This is an extremely weird one. I'm using datamapper for dynamo and dynamolocal in typescript to test my stuff. For some reason it overwrites one object field and I can't figure out why.

I'm seeding the table like so:

private async seedTable() {
        // FIRST PART
        for (const obj of [...objects]) {
            const toSave = new MyObject().fromPartial({
                ...obj
            });
            console.log(`myBool: ${toSave.myBool}`);
            await this.ddbMapper.put(toSave);
        }

        // SECOND PART
        await this.ddbMapper.put(
            new MyObject().fromPartial({
                ...objects[0],
                objId: "test",
                myBool: false
            })
        );
    }

In this previous snippet, the objects from the for loop will print: "myBool: false"

however in the table they will be true (what?)

the second part where I hardcode the object, it's getting saved with myBool: false as I would expect

If I overwrite the value it works but if I keep the original object it switches to true for no apparent reason.

this is the fromPartial implementation

public fromPartial(data: Partial<MyObject>): MyObject {
        Object.assign(this, data);
        return this;
    }

is this a bug from dynamodb / dynamodb-local / my implementation / javascript / typescript ? does anybody have a clue into what could be the source of the issue ?

Edit: ddbmapper is the DataMapper class from dynamodb-data-mapper