
66            Value::Bytes(b) => q.bind(b.as_slice()),
67            other => {
68                return Err(RelError::Unsupported(format!(
69                    "parameter {other:?} has no PostgreSQL binding in this driver"
70                )));
71            }
72        };
73    }
74    Ok(q)
75}
76
77fn decode(row: &PgRow) -> Result<Row, RelError> {
78    let mut values = Vec::with_capacity(row.columns().len());
79    for (i, col) in row.columns().iter().enumerate() {
80        let raw = row.try_get_raw(i).map_err(classify)?;
81        if raw.is_null() {
82            values.push(Value::Null);
83            continue;
84        }
85        let name = col.type_info().name().to_string();
86        let v = match name.as_str() {
87            "BOOL" => Value::Bool(row.try_get::<bool, _>(i).map_err(classify)?),
88            "INT2" => Value::Int(i64::from(row.try_get::<i16, _>(i).map_err(classify)?)),
89            "INT4" => Value::Int(i64::from(row.try_get::<i32, _>(i).map_err(classify)?)),
90            "INT8" => Value::Int(row.try_get::<i64, _>(i).map_err(classify)?),
91            "FLOAT4" => Value::Float(f64::from(row.try_get::<f32, _>(i).map_err(classify)?)),
92            "FLOAT8" => Value::Float(row.try_get::<f64, _>(i).map_err(classify)?),
93            "TEXT" | "VARCHAR" | "NAME" | "BPCHAR" => {
94                Value::Text(row.try_get::<String, _>(i).map_err(classify)?)
95            }
96            "BYTEA" => Value::Bytes(row.try_get::<Vec<u8>, _>(i).map_err(classify)?),
97            other => {
98                return Err(RelError::Unsupported(format!(
99                    "column {:?} has type {other}, which Value cannot carry; use PgBackend::pool",
100                    col.name()
101                )));
102            }
103        };
104        values.push(v);
105    }
106    Ok(Row::new(values))
107}
108
109/// A PostgreSQL database behind an sqlx pool.
110#[derive(Debug, Clone)]
111pub struct PgBackend {
112    pool: sqlx::PgPool,
113    version: String,
114}
115
116impl PgBackend {
117    /// Connect with default pool settings and read the server version.
118    ///
119    /// Prefer [`PgBackend::connect_secret`]: a `&str` URL is one `Debug` print from a log file.
120    pub async fn connect(url: &str) -> Result<Self, RelError> {
121        let pool = PgPoolOptions::new()
122            .max_connections(16)
123            .connect(url)
124            .await
125            .map_err(classify)?;
126        Self::from_pool(pool).await
127    }
128
129    /// Connect with a connection string held as a [`persistant_relational::ConnectionSecret`]:
130    /// resolved here, never printed, never part of an error.
131    pub async fn connect_secret(
132        secret: &persistant_relational::ConnectionSecret,
133    ) -> Result<Self, RelError> {
134        let url = secret.resolve()?;
135        Self::connect(url.expose()).await
136    }
137
138    /// Wrap an existing pool (a program that already owns one keeps it).
139    pub async fn from_pool(pool: sqlx::PgPool) -> Result<Self, RelError> {
140        let full: String = sqlx::query_scalar("SHOW server_version")
141            .fetch_one(&pool)
142            .await
143            .map_err(classify)?;
144        // "16.15 (Debian 16.15-1.pgdg13+2)" -> "16.15"
145        let version = full.split_whitespace().next().unwrap_or("").to_string();
146        Ok(PgBackend { pool, version })
147    }
148
149    /// The concrete pool: for `sqlx::query!` and anything this layer does not carry.
150    pub fn pool(&self) -> &sqlx::PgPool {
151        &self.pool
152    }
153}
154
155impl RelationalBackend for PgBackend {
156    type Tx<'a> = PgTx<'a>;
157
158    fn backend(&self) -> &str {
159        "postgres"
160    }
161
162    fn version(&self) -> &str {
163        &self.version
164    }
165
166    fn dialect(&self) -> Dialect {
167        Dialect::Postgres
168    }
169
170    async fn execute(&self, sql: &str, params: &[Value]) -> Result<u64, RelError> {
171        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
172        q.execute(&self.pool)
173            .await
174            .map(|r| r.rows_affected())
175            .map_err(classify)
176    }
177
178    async fn query(&self, sql: &str, params: &[Value]) -> Result<Vec<Row>, RelError> {
179        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
180        let rows = q.fetch_all(&self.pool).await.map_err(classify)?;
181        rows.iter().map(decode).collect()
182    }
183
184    async fn begin(&self) -> Result<PgTx<'_>, RelError> {
185        Ok(PgTx {
186            tx: self.pool.begin().await.map_err(classify)?,
187        })
188    }
189}
190
191/// A PostgreSQL transaction.
192#[derive(Debug)]
193pub struct PgTx<'a> {
194    tx: sqlx::Transaction<'a, Postgres>,
195}
196
197impl RelationalTx for PgTx<'_> {
198    async fn execute(&mut self, sql: &str, params: &[Value]) -> Result<u64, RelError> {
199        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
200        q.execute(&mut *self.tx)
201            .await
202            .map(|r| r.rows_affected())
203            .map_err(classify)
204    }
205
206    async fn query(&mut self, sql: &str, params: &[Value]) -> Result<Vec<Row>, RelError> {
207        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
208        let rows = q.fetch_all(&mut *self.tx).await.map_err(classify)?;
209        rows.iter().map(decode).collect()
210    }
211
212    async fn commit(self) -> Result<(), RelError> {
213        self.tx.commit().await.map_err(classify)
214    }
215
216    async fn rollback(self) -> Result<(), RelError> {
217        self.tx.rollback().await.map_err(classify)
218    }
219}
persistant_sqlx/lib.rs

persistant_sqlx/
lib.rs
