Set the default value for unmarshaller

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

Author: moznion

lib/dynamodb_item_field.ts

@@ -72,7 +72,7 @@ export class ArrayField implements DynamodbItemField {
     return ts.factory.createPropertyAssignment(
       this.fieldName,
       ts.factory.createIdentifier(
-        `${argName}['${this.fieldName}']?.L?.map(v => ${valueConvertingOp.leftOp}v.${this.valueType.kind}${valueConvertingOp.rightOp})`,
+        `${argName}['${this.fieldName}']?.L?.map(v => ${valueConvertingOp.leftOp}v.${this.valueType.kind}${valueConvertingOp.rightOp}) || []`,
       ),
     );
   }
@@ -119,7 +119,7 @@ export class SetField implements DynamodbItemField {
     return ts.factory.createPropertyAssignment(
       this.fieldName,
       ts.factory.createIdentifier(
-        `${argName}['${this.fieldName}']?.${this.valueType.kind}S?.map(v => ${valueConvertingOp.leftOp}v${valueConvertingOp.rightOp})`,
+        `${argName}['${this.fieldName}']?.${this.valueType.kind}S?.map(v => ${valueConvertingOp.leftOp}v${valueConvertingOp.rightOp}) || new Set()`,
       ),
     );
   }

tests/from_dynamodb_record_transformer.test.ts

@@ -237,4 +237,21 @@ describe('from dynamodb record transform', () => {
     expect(got.mapToBigint).toEqual(new Map([['bigint', BigInt(789)]]));
     expect(got.kvMapToBigint).toEqual({ bigint: BigInt(890) });
   });
+
+  test('for default values', () => {
+    interface Interface {
+      readonly num?: number;
+      readonly numArray: Array<number>;
+      readonly numSet: Set<number>;
+      readonly mapToNumber: Map<string, number>;
+      readonly kvMapToNumber: { [key: string]: number };
+    }
+
+    const got = fromDynamodbRecord<Interface>({});
+    expect(got.num).toBeUndefined();
+    expect(got.numArray).toEqual([]);
+    expect(got.numSet).toEqual(new Set());
+    expect(got.mapToNumber).toEqual(new Map());
+    expect(got.kvMapToNumber).toEqual({});
+  });
 });