# surrealdb-adapter

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## Purpose

`SurrealDbAdapter` adapts a SurrealDB instance to the minimal `execute`/`query` interface required by `DatabaseMigrationStore` and migration context objects. Because SurrealDB uses named query variables rather than positional parameters, this adapter translates positional `params` arrays to `{ p0, p1, … }` named variable maps automatically. This allows the same migration SQL templates to work across SQLite (positional `?`) and SurrealDB (named `$p0`) by using a consistent calling convention.

## Features

- `query<T>(sql, params?)` — executes a SurrealDB query and returns typed results.
- `execute(sql, params?)` — executes a non-query statement; always returns `{ rowsAffected: 0 }` (SurrealDB does not expose row counts).
- Translates positional params array to named vars (`p0`, `p1`, …).
- Wraps errors in `MigrationError(MIGRATION.STORE_ERROR)` or `MIGRATION.FAILED`.

## Usage: Basic Example

```ts
import { SurrealDbAdapter } from "@suaveplan/migration";
import { DatabaseMigrationStore } from "@suaveplan/migration";
import Surreal from "surrealdb";

const db = new Surreal();
await db.connect("http://localhost:8000");

const adapter = new SurrealDbAdapter({ db });
const store = new DatabaseMigrationStore({ adapter });
```

## Usage: Advanced Example

```ts
import { SurrealDbAdapter } from "@suaveplan/migration";
import { MigrationRunner, MemoryMigrationStore } from "@suaveplan/migration";

const adapter = new SurrealDbAdapter({ db: surrealInstance });
const store = new MemoryMigrationStore(); // or DatabaseMigrationStore
const runner = new MigrationRunner({ migrations, store });
```

## API Reference

### `class SurrealDbAdapter`

**Constructor**: `(config: SurrealDbAdapterConfig)`

- `config.db` — object implementing `query<T>(sql, vars?): Promise<T[]>`.

### `query<T>(sql: string, params?: readonly unknown[]): Promise<T[]>`

Translates params to named vars and delegates to `db.query`. Returns an empty array if the result is not an array.

### `execute(sql: string, params?: readonly unknown[]): Promise<{ rowsAffected: number }>`

Executes SQL via `db.query`. Always returns `{ rowsAffected: 0 }`.

## Implementation Notes

SurrealDB's `query` method returns an array of result sets per SQL statement. This adapter flattens the outer array and returns the first result set. For multi-statement SQL, callers should split statements and call `query` for each.