acacode · J3MPA · Aug 5, 2025 · Aug 5, 2025 · Aug 5, 2025
diff --git a/.changeset/real-wombats-dream.md b/.changeset/real-wombats-dream.md
@@ -0,0 +1,5 @@
+---
+"swagger-typescript-api": minor
+---
+
+Supports immutable types with --make-immutable or makeImmutable
diff --git a/index.ts b/index.ts
@@ -86,6 +86,11 @@ const generateCommand = defineCommand({
       description: "generate readonly properties",
       default: codeGenBaseConfig.addReadonly,
     },
+    "make-immutable": {
+      type: "boolean",
+      description: "makes all properties and values readonly",
+      default: codeGenBaseConfig.makeImmutable,
+    },
     "another-array-type": {
       type: "boolean",
       description: "generate array types as Array<Type> (by default Type[])",

diff --git a/src/configuration.ts b/src/configuration.ts
@@ -30,6 +30,8 @@ const TsKeyword = {
   Enum: "enum",
   Interface: "interface",
   Array: "Array",
+  ReadonlyArray: "ReadonlyArray",
+  Readonly: "Readonly",
   Record: "Record",
   Intersection: "&",
   Union: "|",
@@ -55,6 +57,8 @@ export class CodeGenConfig {
   generateUnionEnums = false;
   /** CLI flag */
   addReadonly = false;
+  /** CLI flag */
+  makeImmutable = false;
   enumNamesAsValues = false;
   /** parsed swagger schema from getSwaggerObject() */
 
@@ -225,12 +229,20 @@ export class CodeGenConfig {
     /**
      * $A[] or Array<$A>
      */
-    ArrayType: (content: unknown) => {
+    ArrayType: ({ readonly, content }: Record<string, unknown>) => {
       if (this.anotherArrayType) {
-        return this.Ts.TypeWithGeneric(this.Ts.Keyword.Array, [content]);
+        return this.Ts.TypeWithGeneric(
+          readonly ? this.Ts.Keyword.ReadonlyArray : this.Ts.Keyword.Array,
+          [content],
+        );
       }
-
-      return `${this.Ts.ExpressionGroup(content)}[]`;
+      return lodash
+        .compact([
+          readonly && "readonly ",
+          this.Ts.ExpressionGroup(content),
+          "[]",
+        ])
+        .join("");
     },
     /**
      * "$A"
@@ -265,8 +277,16 @@ export class CodeGenConfig {
     /**
      * Record<$A1, $A2>
      */
-    RecordType: (key: unknown, value: unknown) =>
-      this.Ts.TypeWithGeneric(this.Ts.Keyword.Record, [key, value]),
+    RecordType: ({ readonly, key, value }: Record<string, unknown>) => {
+      const record = this.Ts.TypeWithGeneric(this.Ts.Keyword.Record, [
+        key,
+        value,
+      ]);
+      if (readonly) {
+        return this.Ts.TypeWithGeneric(this.Ts.Keyword.Readonly, [record]);
+      }
+      return record;
+    },
     /**
      * readonly $key?:$value
      */
@@ -277,8 +297,14 @@ export class CodeGenConfig {
     /**
      * [key: $A1]: $A2
      */
-    InterfaceDynamicField: (key: unknown, value: unknown) =>
-      `[key: ${key}]: ${value}`,
+    InterfaceDynamicField: ({
+      readonly,
+      key,
+      value,
+    }: Record<string, unknown>) =>
+      lodash
+        .compact([readonly && "readonly ", `[key: ${key}]`, `: ${value}`])
+        .join(""),
 
