feat: refactor tx API + add backing functions

- Consolidated transaction API to address a design flaw
  - Calling BEGIN and then ceding the write conn could
     leave an open transaction dangling
- Added backing functions to wrapper.rs
- Added decoder and tests
- Added tests for error types
- NOTE: Integration tests coming in a future PR

Author: pmorris-dev

Cargo.lock

@@ -23,6 +23,7 @@ futures-core = "0.3.31"
 time = "0.3.44"
 tokio = { version = "1.48.0", features = ["sync"] }
 indexmap = { version = "2.12.1", features = ["serde"] }
+base64 = "0.22.1"
 
 # SQLx for types and queries (time feature enables datetime type decoding)
 sqlx = { version = "0.8.6", features = ["sqlite", "json", "time", "runtime-tokio"] }

Cargo.toml

@@ -265,7 +265,6 @@ Common error codes include:
    * `INVALID_PATH` - Invalid database path
    * `IO_ERROR` - File system error
    * `MIGRATION_ERROR` - Migration failed
-   * `READ_ONLY_QUERY_IN_EXECUTE` - Attempted to use execute() for a read-only query
    * `MULTIPLE_ROWS_RETURNED` - `fetchOne()` query returned multiple rows
 
 ### Executing SELECT Queries
@@ -304,45 +303,35 @@ if (user) {
 
 ### Using Transactions
 
-Transactions ensure that multiple operations either all succeed or all fail together,
-maintaining data consistency:
+Execute multiple database operations atomically using `executeTransaction()`. All
+statements either succeed together or fail together, maintaining data consistency:
 
 ```typescript
-// Begin a transaction
-await db.beginTransaction();
-
-try {
-   // Execute multiple operations atomically
-   await db.execute(
-      'INSERT INTO users (name, email) VALUES ($1, $2)',
-      ['Alice', 'alice@example.com']
-   );
-
-   await db.execute(
-      'INSERT INTO audit_log (action, user) VALUES ($1, $2)',
-      ['user_created', 'Alice']
-   );
-
-   // Commit if all operations succeed
-   await db.commitTransaction();
-   console.log('Transaction completed successfully');
-
-} catch (error) {
-   // Rollback if any operation fails
-   await db.rollbackTransaction();
-   console.error('Transaction failed, rolled back:', error);
-   throw error;
-}
-```
-
-**Important Notes:**
-
-   * All operations between `beginTransaction()` and
-     `commitTransaction()`/`rollbackTransaction()` are executed as a single atomic unit
-   * If an error occurs, call `rollbackTransaction()` to discard all changes
-   * Nested transactions are not supported
-   * Always ensure transactions are either committed or rolled back to avoid locking
-     issues
+// Execute multiple inserts atomically
+const results = await db.executeTransaction([
+   ['INSERT INTO users (name, email) VALUES ($1, $2)', ['Alice', 'alice@example.com']],
+   ['INSERT INTO audit_log (action, user) VALUES ($1, $2)', ['user_created', 'Alice']]
+]);
+console.log(`User ID: ${results[0].lastInsertId}`);
+console.log(`Log rows affected: ${results[1].rowsAffected}`);
+
+// Bank transfer example - all operations succeed or all fail
+const results = await db.executeTransaction([
+   ['UPDATE accounts SET balance = balance - $1 WHERE id = $2', [100, 1]],
+   ['UPDATE accounts SET balance = balance + $1 WHERE id = $2', [100, 2]],
+   ['INSERT INTO transfers (from_id, to_id, amount) VALUES ($1, $2, $3)', [1, 2, 100]]
+]);
+console.log(`Transfer ID: ${results[2].lastInsertId}`);
+```
+
+**How it works:**
+
+   * Automatically executes `BEGIN` before running statements
+   * Executes all statements in order
+   * Commits with `COMMIT` if all statements succeed
+   * Rolls back with `ROLLBACK` if any statement fails
+   * The write connection is held for the entire transaction, ensuring atomicity
+   * Errors are thrown after rollback, preserving the original error message
 
 ### Closing Connections
 
@@ -465,8 +454,8 @@ const filtered = await db.fetchAll<User[]>(
 )
 ```
 
-> **Important:** Do NOT use `execute()` for read-only queries. It will return
-> an error. Always use `fetchAll()` or `fetchOne()` for reads.
+> **Note:** Use `execute()` and `executeTransaction()` for write operations.
+> For SELECT queries, use `fetchAll()` or `fetchOne()`.
 
