gize_core/
dialect.rs

1//! The database dialect seam (ADR-015).
2//!
3//! Everything that differs between the supported databases — column types, primary-key
4//! generation, bind placeholders, pool types, integrity-error handling, and whether
5//! `RETURNING` is available — lives here, chosen from `stack.database` in the manifest.
6//! Postgres is the default and its output is byte-identical to the pre-seam generator; SQLite
7//! is the serverless second target; MySQL is the third (ADR-015 amendment).
8
9use crate::FieldType;
10
11/// A supported database dialect.
12#[derive(Debug, Clone, Copy, PartialEq, Eq)]
13pub enum Dialect {
14    Postgres,
15    Sqlite,
16    MySql,
17}
18
19impl Dialect {
20    /// Pick the dialect from the manifest's `stack.database` (`"sqlite"` → SQLite,
21    /// `"mysql"` → MySQL, else the Postgres default).
22    pub fn from_database(database: &str) -> Self {
23        if database.eq_ignore_ascii_case("sqlite") {
24            Dialect::Sqlite
25        } else if database.eq_ignore_ascii_case("mysql") {
26            Dialect::MySql
27        } else {
28            Dialect::Postgres
29        }
30    }
31
32    /// The `id` primary-key column DDL (no trailing comma). Postgres generates the UUID in the
33    /// database; SQLite and MySQL have no UUID generator, so the app supplies it on insert.
34    /// MySQL uses `BINARY(16)` — the type sqlx encodes/decodes `uuid::Uuid` to natively, so the
35    /// generated model, binds and `FromRow` stay uniform across dialects.
36    pub fn id_pk_ddl(self) -> &'static str {
37        match self {
38            Dialect::Postgres => "id UUID PRIMARY KEY DEFAULT gen_random_uuid()",
39            Dialect::Sqlite => "id TEXT PRIMARY KEY",
40            Dialect::MySql => "id BINARY(16) PRIMARY KEY",
41        }
42    }
43
44    /// Whether the app must generate `id` on insert (SQLite, MySQL) rather than the database
45    /// (Postgres).
46    pub fn app_generates_id(self) -> bool {
47        matches!(self, Dialect::Sqlite | Dialect::MySql)
48    }
49
50    /// Whether the dialect supports `INSERT/UPDATE ... RETURNING *`. Postgres and SQLite do;
51    /// MySQL does not, so the generated repository re-reads the row with a `SELECT` after
52    /// writing (it knows the `id`, which the app generates).
53    pub fn supports_returning(self) -> bool {
54        !matches!(self, Dialect::MySql)
55    }
56
57    /// The SQL column type for a scalar field.
58    pub fn column_type(self, ty: FieldType) -> &'static str {
59        match self {
60            // Postgres keeps the canonical mapping (ADR-011).
61            Dialect::Postgres => ty.sql_type(),
62            // SQLite storage classes: TEXT / INTEGER / REAL. UUIDs are stored by sqlx as BLOB
63            // but a TEXT-affinity column holds them fine; timestamps are ISO-8601 TEXT.
64            Dialect::Sqlite => match ty {
65                FieldType::String | FieldType::Uuid | FieldType::DateTime => "TEXT",
66                FieldType::Bool | FieldType::I32 | FieldType::I64 => "INTEGER",
67                FieldType::F64 => "REAL",
68            },
69            // MySQL. `String` is `VARCHAR(255)` (indexable, unlike `TEXT` without a prefix
70            // length, so `email UNIQUE` works); UUIDs are `BINARY(16)` (sqlx's native mapping).
71            Dialect::MySql => match ty {
72                FieldType::String => "VARCHAR(255)",
73                FieldType::Uuid => "BINARY(16)",
74                FieldType::DateTime => "DATETIME",
75                FieldType::Bool => "BOOLEAN",
76                FieldType::I32 => "INT",
77                FieldType::I64 => "BIGINT",
78                FieldType::F64 => "DOUBLE",
79            },
80        }
81    }
82
83    /// The `TYPE NOT NULL DEFAULT ...` fragment for the `created_at`/`updated_at` columns.
84    pub fn timestamp_type_default(self) -> &'static str {
85        match self {
86            Dialect::Postgres => "TIMESTAMPTZ NOT NULL DEFAULT now()",
87            // RFC-3339 with a `Z` so sqlx decodes it straight into `DateTime<Utc>`.
