initialMonth should not update after first mounted

[willmcclellan]

I'm not sure if this is the intended behaviour, but I expected the initialMonth property to only be relevant on the first mount of the component. So you set an initialMonth but subsequent renders ignore it.

The current behaviour here:

https://github.com/gpbl/react-day-picker/blob/master/src/DayPicker.js#L80-L84

... updates the current month to the initialMonth when receiving props which, if you aren't storing/updating the current month in state when clicking next/prev, means the months don't switch if initialMonth is always the same value.

If that is the intended behaviour, then maybe the naming of initialMonth should be changed as it doesn't fit with how it actually works?

[gpbl]

Yes I believe you are right, implementers should use the showMonth instance method instead. I think this is a leftover from some early release, but it may lead to some unintended effects.

[davidspiess]

I'm not happy about that change. How would i now be able to (re)render the calendar, when my date variable in my store changes?

[gpbl]

@davidspiess you can use the ref prop and the this.daypicker.showMonth(newMonthFromProps) in componentDidUpdate. Would that work for you?

[davidspiess]

@gpbl yes it works that way, but i think it should be a prop like it was. When my state changes, i want my UI to reflect that. With this behavior have to call a method when this is the case, which goes against the whole purpose of react.

[gpbl]

@davidspiess the problem lies in the prop's name: people expect initialMonth to work just for the first render (as reported by @willmcclellan here), similarly to the defaultValue in uncontrolled components.

I think i should add a new month prop behaving like the previous initialMonth - what do you think?

[davidspiess]

That would be awesome! 👍