We’re still putting a lot of trust in our database layer as well. We should make sure that it’s also giving us back what we think it is.

There are a number of ways to go about this, but we might start with a simple abstraction.

class TaskClient {
	private database: Database;

	constructor(database: Database) {
		this.database = database;
	}

	async getTasks({ completed }: { completed: boolean }) {
		const query = completed
			? await this.database.prepare('SELECT * FROM tasks WHERE completed = 1')
			: await this.database.prepare('SELECT * FROM tasks WHERE completed = 0');

		return TasksSchema.parse(await query.all());
	}

	async getTask(id: number) {
		const query = await this.database.prepare('SELECT * FROM tasks WHERE id = ?');
		return TaskSchema.or(z.undefined()).parse(await query.get([id]));
	}

	async createTask({ task }: { task: NewTask }) {
		const query = await this.database.prepare(
			'INSERT INTO tasks (title, description) VALUES (?, ?)',
		);
		await query.run([task.title, task.description]);
	}

	async updateTask(id: number, task: NewTask) {
		const previous = TaskSchema.parse(await this.getTask(id));
		const updated = { ...previous, ...task };

		const query = await this.database.prepare(
			`UPDATE tasks SET title = ?, description = ?, completed = ? WHERE id = ?`,
		);

		await query.run([updated.title, updated.description, updated.completed, id]);
	}

	async deleteTask(id: number) {
		const query = await this.database.prepare('DELETE FROM tasks WHERE id = ?');
		await query.run([id]);
	}
}

Adding Our Task Model to Our API Layer