88            Dialect::Sqlite => "TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))",
89            Dialect::MySql => "DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP",
90        }
91    }
92
93    /// The SQL expression for "now" used in `UPDATE ... SET updated_at = <now>`.
94    pub fn now_expr(self) -> &'static str {
95        match self {
96            Dialect::Postgres => "now()",
97            Dialect::Sqlite => "strftime('%Y-%m-%dT%H:%M:%fZ','now')",
98            Dialect::MySql => "now()",
99        }
100    }
101
102    /// A bind placeholder for parameter `n` (1-based): `$n` on Postgres, `?n` on SQLite, and a
103    /// bare positional `?` on MySQL (its protocol binds positionally, without an index).
104    pub fn placeholder(self, n: usize) -> String {
105        match self {
106            Dialect::Postgres => format!("${n}"),
107            Dialect::Sqlite => format!("?{n}"),
108            Dialect::MySql => "?".to_string(),
109        }
110    }
111
112    /// The sqlx pool type used in generated code.
113    pub fn pool_type(self) -> &'static str {
114        match self {
115            Dialect::Postgres => "PgPool",
116            Dialect::Sqlite => "SqlitePool",
117            Dialect::MySql => "MySqlPool",
118        }
119    }
120
121    /// The sqlx pool-options type.
122    pub fn pool_options(self) -> &'static str {
123        match self {
124            Dialect::Postgres => "PgPoolOptions",
125            Dialect::Sqlite => "SqlitePoolOptions",
126            Dialect::MySql => "MySqlPoolOptions",
127        }
128    }
129
130    /// The sqlx submodule the pool types live in (`sqlx::postgres` / `sqlx::sqlite` /
131    /// `sqlx::mysql`).
132    pub fn sqlx_module(self) -> &'static str {
133        match self {
134            Dialect::Postgres => "postgres",
135            Dialect::Sqlite => "sqlite",
136            Dialect::MySql => "mysql",
137        }
138    }
139
140    /// The sqlx feature to enable in the generated `Cargo.toml`.
141    pub fn sqlx_feature(self) -> &'static str {
142        match self {
143            Dialect::Postgres => "postgres",
144            Dialect::Sqlite => "sqlite",
145            Dialect::MySql => "mysql",
146        }
147    }
148
149    /// The full `if let sqlx::Error::Database(..) { .. }` block, inside `From<sqlx::Error>`, that
150    /// classifies a database integrity error into `Error::Conflict` (unique violation) or
151    /// `Error::ForeignKey`. Indented to sit at the 8-space body level of the `from` function.
152    ///
153    /// Postgres and SQLite expose distinct codes through `.code()` (SQLSTATE / extended result
154    /// code). MySQL collapses both to SQLSTATE `23000`, so it must read the numeric error code
155    /// (`1062` duplicate key; `1451`, `1452`, `1216`, `1217` foreign key) off the concrete
156    /// `MySqlDatabaseError`.
157    pub fn integrity_error_mapping(self) -> String {
158        let inner = match self {
159            // Postgres SQLSTATE; SQLite extended result codes (2067 unique, 787 foreign key).
160            Dialect::Postgres | Dialect::Sqlite => {
161                let (unique, fk) = if self == Dialect::Postgres {
162                    ("23505", "23503")
163                } else {
164                    ("2067", "787")
165                };
166                [
167                    "            match db.code().as_deref() {".to_string(),
168                    format!("                Some(\"{unique}\") => return Error::Conflict, // unique violation"),
169                    format!("                Some(\"{fk}\") => return Error::ForeignKey, // foreign-key violation"),
170                    "                _ => {}".to_string(),
171                    "            }".to_string(),
172                ]
173                .join("\n")
174            }
175            Dialect::MySql => [
176                "            if let Some(mysql) = db.try_downcast_ref::<sqlx::mysql::MySqlDatabaseError>() {",
177                "                match mysql.number() {",
178                "                    1062 => return Error::Conflict, // duplicate key",
179                // 1452/1216: a child row names a missing parent; 1451/1217: a parent row is
180                // still referenced (e.g. deleting a user who still has posts).
