Supports minItems / maxItems

README.md

@@ -159,6 +159,7 @@ npx openapi-typescript schema.yaml
 | `--default-non-nullable`       |       | `false`  | (optional) Treat schema objects with default values as non-nullable                                                                     |
 | `--prettier-config [location]` | `-c`  |          | (optional) Path to your custom Prettier configuration for output                                                                        |
 | `--export-type`                |       | `false`  | (optional) Export `type` instead of `interface`                                                                                         |
+| `--support-array-length`       |       | `false`  | (optional) Generate tuples using array minItems / maxItems                                                                              |
 | `--raw-schema`                 |       | `false`  | Generate TS types from partial schema (e.g. having `components.schema` at the top level)                                                |
 | `--version`                    |       |          | Force OpenAPI version with `--version 3` or `--version 2` (required for `--raw-schema` when version is unknown)                         |
 

bin/cli.js

@@ -26,6 +26,7 @@ Options
   --prettier-config, -c        (optional) specify path to Prettier config file
   --raw-schema                 (optional) Parse as partial schema (raw components)
   --export-type                (optional) Export type instead of interface
+  --support-array-length       (optional) Generate tuples using array minItems / maxItems
   --version                    (optional) Force schema parsing version
 `;
 
@@ -42,7 +43,7 @@ function errorAndExit(errorMessage) {
 const [, , input, ...args] = process.argv;
 const flags = parser(args, {
   array: ["header"],
-  boolean: ["defaultNonNullable", "immutableTypes", "rawSchema", "exportType"],
+  boolean: ["defaultNonNullable", "immutableTypes", "rawSchema", "exportType", "supportArrayLength"],
   number: ["version"],
   string: ["auth", "header", "headersObject", "httpMethod", "prettierConfig"],
   alias: {
@@ -92,6 +93,7 @@ async function generateSchema(pathToSpec) {
     httpHeaders,
     httpMethod: flags.httpMethod,
     exportType: flags.exportType,
+    supportArrayLength: flags.supportArrayLength,
   });
 
   // output

src/index.ts

@@ -41,6 +41,7 @@ async function openapiTS(
     immutableTypes: options.immutableTypes || false,
     rawSchema: options.rawSchema || false,
     version: options.version || 3,
+    supportArrayLength: options.supportArrayLength,
   } as any;
 
   // note: we may be loading many large schemas into memory at once; take care to reuse references without cloning

src/transform/schema.ts

@@ -189,7 +189,31 @@ export function transformSchemaObj(node: any, options: TransformSchemaObjOptions
         if (Array.isArray(node.items)) {
           output += `${readonly}${tsTupleOf(node.items.map((node: any) => transformSchemaObj(node, options)))}`;
         } else {
-          output += `${readonly}${tsArrayOf(node.items ? transformSchemaObj(node.items as any, options) : "unknown")}`;
+          const minItems: number = Number.isInteger(node.minItems) && node.minItems >= 0 ? node.minItems : 0;
+          const maxItems: number | undefined =
+            Number.isInteger(node.maxItems) && node.maxItems >= 0 && minItems <= node.maxItems
+              ? node.maxItems
+              : undefined;
+
+          const estimateCodeSize =
+            maxItems === undefined ? minItems : (maxItems * (maxItems + 1) - minItems * (minItems - 1)) / 2;
+          const items = node.items ? transformSchemaObj(node.items as any, options) : "unknown";
+          if ((minItems !== 0 || maxItems !== undefined) && options.supportArrayLength && estimateCodeSize < 30) {
+            if (maxItems === undefined) {
+              output += `${readonly}${tsTupleOf([
+                ...Array.from({ length: minItems }).map(() => items),
+                `...${tsArrayOf(items)}`,
+              ])}`;
+            } else {
+              output += tsUnionOf(
+                Array.from({ length: maxItems - minItems + 1 })
+                  .map((_, i) => i + minItems)
+                  .map((n) => `${readonly}${tsTupleOf(Array.from({ length: n }).map(() => items))}`)
+              );
+            }
+          } else {
+            output += `${readonly}${tsArrayOf(items)}`;
+          }
         }
         break;
       }

src/types.ts

@@ -155,6 +155,10 @@ export interface SwaggerToTSOptions {
    * (optional) Export type instead of interface
    */
   exportType?: boolean;
+  /**
+   * (optional) Generate tuples using array minItems / maxItems
+   */
+  supportArrayLength?: boolean;
 }
 
 /** Context passed to all submodules */
@@ -169,4 +173,5 @@ export interface GlobalContext {
   namespace?: string;
   rawSchema: boolean;
   version: number;
+  supportArrayLength?: boolean;
 }

test/core/schema.test.js

@@ -11,6 +11,7 @@ const defaults = {
   required: new Set(),
   rawSchema: false,
   version: 3,
+  supportArrayLength: false,
 };
 
 describe("SchemaObject", () => {
@@ -150,6 +151,34 @@ describe("SchemaObject", () => {
       );
     });
 
+    it("array (supportArrayLength)", () => {
+      // (same as above test, but with supportArrayLength: true)
+      const opts = { ...defaults, supportArrayLength: true };
+      expect(transform({ type: "array", items: { type: "string" } }, opts)).to.equal(`(string)[]`);
+      expect(transform({ type: "array", items: { type: "string" }, minItems: 1 }, opts)).to.equal(
+        `[string, ...(string)[]]`
+      );
+      expect(transform({ type: "array", items: { type: "string" }, maxItems: 2 }, opts)).to.equal(
+        `([]) | ([string]) | ([string, string])`
+      );
+      expect(transform({ type: "array", items: { type: "string" }, maxItems: 20 }, opts)).to.equal(`(string)[]`);
+    });
+
+    it("array (immutableTypes, supportArrayLength)", () => {
+      // (same as above test, but with immutableTypes: true, supportArrayLength: true)
+      const opts = { ...defaults, immutableTypes: true, supportArrayLength: true };
+      expect(transform({ type: "array", items: { type: "string" } }, opts)).to.equal(`readonly (string)[]`);
+      expect(transform({ type: "array", items: { type: "string" }, minItems: 1 }, opts)).to.equal(
+        `readonly [string, ...(string)[]]`
+      );
+      expect(transform({ type: "array", items: { type: "string" }, maxItems: 2 }, opts)).to.equal(
+        `(readonly []) | (readonly [string]) | (readonly [string, string])`
+      );
+      expect(transform({ type: "array", items: { type: "string" }, maxItems: 20 }, opts)).to.equal(
+        `readonly (string)[]`
+      );
+    });
+
     it("enum", () => {
       const enumBasic = ["Totoro", "Sats'uki", "Mei"]; // note: also tests quotes in enum
       expect(

test/v3/expected/consts-enums.support-array-length.ts

@@ -0,0 +1,35 @@
+/**
+ * This file was auto-generated by openapi-typescript.
+ * Do not make direct changes to the file.
+ */
+
+export interface paths {
+  "/test": {
+    get: {
+      responses: {
+        /** A list of types. */
+        200: unknown;
+      };
+    };
+  };
+}
+
+export interface components {
+  schemas: {
+    /** @description Enum with null and nullable */
+    MyType: {
+      /** @enum {string|null} */
+      myEnumTestFieldNullable?: ("foo" | "bar" | null) | null;
+      /** @enum {string|null} */
+      myEnumTestField?: ("foo" | "bar" | null) | null;
+      /** @constant */
+      myConstTestField?: "constant-value";
+      /** @constant */
+      myConstTestFieldNullable?: 4 | null;
+    };
+  };
+}
+
+export interface operations {}
+
+export interface external {}