prevent object representations from including properties without values ...

[activefx]

...(fixes #4)

[bobbytables]

Thanks for the PR.

This is scares me because sometimes you want false as a value to be rendered. This would prevent that, the same with null.

I'd probably opt to have something like

property :name, omit_nil: true

[activefx]

Great point, completely forgot about false. Ill update the request.

[bobbytables]

Do you have any thoughts on omit_nil: true as an option while defining properties?

[activefx]

That would be the quickest fix. The other thought I had was differentiating between optional and required properties, where optional properties with nil values would not be included and required properties would always be set to null. But that gets complex quickly when working with the scopes, and again there might be an edge case.

Another possibility could be to add an optional reduce / finalize function that takes place after the representation_for mapping.

kartograph do
  mapping User

  property :name, scopes: :read
  property :avatar, scopes: [:read, :create] 

  reduce { |hash| hash.delete_if { |k, v| v.nil? } }, scopes: :create
end

[bobbytables]

The finalize mechanism is an interesting option. I'm mostly concerned with it being viewed as an option to use callbacks on serialization. Which is something I'd really like to avoid. I think the use-case for giving omit_nil: true is great.

[activefx]

What are your thoughts on allow_nil instead of omit_nil? On API put requests that only update a select few attributes, passing the rest of the attributes as nil values may cause them to become unset. By default, I suggest that nil values are not included in the representation.

[davidcelis]

I would personally hesitate to call this an issue. As Kartograph's stated intention is to be used for APIs, the mappings it returns should always have the same structure. This means values should be shown as null as opposed to removed entirely. While I understand your use case here, I would urge you not to make properties in your API responses optional, instead letting clients handle null values