Transformation gets triggered for missing field

[midknight41]

Transformation gets triggered for missing field

[midknight41]

I agree the behaviour is inconsistent and probably undesirable. In my mind, if the source is absent the the transform should not execute. I'll have a look at it. This should work for you in the meantime:

const map = createMapper();

map
  .map("foo").to("foo")
  .map("foo").to("baz", foo => { if(foo) return "val: " + foo });

[apricote]

Again, thank you for all the work you are doing.

[midknight41]

I've had a deeper look at this and I believe the current behaviour is actually correct. The logic is that once you provide a transform, map-factory can no longer guess your intention. As such, it hands over complete control to the developer to decide what to do. For an undefined or null you might want to create some structure...maybe you don't. I'll update the documentation to make the expected behaviour clearer.

That said, the behaviour could be modified provided that the person using map-factory can make that decision.

Something like this:

const options = {
  alwaysTransform: false
};

const mapper = createMapper(options);
const source = {};

const result = mapper
  .map("foo").to("foo")
  .map("foo").to("baz", foo => return "val: " + foo)
  .execute(source);

expect(result).to.equal(source);

Changing the default behaviour would be a breaking change so I don't want to do that.

Would that work for you?

[apricote]

Absolutely, thank you 👍

By the way, i think the package is great and it really helps me.

[midknight41]

Glad you like it!

[midknight41]

Behaviour modification features added with 1.7.0. See README for details.

Sorry it took so long. I had to do a major refactoring under the hood!