Nested grid removed from Widget when updating contents

[akosfekete]

Subject of the issue

When I update a widget with a nested grid using update(els: GridStackElement, opt: GridStackWidget), and provide content in the opt parameter, the nested grid is also removed (even though the subGridOpts field is not present in the opt parameter).

Your environment

• version of gridstack.js: tried on 8.3.0-dev, 8.3.0, 8.2.3, 7.3.0
• which browser/OS: Firefox / Chrome, Linux / Windows

Steps to reproduce

• Create a nested grid
• Call update() on it with an opt parameter like this: {content: '<div>some content</div>'}
• JSFiddle: https://jsfiddle.net/1yr8ngju/

Expected behavior

The nested grid should not be removed, only the content that has been set originally when creating the widget.

I created a fork with a quick "fix": master...akosfekete:gridstack.js:sub-grid-update-issue
I'm not sure if this is intended in some way, but since the documentation says that "Only those set will be updated", I'd epect the nested grid to remain.

[adumesny]

this isn't really a bug - if the item has a subgrid content, and you explicitly say update(el, {content: 'foo'}) then of course it's going to override whatever content you had with 'foo' - content and subGridOpts are emutually exclusive if you have them both json today I think... will have to check. the above case incrementally has both though....

[adumesny]

actually you code seems clean enough, please create a code review (so you can get credit) with that comment addressed
#2385

[adumesny]

fixed the right way - don't forget to donate if you find this lib useful!