รูปแบบที่นำกลับมาใช้ใหม่สำหรับโมเดลข้อมูล

บทนำ

ชนิดแบ่งหน้า<T>

type Paginated<T> = {
  items: T[];
  total: number;
  page: number;
  pageSize: number;
};

type User = { id: number; name: string };

const page1: Paginated<User> = {
  items: [{ id: 1, name: "Ada" }],
  total: 10,
  page: 1,
  pageSize: 5,
};

console.log(page1.items[0].name);

ชนิดผลลัพธ์<T,E>

type Ok<T> = { ok: true; data: T };
type Err<E = string> = { ok: false; error: E };

type Result<T, E = string> = Ok<T> | Err<E>;

function readUser(id: number): Result<{ id: number; name: string }> {
  return id > 0 ? { ok: true, data: { id, name: "Ada" } } : { ok: false, error: "not found" };
}

const r = readUser(1);
if (r.ok) {
  console.log(r.data.name);
} else {
  console.error(r.error);
}

รูปแบบออบเจ็กต์ถ่ายโอนข้อมูล

type User = { id: number; name: string; email?: string; role: "user" | "admin" };

type UserCreateDto = Pick<User, "name" | "email">; // fields required to create

// Update = partial editable fields
type UserUpdateDto = Partial<Pick<User, "name" | "email">>;

const createBody: UserCreateDto = { name: "Ada", email: "a@x.io" };
const updateBody: UserUpdateDto = { name: "Ada L." };

MapById<T>

type Key = string | number;

type MapById<T extends { id: Key }> = Record<Key, T>;

const byId: MapById<{ id: number; name: string }> = {
  1: { id: 1, name: "Ada" },
  2: { id: 2, name: "Lin" },
};

console.log(byId[1].name);

เคล็ดลับ

ตรวจสอบชนิดแบ่งหน้า<T>

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