feat: schema refiner

.changeset/ten-poems-appear.md

@@ -0,0 +1,5 @@
+---
+"openapi-zod-client": minor
+---
+
+Add `schemaRefiner` option to allow refining the OpenAPI schema before its converted to a Zod schema

lib/src/openApiToZod.ts

@@ -20,10 +20,12 @@ type ConversionArgs = {
  * @see https://github.com/colinhacks/zod
  */
 // eslint-disable-next-line sonarjs/cognitive-complexity
-export function getZodSchema({ schema, ctx, meta: inheritedMeta, options }: ConversionArgs): CodeMeta {
-    if (!schema) {
+export function getZodSchema({ schema: $schema, ctx, meta: inheritedMeta, options }: ConversionArgs): CodeMeta {
+    if (!$schema) {
         throw new Error("Schema is required");
     }
+
+    const schema = options?.schemaRefiner?.($schema, inheritedMeta) ?? $schema;
     const code = new CodeMeta(schema, ctx, inheritedMeta);
     const meta = {
         parent: code.inherit(inheritedMeta?.parent),

lib/src/template-context.ts

@@ -1,4 +1,4 @@
-import type { OpenAPIObject, OperationObject, PathItemObject, SchemaObject } from "openapi3-ts";
+import type { OpenAPIObject, OperationObject, PathItemObject, ReferenceObject, SchemaObject } from "openapi3-ts";
 import { sortBy, sortListFromRefArray, sortObjKeysFromArray } from "pastable/server";
 import { ts } from "tanu";
 import { match } from "ts-pattern";
@@ -11,6 +11,7 @@ import { getTypescriptFromOpenApi } from "./openApiToTypescript";
 import { getZodSchema } from "./openApiToZod";
 import { topologicalSort } from "./topologicalSort";
 import { asComponentSchema, normalizeString } from "./utils";
+import type { CodeMetaData } from "./CodeMeta";
 
 const file = ts.createSourceFile("", "", ts.ScriptTarget.ESNext, true);
 const printer = ts.createPrinter({ newLine: ts.NewLineKind.LineFeed });
@@ -403,4 +404,9 @@ export type TemplateContextOptions = {
      * If 2 schemas have the same name but different types, export subsequent names with numbers appended
      */
     exportAllNamedSchemas?: boolean;
+
+    /**
+     * A function that runs in the schema conversion process to refine the schema before it's converted to a Zod schema.
+     */
+    schemaRefiner?: <T extends SchemaObject | ReferenceObject>(schema: T, parentMeta?: CodeMetaData) => T;
 };

lib/tests/schema-refiner.test.ts

@@ -0,0 +1,41 @@
+import { isReferenceObject } from "openapi3-ts";
+import { getZodSchema } from "../src/openApiToZod";
+import { test, expect } from "vitest";
+
+test("schema-refiner", () => {
+    expect(
+        getZodSchema({
+            schema: {
+                properties: {
+                    name: {
+                        type: "string",
+                    },
+                    email: {
+                        type: "string",
+                    },
+                },
+            },
+            options: {
+                schemaRefiner(schema) {
+                    if (isReferenceObject(schema) || !schema.properties) {
+                        return schema;
+                    }
+
+                    if (!schema.required && schema.properties) {
+                        for (const key in schema.properties) {
+                            const prop = schema.properties[key];
+
+                            if (!isReferenceObject(prop)) {
+                                prop.nullable = true;
+                            }
+                        }
+                    }
+
+                    return schema;
+                },
+            },
+        })
+    ).toMatchInlineSnapshot(
+        '"z.object({ name: z.string().nullable(), email: z.string().nullable() }).partial().passthrough()"'
+    );
+});