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feat: Add support for prefixItems tuple generation #1813

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Merged
js2me merged 4 commits into from
Jul 17, 2026
Merged

feat: Add support for prefixItems tuple generation #1813

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368e71c
update array.ts to interprit prefixItem arrays
freddie-volant Jul 16, 2026
c84f0c3
Add changeset patch
freddie-volant Jul 16, 2026
49a67ac
Add spec test + snapshot for prefixItems array
freddie-volant Jul 17, 2026
b1f519f
Add newline at end of schema.yaml
freddie-volant Jul 17, 2026
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5 changes: 5 additions & 0 deletions .changeset/dark-toes-live.md
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---
"swagger-typescript-api": patch
---

Add support for generating tuple types from prefixItems array schemas
12 changes: 9 additions & 3 deletions src/schema-parser/base-schema-parsers/array.ts
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Expand Up @@ -4,11 +4,17 @@ import { MonoSchemaParser } from "../mono-schema-parser.js";
export class ArraySchemaParser extends MonoSchemaParser {
override parse() {
let contentType;
const { type, description, items } = this.schema || {};
const { type, description, items, prefixItems } = this.schema || {};

if (Array.isArray(items) && type === SCHEMA_TYPES.ARRAY) {
const tupleItems = Array.isArray(prefixItems)
? prefixItems
: Array.isArray(items)
? items
: null;

if (tupleItems && type === SCHEMA_TYPES.ARRAY) {

@cubic-dev-ai cubic-dev-ai Bot Jul 16, 2026

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P2: When prefixItems is combined with items (or omitted, implying an open tuple), the generated type is always a fixed-length closed tuple [A, B, C], ignoring the items schema that should describe trailing/rest elements (e.g. [A, B, ...string[]]) or the fact that extra items of any type are allowed by default. Consider appending a rest element derived from items when it's present alongside prefixItems.

Prompt for AI agents 
Check if this issue is valid — if so, understand the root cause and fix it. At src/schema-parser/base-schema-parsers/array.ts, line 15:

<comment>When `prefixItems` is combined with `items` (or omitted, implying an open tuple), the generated type is always a fixed-length closed tuple `[A, B, C]`, ignoring the `items` schema that should describe trailing/rest elements (e.g. `[A, B, ...string[]]`) or the fact that extra items of any type are allowed by default. Consider appending a rest element derived from `items` when it's present alongside `prefixItems`.</comment>

<file context>
@@ -4,11 +4,17 @@ import { MonoSchemaParser } from "../mono-schema-parser.js";
+        ? items
+        : null;
+
+    if (tupleItems && type === SCHEMA_TYPES.ARRAY) {
       const tupleContent = [];
-      for (const item of items) {
</file context>

const tupleContent = [];
for (const item of items) {
for (const item of tupleItems) {
tupleContent.push(
this.schemaParserFabric
.createSchemaParser({ schema: item, schemaPath: this.schemaPath })
Expand Down
22 changes: 22 additions & 0 deletions tests/spec/prefixItems-array/__snapshots__/basic.test.ts.snap
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// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html

exports[`basic > prefixItems-array 1`] = `
"/* eslint-disable */
/* tslint:disable */
// @ts-nocheck
/*
* ---------------------------------------------------------------
* ## THIS FILE WAS GENERATED VIA SWAGGER-TYPESCRIPT-API ##
* ## ##
* ## AUTHOR: acacode ##
* ## SOURCE: https://github.com/acacode/swagger-typescript-api ##
* ---------------------------------------------------------------
*/

/**
* @maxItems 3
* @minItems 3
*/
export type PrefixItemsArrayType = [number, boolean, string];
"
`;
34 changes: 34 additions & 0 deletions tests/spec/prefixItems-array/basic.test.ts
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import * as fs from "node:fs/promises";
import * as os from "node:os";
import * as path from "node:path";
import { afterAll, beforeAll, describe, expect, test } from "vitest";
import { generateApi } from "../../../src/index.js";

describe("basic", async () => {
let tmpdir = "";

beforeAll(async () => {
tmpdir = await fs.mkdtemp(path.join(os.tmpdir(), "swagger-typescript-api"));
});

afterAll(async () => {
await fs.rm(tmpdir, { recursive: true });
});

test("prefixItems-array", async () => {
await generateApi({
fileName: "schema",
input: path.resolve(import.meta.dirname, "schema.yaml"),
output: tmpdir,
silent: true,
anotherArrayType: true,
generateClient: false,
});

const content = await fs.readFile(path.join(tmpdir, "schema.ts"), {
encoding: "utf8",
});

expect(content).toMatchSnapshot();
});
});
14 changes: 14 additions & 0 deletions tests/spec/prefixItems-array/schema.yaml
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openapi: 3.1.0
info:
title: test
version: 0.0.0
components:
schemas:
PrefixItemsArrayType:
type: array
prefixItems:
- type: number
- type: boolean
- type: string
maxItems: 3
minItems: 3