Refactor i18n middleware language finders

[stanislas-m]

• Split language finders into separate functions
• Refactor LanguageFinder type
• Generalize Language finders options
• Add a new path prefix language finding strategy
• Ensure setups with default config won't break

Related to: gobuffalo/docs#133

[markbates]

@stanislas-m this appears to be a breaking change, how do you propose handling that? via buffalo update?

[stanislas-m]

@markbates buffalo update seems to be the obvious way, yeah. This should only affect projects with a customized i18n middleware (I don't think they are legion), but we can at least give some help for those cases.

[markbates]

The bare minimum we add to buffalo update should at least detect they’re using stuff that changed and print a warning that they should change things. The nice to have would be doing the code changes for them, if possible.

[stanislas-m]

buffalo update should take care of these cases:

T.CookieName = "language" // Becomes T.LanguageFinderOptions["CookieName"] = "language"
T.SessionName = "language" // Becomes T.LanguageFinderOptions["SessionName"] = "language"
// This one needs refactor:
T.LanguageFinder = func(t *i18n.Translator, c buffalo.Context) []string {
	langs := make([]string, 0)
	if cookie, err := c.Request().Cookie(t.CookieName); err == nil {
		if cookie.Value != "" {
			langs = append(langs, cookie.Value)
		}
	}
	langs = append(langs, t.DefaultLanguage)
	return langs
}

[markbates]

@stanislas-m can you make the changes needed to buffalo update to make sure this doesn't affect too many people?

[stanislas-m]

@markbates Sure, it's on my todo list. :)

[stanislas-m]

@markbates The update works on my side, but a specific case like the following will break (since I've removed the CookieName field):

T.LanguageFinder = func(t *i18n.Translator, c buffalo.Context) []string {
	langs := make([]string, 0)
	if cookie, err := c.Request().Cookie(t.CookieName); err == nil {
		if cookie.Value != "" {
			langs = append(langs, cookie.Value)
		}
	}
	langs = append(langs, t.DefaultLanguage)
	return langs
}

I issue a warning for this one with the update command, is it enough?

[markbates]

what should they use instead?

[stanislas-m]

I just added more infos in the last commit, thanks!