 ## Configuration
 
@@ -541,7 +530,7 @@ await Database.closeAll()
 
 #### Instance Methods
 
-##### `execute(query: string, bindValues?: unknown[]): Promise<QueryResult>`
+##### `execute(query: string, bindValues?: unknown[]): Promise<WriteQueryResult>`
 
 Execute a write query (INSERT, UPDATE, DELETE, CREATE, etc.).
 
@@ -602,9 +591,9 @@ await db.remove()
 ### TypeScript Interfaces
 
 ```typescript
-interface QueryResult {
+interface WriteQueryResult {
    rowsAffected: number  // Number of rows modified
-   lastInsertId: number  // ROWID of last inserted row
+   lastInsertId: number  // ROWID of last inserted row (not set for WITHOUT ROWID tables, returns 0)
 }
 
 interface CustomConfig {

README.md

@@ -1,3 +1,4 @@
 fn main() {
+   // TODO: Add commands to the plugin
    tauri_plugin::Builder::new(&["hello"]).build();
 }

api-iife.js

@@ -12,10 +12,17 @@ import { invoke } from '@tauri-apps/api/core'
  */
 export type SqlValue = string | number | boolean | null | Uint8Array
 
-export interface QueryResult {
-   /** The number of rows affected by the query. */
+/**
+ * Result returned from write operations (INSERT, UPDATE, DELETE, etc.).
+ */
+export interface WriteQueryResult {
+   /** The number of rows affected by the write operation. */
    rowsAffected: number
-   /** The last inserted row ID (SQLite ROWID). */
+   /**
+    * The last inserted row ID (SQLite ROWID).
+    * Only set for INSERT operations on tables with a ROWID.
+    * Tables created with WITHOUT ROWID will not set this value (returns 0).
+    */
    lastInsertId: number
 }
 
@@ -107,11 +114,9 @@ export default class Database {
     * **execute**
     *
     * Executes a write query against the database (INSERT, UPDATE, DELETE, etc.).
-    * This method is specifically for mutations that modify data.
+    * This method is for mutations that modify data.
     *
-    * **Important:** Do NOT use this for SELECT queries. Use `fetchX()` instead.
-    * Using `execute()` for read queries will trigger an error to prevent unnecessary
-    * write mode initialization.
+    * For SELECT queries, use `fetchAll()` or `fetchOne()` instead.
     *
     * SQLite uses `$1`, `$2`, etc. for parameter binding.
     *
@@ -132,7 +137,7 @@ export default class Database {
     * );
     * ```
     */
-   async execute(query: string, bindValues?: SqlValue[]): Promise<QueryResult> {
+   async execute(query: string, bindValues?: SqlValue[]): Promise<WriteQueryResult> {
       const [rowsAffected, lastInsertId] = await invoke<[number, number]>(
          'plugin:sqlite|execute',
          {
@@ -147,6 +152,50 @@ export default class Database {
       }
    }
 
+   /**
+    * **executeTransaction**
+    *
+    * Executes multiple write statements atomically within a transaction.
+    * All statements either succeed together or fail together.
+    *
+    * The function automatically:
+    * - Begins a transaction (BEGIN)
+    * - Executes all statements in order
+    * - Commits on success (COMMIT)
+    * - Rolls back on any error (ROLLBACK)
+    *
+    * @param statements - Array of [query, values?] tuples to execute
+    * @returns Promise that resolves with results for each statement when all complete successfully
+    * @throws SqliteError if any statement fails (after rollback)
+    *
+    * @example
+    * ```ts
+    * // Execute multiple inserts atomically
