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
17#[cfg(feature = "mysql")]
18pub use mysql::{MysqlBackend, MysqlTx};
19pub use options::{ConnectOptions, TlsPolicy};
20pub use persistant_relational::{MigrateError, MigrateReport, Migrates, Migration};
21#[cfg(feature = "sqlite")]
22pub use sqlite::{SqliteBackend, SqliteTx};
23
24use persistant_relational::{
25    Dialect, Isolation, RelError, RelationalBackend, RelationalTx, Row, Value,
26};
27use sqlx::postgres::{PgArguments, PgPoolOptions, PgRow};
28use sqlx::query::Query;
29use sqlx::{Column, Postgres, Row as SqlxRow, TypeInfo, ValueRef};
30
31/// Classify an sqlx error by SQLSTATE (https://www.postgresql.org/docs/current/errcodes-appendix.html).
32pub(crate) fn classify(e: sqlx::Error) -> RelError {
33    match &e {
34        sqlx::Error::Database(db) => {
35            let constraint = db.constraint().map(str::to_string);
36            match db.code().as_deref() {
37                Some("23505") => RelError::UniqueViolation { constraint },
38                Some("23503") => RelError::ForeignKeyViolation { constraint },
39                Some("23514") | Some("23502") => RelError::CheckViolation { constraint },
40                Some("40001") => RelError::Serialization,
41                Some("40P01") => RelError::Deadlock,
42                Some(c) if c.starts_with("08") || c.starts_with("57P") => {
43                    RelError::Unavailable(e.to_string())
44                }
45                _ => RelError::Backend(e.to_string()),
46            }
47        }
48        sqlx::Error::Io(_) | sqlx::Error::PoolTimedOut | sqlx::Error::PoolClosed => {
49            RelError::Unavailable(e.to_string())
50        }
51        _ => RelError::Backend(e.to_string()),
52    }
53}
54
55/// A `NULL` whose type the server infers from the statement. Binding `Option::<String>::None` sends
56/// the type `text`, which the server rejects for a `bigint` column (`expression is of type text`) the
57/// first time a pooled connection prepares that statement, and not on one that already has: a failure
58/// that depends on which connection the pool hands out. Type OID 0 means "unspecified".
59struct UntypedNull;
60
61impl sqlx::Type<Postgres> for UntypedNull {
62    fn type_info() -> sqlx::postgres::PgTypeInfo {
63        sqlx::postgres::PgTypeInfo::with_oid(sqlx::postgres::types::Oid(0))
64    }
65
66    fn compatible(_: &sqlx::postgres::PgTypeInfo) -> bool {
67        true
68    }
69}
70
71impl<'q> sqlx::Encode<'q, Postgres> for UntypedNull {
72    fn encode_by_ref(
73        &self,
74        _: &mut sqlx::postgres::PgArgumentBuffer,
75    ) -> Result<sqlx::encode::IsNull, sqlx::error::BoxDynError> {
76        Ok(sqlx::encode::IsNull::Yes)
77    }
78}
79
80fn bind<'q>(
81    mut q: Query<'q, Postgres, PgArguments>,
82    params: &'q [Value],
83) -> Result<Query<'q, Postgres, PgArguments>, RelError> {
84    for p in params {
85        q = match p {
86            // A NULL of unspecified type: the server infers it from the statement.
87            Value::Null => q.bind(UntypedNull),
88            Value::Bool(b) => q.bind(*b),
89            Value::Int(n) => q.bind(*n),
90            Value::Float(f) => q.bind(*f),
91            Value::Text(s) => q.bind(s.as_str()),
92            Value::Bytes(b) => q.bind(b.as_slice()),
93            other => {
94                return Err(RelError::Unsupported(format!(
95                    "parameter {other:?} has no PostgreSQL binding in this driver"
96                )));
97            }
98        };
99    }
100    Ok(q)
101}
102
103fn decode(row: &PgRow) -> Result<Row, RelError> {
104    let mut values = Vec::with_capacity(row.columns().len());
105    for (i, col) in row.columns().iter().enumerate() {
106        let raw = row.try_get_raw(i).map_err(classify)?;
107        if raw.is_null() {
108            values.push(Value::Null);
109            continue;
110        }
111        let name = col.type_info().name().to_string();
112        let v = match name.as_str() {
113            "BOOL" => Value::Bool(row.try_get::<bool, _>(i).map_err(classify)?),
114            "INT2" => Value::Int(i64::from(row.try_get::<i16, _>(i).map_err(classify)?)),
115            "INT4" => Value::Int(i64::from(row.try_get::<i32, _>(i).map_err(classify)?)),
116            "INT8" => Value::Int(row.try_get::<i64, _>(i).map_err(classify)?),
117            "FLOAT4" => Value::Float(f64::from(row.try_get::<f32, _>(i).map_err(classify)?)),
118            "FLOAT8" => Value::Float(row.try_get::<f64, _>(i).map_err(classify)?),
119            "TEXT" | "VARCHAR" | "NAME" | "BPCHAR" => {
120                Value::Text(row.try_get::<String, _>(i).map_err(classify)?)
121            }
122            "BYTEA" => Value::Bytes(row.try_get::<Vec<u8>, _>(i).map_err(classify)?),
123            other => {
124                return Err(RelError::Unsupported(format!(
125                    "column {:?} has type {other}, which Value cannot carry; use PgBackend::pool",
126                    col.name()
127                )));
128            }
129        };
130        values.push(v);
131    }
132    Ok(Row::new(values))
133}
134
135/// A PostgreSQL database behind an sqlx pool.