     /**
      * EnumName.EnumKey
@@ -344,8 +370,11 @@ export class CodeGenConfig {
     /**
      * [$A1, $A2, ...$AN]
      */
-    Tuple: (values: unknown[]) => {
-      return `[${values.join(", ")}]`;
+    Tuple: ({
+      readonly,
+      values,
+    }: Record<string, unknown> & { values: unknown[] }) => {
+      return `${readonly ? "readonly " : ""}[${values.join(", ")}]`;
     },
   };
 

diff --git a/src/schema-parser/base-schema-parsers/array.ts b/src/schema-parser/base-schema-parsers/array.ts
@@ -4,7 +4,10 @@ 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, readOnly } = this.schema || {};
+
+    const readonly =
+      (readOnly && this.config.addReadonly) || this.config.makeImmutable;
 
     if (Array.isArray(items) && type === SCHEMA_TYPES.ARRAY) {
       const tupleContent = [];
@@ -15,12 +18,15 @@ export class ArraySchemaParser extends MonoSchemaParser {
             .getInlineParseContent(),
         );
       }
-      contentType = this.config.Ts.Tuple(tupleContent);
+      contentType = this.config.Ts.Tuple({
+        readonly,
+        values: tupleContent,
+      });
     } else {
       const content = this.schemaParserFabric
         .createSchemaParser({ schema: items, schemaPath: this.schemaPath })
         .getInlineParseContent();
-      contentType = this.config.Ts.ArrayType(content);
+      contentType = this.config.Ts.ArrayType({ readonly, content });
     }
 
     return {

diff --git a/src/schema-parser/base-schema-parsers/discriminator.ts b/src/schema-parser/base-schema-parsers/discriminator.ts
@@ -58,7 +58,7 @@ export class DiscriminatorSchemaParser extends MonoSchemaParser {
       "schemas",
       this.typeName,
     ]);
-    const { discriminator } = this.schema;
+    const { discriminator, readOnly } = this.schema;
     const mappingEntries = lodash.entries(discriminator.mapping);
     const ableToCreateMappingType =
       !skipMappingType &&
@@ -84,6 +84,9 @@ export class DiscriminatorSchemaParser extends MonoSchemaParser {
       const content = ts.IntersectionType([
         ts.ObjectWrapper(
           ts.TypeField({
+            readonly:
+              (readOnly && this.config.addReadonly) ||
+              this.config.makeImmutable,
             key: ts.StringValue(discriminator.propertyName),
             value: "Key",
           }),
@@ -127,6 +130,9 @@ export class DiscriminatorSchemaParser extends MonoSchemaParser {
         ts.IntersectionType([
           ts.ObjectWrapper(
             ts.TypeField({
+              readonly:
+                (mappingSchema.readOnly && this.config.addReadonly) ||
+                this.config.makeImmutable,
               key: discriminator.propertyName,
               value: mappingUsageKey,
             }),

diff --git a/src/schema-parser/base-schema-parsers/object.ts b/src/schema-parser/base-schema-parsers/object.ts
@@ -73,7 +73,8 @@ export class ObjectSchemaParser extends MonoSchemaParser {
         name: fieldName,
         value: fieldValue,
         field: this.config.Ts.TypeField({
-          readonly: readOnly && this.config.addReadonly,
+          readonly:
+            (readOnly && this.config.addReadonly) || this.config.makeImmutable,
           optional: !required,
           key: fieldName,
           value: fieldValue,
@@ -101,10 +102,13 @@ export class ObjectSchemaParser extends MonoSchemaParser {
         $$raw: { additionalProperties },
         description: "",
         isRequired: false,
-        field: this.config.Ts.InterfaceDynamicField(
-          interfaceKeysContent,
-          this.config.Ts.Keyword.Any,
-        ),
+        field: this.config.Ts.InterfaceDynamicField({
+          readonly:
+            (additionalProperties.readOnly && this.config.addReadonly) ||
+            this.config.makeImmutable,
+          key: interfaceKeysContent,
+          value: this.config.Ts.Keyword.Any,
+        }),
       });
     }
 

diff --git a/src/schema-parser/base-schema-parsers/primitive.ts b/src/schema-parser/base-schema-parsers/primitive.ts
@@ -4,9 +4,12 @@ import { MonoSchemaParser } from "../mono-schema-parser.js";
 export class PrimitiveSchemaParser extends MonoSchemaParser {
   override parse() {
     let contentType = null;
-    const { additionalProperties, type, description, items } =
+    const { additionalProperties, type, description, items, readOnly } =
       this.schema || {};
 