181                "                    1451 | 1452 | 1216 | 1217 => return Error::ForeignKey, // foreign-key violation",
182                "                    _ => {}",
183                "                }",
184                "            }",
185            ]
186            .join("\n"),
187        };
188        format!("        if let sqlx::Error::Database(ref db) = error {{\n{inner}\n        }}")
189    }
190
191    /// An example `DATABASE_URL` for `.env.example`.
192    pub fn example_url(self, project: &str) -> String {
193        match self {
194            Dialect::Postgres => {
195                format!("postgres://postgres:postgres@localhost:5432/{project}")
196            }
197            Dialect::Sqlite => format!("sqlite://{project}.db?mode=rwc"),
198            Dialect::MySql => format!("mysql://root:root@localhost:3306/{project}"),
199        }
200    }
201}
202
203#[cfg(test)]
204mod tests {
205    use super::*;
206
207    #[test]
208    fn postgres_output_is_the_canonical_mapping() {
209        let d = Dialect::from_database("postgres");
210        assert_eq!(
211            d.id_pk_ddl(),
212            "id UUID PRIMARY KEY DEFAULT gen_random_uuid()"
213        );
214        assert_eq!(d.column_type(FieldType::String), "TEXT");
215        assert_eq!(d.column_type(FieldType::DateTime), "TIMESTAMPTZ");
216        assert_eq!(d.placeholder(3), "$3");
217        assert!(!d.app_generates_id());
218        assert_eq!(d.pool_type(), "PgPool");
219    }
220
221    #[test]
222    fn sqlite_maps_types_and_placeholders() {
223        let d = Dialect::from_database("sqlite");
224        assert_eq!(d.id_pk_ddl(), "id TEXT PRIMARY KEY");
225        assert_eq!(d.column_type(FieldType::Uuid), "TEXT");
226        assert_eq!(d.column_type(FieldType::Bool), "INTEGER");
227        assert_eq!(d.column_type(FieldType::F64), "REAL");
228        assert_eq!(d.placeholder(2), "?2");
229        assert!(d.app_generates_id());
230        assert_eq!(d.pool_type(), "SqlitePool");
231        assert_eq!(d.sqlx_feature(), "sqlite");
232    }
233
234    #[test]
235    fn mysql_uses_binary_uuid_positional_binds_and_no_returning() {
236        let d = Dialect::from_database("mysql");
237        assert_eq!(d.id_pk_ddl(), "id BINARY(16) PRIMARY KEY");
238        assert!(d.app_generates_id());
239        assert!(!d.supports_returning());
240        assert_eq!(d.column_type(FieldType::String), "VARCHAR(255)");
241        assert_eq!(d.column_type(FieldType::Uuid), "BINARY(16)");
242        assert_eq!(d.column_type(FieldType::DateTime), "DATETIME");
243        assert_eq!(d.column_type(FieldType::Bool), "BOOLEAN");
244        // MySQL binds positionally: every placeholder is a bare `?`.
245        assert_eq!(d.placeholder(1), "?");
246        assert_eq!(d.placeholder(4), "?");
247        assert_eq!(d.pool_type(), "MySqlPool");
248        assert_eq!(d.sqlx_feature(), "mysql");
249        // Its integrity mapping reads the numeric error code, not SQLSTATE.
250        let mapping = d.integrity_error_mapping();
251        assert!(mapping.contains("MySqlDatabaseError"));
252        assert!(mapping.contains("1062 => return Error::Conflict"));
253        assert!(mapping.contains("1451 | 1452 | 1216 | 1217 => return Error::ForeignKey"));
254    }
255
256    #[test]
257    fn returning_dialects_map_codes_via_sqlstate() {
258        // Postgres and SQLite support RETURNING and classify errors by `.code()`.
259        for d in [Dialect::Postgres, Dialect::Sqlite] {
260            assert!(d.supports_returning());
261            assert!(d.integrity_error_mapping().contains("db.code()"));
262        }
263    }
264
265    #[test]
266    fn defaults_to_postgres() {
267        assert_eq!(Dialect::from_database("mysql"), Dialect::MySql);
268        assert_eq!(Dialect::from_database("cockroach"), Dialect::Postgres);
269        assert_eq!(Dialect::from_database(""), Dialect::Postgres);
270    }
271}
gize_core/dialect.rs

gize_core/
dialect.rs