+    * const results = await db.executeTransaction([
+    *    ['INSERT INTO users (name, email) VALUES ($1, $2)', ['Alice', 'alice@example.com']],
+    *    ['INSERT INTO audit_log (action, user) VALUES ($1, $2)', ['user_created', 'Alice']]
+    * ]);
+    * console.log(`User ID: ${results[0].lastInsertId}`);
+    * console.log(`Log rows affected: ${results[1].rowsAffected}`);
+    *
+    * // Mixed operations
+    * const results = await db.executeTransaction([
+    *    ['UPDATE accounts SET balance = balance - $1 WHERE id = $2', [100, 1]],
+    *    ['UPDATE accounts SET balance = balance + $1 WHERE id = $2', [100, 2]],
+    *    ['INSERT INTO transfers (from_id, to_id, amount) VALUES ($1, $2, $3)', [1, 2, 100]]
+    * ]);
+    * ```
+    */
+   async executeTransaction(statements: Array<[string, SqlValue[]?]>): Promise<WriteQueryResult[]> {
+      return await invoke<WriteQueryResult[]>('plugin:sqlite|execute_transaction', {
+         db: this.path,
+         statements: statements.map(([query, values]) => ({
+            query,
+            values: values ?? []
+         }))
+      })
+   }
+
    /**
     * **fetchAll**
     *
@@ -211,78 +260,6 @@ export default class Database {
       return result
    }
 
-   /**
-    * **beginTransaction**
-    *
-    * Begins a new database transaction. All subsequent operations will be
-    * part of this transaction until `commitTransaction()` or `rollbackTransaction()`
-    * is called.
-    *
-    * Transactions provide atomicity - either all operations succeed or all are rolled back.
-    *
-    * @example
-    * ```ts
-    * await db.beginTransaction();
-    * try {
-    *    await db.execute('INSERT INTO users (name) VALUES ($1)', ['Alice']);
-    *    await db.execute('INSERT INTO logs (action) VALUES ($1)', ['user_created']);
-    *    await db.commitTransaction();
-    * } catch (error) {
-    *    await db.rollbackTransaction();
-    *    throw error;
-    * }
-    * ```
-    */
-   async beginTransaction(): Promise<void> {
-      await invoke('plugin:sqlite|begin_transaction', {
-         db: this.path
-      })
-   }
-
-   /**
-    * **commitTransaction**
-    *
-    * Commits the current transaction, making all changes permanent.
-    *
-    * @example
-    * ```ts
-    * await db.beginTransaction();
-    * await db.execute('INSERT INTO users (name) VALUES ($1)', ['Alice']);
-    * await db.execute('INSERT INTO logs (action) VALUES ($1)', ['user_created']);
-    * await db.commitTransaction();
-    * ```
-    */
-   async commitTransaction(): Promise<void> {
-      await invoke('plugin:sqlite|commit_transaction', {
-         db: this.path
-      })
-   }
-
-   /**
-    * **rollbackTransaction**
-    *
-    * Rolls back the current transaction, discarding all changes made since
-    * `beginTransaction()` was called.
-    *
-    * @example
-    * ```ts
-    * await db.beginTransaction();
-    * try {
-    *    await db.execute('INSERT INTO users (name) VALUES ($1)', ['Alice']);
-    *    await db.execute('INSERT INTO logs (action) VALUES ($1)', ['user_created']);
-    *    await db.commitTransaction();
-    * } catch (error) {
-    *    await db.rollbackTransaction();
-    *    throw error;
-    * }
-    * ```
-    */
-   async rollbackTransaction(): Promise<void> {
-      await invoke('plugin:sqlite|rollback_transaction', {
-         db: this.path
-      })
-   }
-
    /**
     * **close**
     *