Type Alias UniqueItems<Value>

UniqueItems: tags.TagBase<
    {
        exclusive: true;
        kind: "uniqueItems";
        schema: { uniqueItems: true };
        target: "array";
        validate: Value extends true
            ? "$importInternal(\"isUniqueItems\")($input)"
            : undefined;
        value: Value;
    },
>

Array unique elements constraint.

UniqueItems is a type tag that validates all elements in an array are unique (no duplicates). Apply it to array properties using TypeScript intersection types.

Uniqueness is determined by:

Primitives: Strict equality (===)
Objects: Deep structural comparison

This constraint is commonly combined with MinItems and MaxItems for comprehensive array validation. It's useful for modeling set-like data that must be represented as arrays in JSON.

The constraint is enforced at runtime by typia.is(), typia.assert(), and typia.validate(). It generates uniqueItems: true in JSON Schema.

Type Parameters

Value extends boolean = true
Boolean flag, defaults to true (enable constraint)

Author

Jeongho Nam - https://github.com/samchon

Example

interface Preferences {
    // No duplicate tags allowed
    tags: (string & UniqueItems)[];
    // Unique user IDs
    favoriteUserIds: (number & UniqueItems)[];
  }

Type Alias UniqueItems<Value>

Type Parameters

Author

Example

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