136#[derive(Debug, Clone)]
137pub struct PgBackend {
138    pool: sqlx::PgPool,
139    version: String,
140}
141
142impl PgBackend {
143    /// Connect with default pool settings and read the server version.
144    ///
145    /// Prefer [`PgBackend::connect_secret`]: a `&str` URL is one `Debug` print from a log file.
146    pub async fn connect(url: &str) -> Result<Self, RelError> {
147        let pool = PgPoolOptions::new()
148            .max_connections(16)
149            .connect(url)
150            .await
151            .map_err(classify)?;
152        Self::from_pool(pool).await
153    }
154
155    /// Connect with a connection string held as a [`persistant_relational::ConnectionSecret`]:
156    /// resolved here, never printed, never part of an error.
157    pub async fn connect_secret(
158        secret: &persistant_relational::ConnectionSecret,
159    ) -> Result<Self, RelError> {
160        let url = secret.resolve()?;
161        Self::connect(url.expose()).await
162    }
163
164    /// Wrap an existing pool (a program that already owns one keeps it).
165    pub async fn from_pool(pool: sqlx::PgPool) -> Result<Self, RelError> {
166        let full: String = sqlx::query_scalar("SHOW server_version")
167            .fetch_one(&pool)
168            .await
169            .map_err(classify)?;
170        // "16.15 (Debian 16.15-1.pgdg13+2)" -> "16.15"
171        let version = full.split_whitespace().next().unwrap_or("").to_string();
172        Ok(PgBackend { pool, version })
173    }
174
175    /// The concrete pool: for `sqlx::query!` and anything this layer does not carry.
176    pub fn pool(&self) -> &sqlx::PgPool {
177        &self.pool
178    }
179}
180
181impl RelationalBackend for PgBackend {
182    type Tx<'a> = PgTx<'a>;
183
184    fn backend(&self) -> &str {
185        "postgres"
186    }
187
188    fn version(&self) -> &str {
189        &self.version
190    }
191
192    fn dialect(&self) -> Dialect {
193        Dialect::Postgres
194    }
195
196    async fn execute(&self, sql: &str, params: &[Value]) -> Result<u64, RelError> {
197        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
198        q.execute(&self.pool)
199            .await
200            .map(|r| r.rows_affected())
201            .map_err(classify)
202    }
203
204    async fn query(&self, sql: &str, params: &[Value]) -> Result<Vec<Row>, RelError> {
205        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
206        let rows = q.fetch_all(&self.pool).await.map_err(classify)?;
207        rows.iter().map(decode).collect()
208    }
209
210    async fn begin(&self, isolation: Isolation) -> Result<PgTx<'_>, RelError> {
211        let statement = match isolation {
212            Isolation::ReadCommitted => "BEGIN",
213            Isolation::RepeatableRead => "BEGIN ISOLATION LEVEL REPEATABLE READ",
214            Isolation::Serializable => "BEGIN ISOLATION LEVEL SERIALIZABLE",
215            other => return Err(RelError::Unsupported(format!("isolation level {other:?}"))),
216        };
217        Ok(PgTx {
218            tx: self.pool.begin_with(statement).await.map_err(classify)?,
219        })
220    }
221}
222
223/// A PostgreSQL transaction.
224#[derive(Debug)]
225pub struct PgTx<'a> {
226    tx: sqlx::Transaction<'a, Postgres>,
227}
228
229impl RelationalTx for PgTx<'_> {
230    async fn execute(&mut self, sql: &str, params: &[Value]) -> Result<u64, RelError> {
231        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
232        q.execute(&mut *self.tx)
233            .await
234            .map(|r| r.rows_affected())
235            .map_err(classify)
236    }
237
238    async fn query(&mut self, sql: &str, params: &[Value]) -> Result<Vec<Row>, RelError> {
239        let q = bind(sqlx::query(sqlx::AssertSqlSafe(sql.to_string())), params)?;
240        let rows = q.fetch_all(&mut *self.tx).await.map_err(classify)?;
241        rows.iter().map(decode).collect()
242    }
243
244    async fn commit(self) -> Result<(), RelError> {
245        self.tx.commit().await.map_err(classify)
246    }
247
248    async fn rollback(self) -> Result<(), RelError> {
249        self.tx.rollback().await.map_err(classify)
250    }
251}
persistant_sqlx/lib.rs

persistant_sqlx/
lib.rs
