Range through times to pretty print by year - templates

Question

Currently I'm printing post archive dates like so with https://play.golang.org/p/P1-sAo5Qy8:
2009 Nov 10»Something happened in 2009
2005 Nov 10»Something happened 10 years ago
2009 Jun 10»Summer of 2009
Though I think it's nicer to print by year:
2009
2009 Nov 10»Something happened in 2009
2009 Jun 10»Summer of 2009
2005
2005 Nov 10»Something happened 10 years ago
How would I range reverse chronically over the Posts PostDate, to print the grouping that I want? Can it be done all in the template?

Answer 1

Implement the sort.Interface on your Posts struct, then sort it in reverse order.
type Posts struct {
Posts []Post
}
func (p Posts) Len() int {
return len(p.Posts)
}
func (p Posts) Less(i, j int) bool {
return p.Posts[i].PostDate.Before(p.Posts[j].PostDate)
}
func (p Posts) Swap(i, j int) {
p.Posts[i], p.Posts[j] = p.Posts[j], p.Posts[i]
}
and
posts := Posts{p}
sort.Sort(sort.Reverse(posts))
That will give you the posts in the sequence you want them.
Next you'll have to implement a func using a closure so you can check if the current year is the same as the one for the last post to get the grouping by year. If yes output just the post, otherwise output a header with the year followed by the post.
currentYear := "1900"
funcMap := template.FuncMap{
"newYear": func(t string) bool {
if t == currentYear {
return false
} else {
currentYear = t
return true
}
},
}
and to use it:
{{ range . }}{{ if newYear (.PostDate.Format "2006") }}<li><h1>{{ .PostDate.Format "2006" }}</h1></li>{{ end }}
See a working example on the Playground.