feat: can set a maximum of selected items [maxSelectedItems] when mult…

[benjaminlefevre]

…iple selection is activated

#181

[coveralls]

Coverage increased (+0.07%) to 90.052% when pulling 6159db1 on benjaminlefevre:max_selected_items_when_multiple into f15fafc on ng-select:master.

[anjmao]

Nice work 👍 Added few comments regarding code style, but if you don't have time let me know, I will merge it and fix.

[anjmao]

Move this public method before all private methods.

[varnastadeus]

I also would suggest renaming this method to less verbose, eg.: maxItemsSelected or similar

[anjmao]

You can remove that method and use one prod itemsList directly

if (this.isDisabled || this.isOpen || this.itemsList.isMaximumNumberOfSelectedItemsReaches()) {

[andreasfranz]

I think in this case it should be this.itemsList.isMaximumNumberOfSelectedItemsReached() then

[benjaminlefevre]

I will fix the issues this evening after work, thank you for the review

[andreasfranz]

Hi @anjmao,
I also thought of such a feature recently, because I would need it for my project too. I think the suggested solution of @benjaminlefevre as a certain drawback: From a user's point of view it hard to recognize why the select box is suddenly disabled (without any further hint in the user interface).

As using a single select behaves differently: Once you select a new option is just replaces the previous one. Maybe this could also be an option, just replace the last item in the list with the newly selected. I am not sure if this is a better behavior than disabling the select box.
What do you think?

[anjmao]

@andreasfranz replacing last selected item can look a bit strange and user always can remove item from the list so he have a choose. I think current implementation is good and it would be even less clear if dropdown is opened but you can't select items because max items are reached. Best approach would be to add some kind of hint (label) for user that he can select only x items.

[benjaminlefevre]

I made the fixes.

And yes, I made a choice, which seemed to me the most natural: not to replace the last item, but to block the selection of items.
It would be nice to find a visual trick to indicate the max is reached, I thought of a tooltip but what about the internationalization.... I think it could be done afterwards, since for the moment this is a functionality which will not be used a lot.