Common Patterns

Discriminated unions


const eventSchema = new SchemaBuilder()
  .object()
  .properties({ type: (s) => s.string() })
  .required(["type"])
  .oneOf(
    (s) =>
      s.object().properties({
        type: (s) => s.const("click"),
        x: (s) => s.number(),
        y: (s) => s.number(),
      }),
    (s) =>
      s.object().properties({
        type: (s) => s.const("scroll"),
        scrollY: (s) => s.number(),
      }),
  )
  .build();

Pagination

A reusable factory that wraps any item schema.


const paginatedSchema = (itemSchema: (s: SchemaBuilder) => SchemaBuilder) =>
  new SchemaBuilder()
    .object()
    .properties({
      items: (s) => s.array().items(itemSchema),
      total: (s) => s.integer().minimum(0),
      page: (s) => s.integer().minimum(1),
      pageSize: (s) => s.integer().minimum(1).maximum(100),
    })
    .required(["items", "total", "page", "pageSize"])
    .build();

Polymorphic IDs


const idSchema = new SchemaBuilder()
  .anyOf(
    (s) => s.string().pattern("^[0-9a-f]{24}$"), // MongoDB ObjectId
    (s) => s.string().format("uuid"), // UUID
    (s) => s.integer().minimum(1), // integer ID
  )
  .build();