added unique constraint assertion tools

pkg/unique.ts

@@ -0,0 +1,22 @@
+import { z } from "zod";
+
+export type AssertUniqueType<T extends Record<string, unknown>> = z.ZodEffects<z.ZodArray<z.ZodType<T>>, T[], unknown>;
+
+export function generateUniqueValidator<T extends Record<string, unknown>>(validator: z.ZodType<T>, ...keys: (keyof T)[]) {
+    return validator.array().refine((val) => {
+        for (const key of keys ?? []) {
+            const values = val.map((item) => item[key as keyof T]);
+            return values.length === new Set(values).size;
+        }
+    }, {
+        message: "Encountered duplicate values in unique field"
+    }) satisfies AssertUniqueType<T>;
+}
+
+export function assertUniqueKeys<T extends Record<string, unknown>>(data: T[], validator: z.ZodType<T>, ...keys: (keyof T)[]) {
+    return generateUniqueValidator(validator, ...keys).parse(data) satisfies T[];
+}
+
+export async function assertUniqueKeysAsync<T extends Record<string, unknown>>(data: T[], validator: z.ZodType<T>, ...keys: (keyof T)[]) {
+    return generateUniqueValidator(validator, ...keys).parseAsync(data) satisfies Promise<T[]>;
+}