+    const readonly =
+      (readOnly && this.config.addReadonly) || this.config.makeImmutable;
+
     if (type === this.config.Ts.Keyword.Object && additionalProperties) {
       const propertyNamesSchema = this.schemaUtils.getSchemaPropertyNamesSchema(
         this.schema,
@@ -37,10 +40,11 @@ export class PrimitiveSchemaParser extends MonoSchemaParser {
         recordValuesContent = this.config.Ts.Keyword.Any;
       }
 
-      contentType = this.config.Ts.RecordType(
-        recordKeysContent,
-        recordValuesContent,
-      );
+      contentType = this.config.Ts.RecordType({
+        readonly,
+        key: recordKeysContent,
+        value: recordValuesContent,
+      });
     }
 
     if (Array.isArray(type) && type.length) {
@@ -51,13 +55,14 @@ export class PrimitiveSchemaParser extends MonoSchemaParser {
     }
 
     if (Array.isArray(items) && type === SCHEMA_TYPES.ARRAY) {
-      contentType = this.config.Ts.Tuple(
-        items.map((item) =>
+      contentType = this.config.Ts.Tuple({
+        readonly,
+        values: items.map((item) =>
           this.schemaParserFabric
             .createSchemaParser({ schema: item, schemaPath: this.schemaPath })
             .getInlineParseContent(),
         ),
-      );
+      });
     }
 
     return {

diff --git a/src/schema-parser/schema-formatters.ts b/src/schema-parser/schema-formatters.ts
@@ -82,10 +82,13 @@ export class SchemaFormatters {
             ? this.config.Ts.ObjectWrapper(
                 this.formatObjectContent(parsedSchema.content),
               )
-            : this.config.Ts.RecordType(
-                this.config.Ts.Keyword.String,
-                this.config.Ts.Keyword.Any,
-              ),
+            : this.config.Ts.RecordType({
+                readonly:
+                  (parsedSchema.readOnly && this.config.addReadonly) ||
+                  this.config.makeImmutable,
+                key: this.config.Ts.Keyword.String,
+                value: this.config.Ts.Keyword.Any,
+              }),
         ),
       };
     },

diff --git a/tests/spec/readonly-always/__snapshots__/basic.test.ts.snap b/tests/spec/readonly-always/__snapshots__/basic.test.ts.snap
@@ -0,0 +1,51 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`basic > immutable 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 ##
+ * ---------------------------------------------------------------
+ */
+
+export interface Pet {
+  /** @format int64 */
+  readonly id: number;
+  readonly name: string;
+  readonly tag?: string;
+  readonly list?: readonly string[];
+  readonly obj?: Readonly<Record<string, any>>;
+  readonly multiple?: string | number;
+}
+"
+`;
+
+exports[`basic > immutable another-array-type 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 ##
+ * ---------------------------------------------------------------
+ */
+
+export interface Pet {
+  /** @format int64 */
+  readonly id: number;
+  readonly name: string;
+  readonly tag?: string;
+  readonly list?: ReadonlyArray<string>;
+  readonly obj?: Readonly<Record<string, any>>;
+  readonly multiple?: string | number;
+}
+"
+`;
diff --git a/tests/spec/readonly-always/basic.test.ts b/tests/spec/readonly-always/basic.test.ts
@@ -0,0 +1,51 @@
+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("immutable", async () => {
+    await generateApi({
+      fileName: "schema",
+      input: path.resolve(import.meta.dirname, "schema.json"),
+      output: tmpdir,
+      silent: true,
+      makeImmutable: true,
+      generateClient: false,
+    });
+
+    const content = await fs.readFile(path.join(tmpdir, "schema.ts"), {
+      encoding: "utf8",
+    });
+
+    expect(content).toMatchSnapshot();
+  });
+  test("immutable another-array-type", async () => {
+    await generateApi({
+      fileName: "schema",
+      input: path.resolve(import.meta.dirname, "schema.json"),
+      output: tmpdir,
+      silent: true,
+      makeImmutable: true,
+      generateClient: false,
+      anotherArrayType: true,
+    });
+
+    const content = await fs.readFile(path.join(tmpdir, "schema.ts"), {
+      encoding: "utf8",
+    });
+
+    expect(content).toMatchSnapshot();
+  });
+});