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
53/// A `NULL` whose type the server infers from the statement. Binding `Option::<String>::None` sends
54/// the type `text`, which the server rejects for a `bigint` column (`expression is of type text`) the
55/// first time a pooled connection prepares that statement, and not on one that already has: a failure
56/// that depends on which connection the pool hands out. Type OID 0 means "unspecified".
57struct UntypedNull;
58
59impl sqlx::Type<Postgres> for UntypedNull {
60    fn type_info() -> sqlx::postgres::PgTypeInfo {
61        sqlx::postgres::PgTypeInfo::with_oid(sqlx::postgres::types::Oid(0))
62    }
63
64    fn compatible(_: &sqlx::postgres::PgTypeInfo) -> bool {
65        true
66    }
67}
68
69impl<'q> sqlx::Encode<'q, Postgres> for UntypedNull {
70    fn encode_by_ref(
71        &self,
72        _: &mut sqlx::postgres::PgArgumentBuffer,
73    ) -> Result<sqlx::encode::IsNull, sqlx::error::BoxDynError> {
74        Ok(sqlx::encode::IsNull::Yes)
75    }
76}
77
78fn bind<'q>(
79    mut q: Query<'q, Postgres, PgArguments>,
80    params: &'q [Value],
81) -> Result<Query<'q, Postgres, PgArguments>, RelError> {
82    for p in params {
83        q = match p {
84            // A NULL of unspecified type: the server infers it from the statement.
85            Value::Null => q.bind(UntypedNull),
86            Value::Bool(b) => q.bind(*b),
87            Value::Int(n) => q.bind(*n),
88            Value::Float(f) => q.bind(*f),
89            Value::Text(s) => q.bind(s.as_str()),
90            Value::Bytes(b) => q.bind(b.as_slice()),
91            other => {
92                return Err(RelError::Unsupported(format!(
93                    "parameter {other:?} has no PostgreSQL binding in this driver"
94                )));
95            }
96        };
97    }
98    Ok(q)
99}
100
101fn decode(row: &PgRow) -> Result<Row, RelError> {
102    let mut values = Vec::with_capacity(row.columns().len());
103    for (i, col) in row.columns().iter().enumerate() {
104        let raw = row.try_get_raw(i).map_err(classify)?;
105        if raw.is_null() {
106            values.push(Value::Null);
107            continue;
108        }
109        let name = col.type_info().name().to_string();
110        let v = match name.as_str() {
111            "BOOL" => Value::Bool(row.try_get::<bool, _>(i).map_err(classify)?),
112            "INT2" => Value::Int(i64::from(row.try_get::<i16, _>(i).map_err(classify)?)),
113            "INT4" => Value::Int(i64::from(row.try_get::<i32, _>(i).map_err(classify)?)),
114            "INT8" => Value::Int(row.try_get::<i64, _>(i).map_err(classify)?),
115            "FLOAT4" => Value::Float(f64::from(row.try_get::<f32, _>(i).map_err(classify)?)),
116            "FLOAT8" => Value::Float(row.try_get::<f64, _>(i).map_err(classify)?),
117            "TEXT" | "VARCHAR" | "NAME" | "BPCHAR" => {
118                Value::Text(row.try_get::<String, _>(i).map_err(classify)?)
119            }
120            "BYTEA" => Value::Bytes(row.try_get::<Vec<u8>, _>(i).map_err(classify)?),
121            other => {
122                return Err(RelError::Unsupported(format!(
123                    "column {:?} has type {other}, which Value cannot carry; use PgBackend::pool",
124                    col.name()
125                )));
126            }
127        };
128        values.push(v);
129    }
130    Ok(Row::new(values))
131}
132
133/// A PostgreSQL database behind an sqlx pool.
134#[derive(Debug, Clone)]
135pub struct PgBackend {
136    pool: sqlx::PgPool,
137    version: String,
138}
139
140impl PgBackend {
141    /// Connect with default pool settings and read the server version.
142    ///
143    /// Prefer [`PgBackend::connect_secret`]: a `&str` URL is one `Debug` print from a log file.
144    pub async fn connect(url: &str) -> Result<Self, RelError> {
145        let pool = PgPoolOptions::new()
146            .max_connections(16)
147            .connect(url)
148            .await
149            .map_err(classify)?;
150        Self::from_pool(pool).await
151    }
152
153    /// Connect with a connection string held as a [`persistant_relational::ConnectionSecret`]:
154    /// resolved here, never printed, never part of an error.
155    pub async fn connect_secret(
156        secret: &persistant_relational::ConnectionSecret,
157    ) -> Result<Self, RelError> {
158        let url = secret.resolve()?;
159        Self::connect(url.expose()).await
160    }
161
162    /// Wrap an existing pool (a program that already owns one keeps it).
163    pub async fn from_pool(pool: sqlx::PgPool) -> Result<Self, RelError> {
164        let full: String = sqlx::query_scalar("SHOW server_version")
165            .fetch_one(&pool)
166            .await
167            .map_err(classify)?;
168        // "16.15 (Debian 16.15-1.pgdg13+2)" -> "16.15"
169        let version = full.split_whitespace().next().unwrap_or("").to_string();
170        Ok(PgBackend { pool, version })
171    }
172
173    /// The concrete pool: for `sqlx::query!` and anything this layer does not carry.
174    pub fn pool(&self) -> &sqlx::PgPool {
175        &self.pool
176    }
177}
178
179impl RelationalBackend for PgBackend {
180    type Tx<'a> = PgTx<'a>;
181
182    fn backend(&self) -> &str {
183        "postgres"
184    }
185
186    fn version(&self) -> &str {
187        &self.version
188    }
189
190    fn dialect(&self) -> Dialect {
191        Dialect::Postgres
192    }
193
194    async fn execute(&self, sql: &str, params: &[Value]) -> Result<u64, RelError> {
195        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
196        q.execute(&self.pool)
197            .await
198            .map(|r| r.rows_affected())
199            .map_err(classify)
200    }
201
202    async fn query(&self, sql: &str, params: &[Value]) -> Result<Vec<Row>, RelError> {
203        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
204        let rows = q.fetch_all(&self.pool).await.map_err(classify)?;
205        rows.iter().map(decode).collect()
206    }
207
208    async fn begin(&self) -> Result<PgTx<'_>, RelError> {
209        Ok(PgTx {
210            tx: self.pool.begin().await.map_err(classify)?,
211        })
212    }
213}
214
215/// A PostgreSQL transaction.
216#[derive(Debug)]
217pub struct PgTx<'a> {
218    tx: sqlx::Transaction<'a, Postgres>,
219}
220
221impl RelationalTx for PgTx<'_> {
222    async fn execute(&mut self, sql: &str, params: &[Value]) -> Result<u64, RelError> {
223        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
224        q.execute(&mut *self.tx)
225            .await
226            .map(|r| r.rows_affected())
227            .map_err(classify)
228    }
229
230    async fn query(&mut self, sql: &str, params: &[Value]) -> Result<Vec<Row>, RelError> {
231        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
232        let rows = q.fetch_all(&mut *self.tx).await.map_err(classify)?;
233        rows.iter().map(decode).collect()
234    }
235
236    async fn commit(self) -> Result<(), RelError> {
237        self.tx.commit().await.map_err(classify)
238    }
239
240    async fn rollback(self) -> Result<(), RelError> {
241        self.tx.rollback().await.map_err(classify)
242    }
243}
persistant_sqlx/lib.rs

persistant_sqlx/
lib.rs
