Database Portability

Laterite runs on Postgres, MySQL or SQLite, chosen by the connection URL. Migrations and queries are written once, through sea-query over sqlx::Any.

Write a migration

use laterite_core::strata::*;

One import brings the Migration trait, async_trait, the schema and query builders, Db, and the polyfills. lat make:migration <description> writes a new file with it.

One migration per file under src/migrations/, named m<NNNN>_<description>.rs, declaring pub struct Migration with a stable name, an up and an optional down. mod.rs lists them in apply order:

laterite_core::migration_set! {
    module_id: "acme.blog",
    m0001_create_posts,
    m0002_create_comments,
}

Append at the end. Never reorder or rename a shipped entry: applied migrations are tracked by (module_id, name).

Use portable types

use laterite_core::{bool_col, AnyRowExt};

Table::create()
    .table(Article::Table)
    .col(bool_col(Article::Published).not_null().default(0));

let published: bool = row.get_bool("published")?;
let title: String = row.get_text("title")?;

Ids are bigint auto-increment; an insert never sets one. Canonicalise a user-facing unique key, lower-cased and trimmed, on write and on lookup: MySQL compares case-insensitively.

Write a query

use laterite_core::strata::*;

let stmt = Query::select()
    .column(Article::Title)
    .from(Article::Table)
    .and_where(Expr::col(Article::Published).eq(true))
    .to_owned();
let (sql, values) = build(db.backend, &stmt);
let rows = bind_values(sqlx::query(&sql), values).fetch_all(&db.pool).await?;

Never hand-write SQL with ? placeholders. db is a laterite_core::Db: the pool paired with its backend.

Differences the helpers do not hide