fix(json-schema): handle duplicate field names (#13)

Some app configs may have duplicate field names. Forman handles that
with bidirectional value binding. In JSON Schema, we can't have
duplicate property names, so if the property has already been defined,
we skip the redefinition, and keep the first defined one only.

Author: dominikkadera

.gitignore

@@ -1,6 +1,7 @@
 # system related
 .DS_Store
 .vscode
+.idea
 
 #test related
 coverage/*

src/forman.ts

@@ -221,6 +221,15 @@ function handleCollectionType(field: FormanSchemaField, result: JSONSchema7, con
 
         if (!subField.name) return;
 
+        /*
+        Some app configs may have duplicate field names.
+        Forman handles that with bidirectional value binding.
+        In JSON Schema, we can't have duplicate property names,
+        so if the property has already been defined, we skip the redefinition,
+        and keep the first defined one only.
+         */
+        if (result.properties && Object.hasOwn(result.properties, subField.name)) return;
+
         if (subField.required) {
             result.required!.push(subField.name);
         }

test/redefine.spec.ts

@@ -0,0 +1,47 @@
+import { describe, expect, it } from '@jest/globals';
+import { toJSONSchema } from '../src';
+
+describe('Redefine', () => {
+    // This is nasty, but apparently some app configs have it like that...
+    it('should survive redefinition of properties', () => {
+        const field = {
+            type: 'collection',
+            spec: [
+                {
+                    name: 'name',
+                    type: 'text',
+                    label: 'Name',
+                },
+                {
+                    name: 'age',
+                    type: 'uinteger',
+                    label: 'Age',
+                },
+                {
+                    name: 'name',
+                    type: 'text',
+                    label: 'Full Name',
+                },
+            ],
+        };
+        const schema = toJSONSchema(field);
+        expect(schema).toStrictEqual({
+            description: undefined,
+            properties: {
+                age: {
+                    description: undefined,
+                    title: 'Age',
+                    type: 'number',
+                },
+                name: {
+                    description: undefined,
+                    title: 'Name',
+                    type: 'string',
+                },
+            },
+            required: [],
+            title: undefined,
+            type: 'object',
+        });
+    });
+});