PrevProps the same as current props

[lomboboo]

Hi and thanks for awesome library.

I use react-i18next in my project and I've got an issue when I want to access prevProps within ComponentDidUpdate for example. In this case language field in the i18n object is the same as this.props. You can see it in this demo .

I took a look in the core and found that inside translate HOC you mutate i18n object.

Is there any reason why it was implemented this way? I'd really like to have prevProps has correct values

[jamuhl]

it is the same object (singleton) and not an immutable...it just try to look it up in the different possible locations (context, props, ...)

what exactly is your issue - why you need that previous language?

[lomboboo]

Thanks for quick response.

I have a case where I need to do some async calls when language changed. So I'd have condition in the ComponentDidMount something like this.props.i18n.language !== prevProps.i18n.language then do some logic.

Although i18next has languageChanged event, it's inconvenient to use in the react app. It'd be much simpler if prevProps worked "react like".

[jamuhl]

hm...then i would suggest we pass lng from translate to component as a prop...the i18n instance is based on i18next and can't be really changed therefor

so adding it to the I18n render props which is used in translate hoc and from there add it to components props?!?

[lomboboo]

I can work on PR, but I'm not sure what are you referring to. You're talking about pass as prop here?

[jamuhl]

yes and also here: https://github.com/i18next/react-i18next/blob/master/src/I18n.js#L124

basically passing it from that I18n to the line you showed above...

feel free to make a PR