Support interface type

Signed-off-by: moznion <moznion@mail.moznion.net>

Author: moznion

tests/transformer.test.ts

@@ -265,4 +265,24 @@ describe('dynamodb record transform', () => {
     expect(record['kvMapToBigint']).toEqual({ M: { bigint: { N: '890' } } });
     expect(Object.keys(record)).toHaveLength(6);
   });
+
+  test('interface', () => {
+    interface Interface {
+      readonly id: number;
+      readonly name: string;
+      readonly tags: Map<string, string>;
+    }
+    const record: Record<string, AttributeValue> = dynamodbRecord<Interface>({
+      id: 12345,
+      name: 'John Doe',
+      tags: new Map<string, string>([
+        ['foo', 'bar'],
+        ['buz', 'qux'],
+      ]),
+    });
+    expect(record['name']).toEqual({ S: 'John Doe' });
+    expect(record['tags']).toEqual({ M: { foo: { S: 'bar' }, buz: { S: 'qux' } } });
+    expect(record['id']).toEqual({ N: '12345' });
+    expect(Object.keys(record)).toHaveLength(3);
+  });
 });

transformer.ts

@@ -85,8 +85,11 @@ function visitNode(node: ts.Node, program: ts.Program): ts.Node | undefined {
 
       const propName = prop.name;
 
-      if (prop.valueDeclaration.kind !== ts.SyntaxKind.Parameter) {
-        const msg = `unexpected error: a property "${propName}" of the type "${typeName}" doesn't have parameter kind`;
+      if (
+        prop.valueDeclaration.kind !== ts.SyntaxKind.Parameter &&
+        prop.valueDeclaration.kind !== ts.SyntaxKind.PropertySignature
+      ) {
+        const msg = `a property "${propName}" of the type "${typeName}" doesn't have parameter kind; maybe the ${typeName} is not class of interface`;
         if (shouldLenientTypeCheck) {
           warn(msg);
           return undefined;