Crate ferro_orm 

ferro-orm

Atomic conditional updates and ORM primitives for the Ferro framework.

GuardedUpdate<E> compiles to a single UPDATE … WHERE … SQL statement, replacing the hand-rolled read → check → write pattern wherever a column’s value is conditionally mutated. The database is the authority on contention; the call site is race-free by construction.

Example

use ferro_orm::{GuardedUpdate, ColumnTrait};
use sea_orm::sea_query::Expr;

GuardedUpdate::new(inventory_units::Entity)
    .filter(inventory_units::Column::Id.eq(unit_id))
    .filter(inventory_units::Column::Quantity.gte(needed))
    .set_expr(
        inventory_units::Column::Quantity,
        Expr::col(inventory_units::Column::Quantity).sub(needed),
    )
    .exec_one(&txn)
    .await?;
// — exactly one row matched and was decremented atomically,
//   OR Err(NoRowsAffected) signalling capacity exhausted.

Atomicity guarantee (and its limit)

GuardedUpdate guarantees atomicity per statement, not per builder. A caller building .set_expr(qty - 1) and reading the resulting qty in a separate query without a transaction re-introduces a race. The crate’s job is to make the conditional UPDATE race-free; bracketing it in a transaction is the caller’s responsibility.

Structs

Expr

Helper to build a SimpleExpr.

GuardedUpdate

Enums

DbErr

An error from unsuccessful database operations

GuardedError

SimpleExpr

Represents a Simple Expression in SQL.

Value

Value variants

Traits

ColumnTrait

API for working with a Column. Mostly a wrapper of the identically named methods in sea_query::Expr

ConnectionTrait

The generic API for a database connection that can perform query or execute statements. It abstracts database connection and transaction

EntityTrait

An abstract base class for defining Entities.

IntoCondition