Add last template function

`last` allows the user to select the last X items of
and array.
This commit is contained in:
Ariejan de Vroom 2015-06-11 00:11:47 +02:00 committed by Bjørn Erik Pedersen
parent 627d016cc9
commit 0a2e5424ab
2 changed files with 71 additions and 0 deletions

View file

@ -388,6 +388,42 @@ func First(limit interface{}, seq interface{}) (interface{}, error) {
return seqv.Slice(0, limitv).Interface(), nil return seqv.Slice(0, limitv).Interface(), nil
} }
// Last is exposed to templates, to iterate over the last N items in a
// rangeable list.
func Last(limit interface{}, seq interface{}) (interface{}, error) {
if limit == nil || seq == nil {
return nil, errors.New("both limit and seq must be provided")
}
limitv, err := cast.ToIntE(limit)
if err != nil {
return nil, err
}
if limitv < 1 {
return nil, errors.New("can't return negative/empty count of items from sequence")
}
seqv := reflect.ValueOf(seq)
seqv, isNil := indirect(seqv)
if isNil {
return nil, errors.New("can't iterate over a nil value")
}
switch seqv.Kind() {
case reflect.Array, reflect.Slice, reflect.String:
// okay
default:
return nil, errors.New("can't iterate over " + reflect.ValueOf(seq).Type().String())
}
if limitv > seqv.Len() {
limitv = seqv.Len()
}
return seqv.Slice(seqv.Len()-limitv, seqv.Len()).Interface(), nil
}
// After is exposed to templates, to iterate over all the items after N in a // After is exposed to templates, to iterate over all the items after N in a
// rangeable list. It's meant to accompany First // rangeable list. It's meant to accompany First
func After(index interface{}, seq interface{}) (interface{}, error) { func After(index interface{}, seq interface{}) (interface{}, error) {
@ -1288,6 +1324,7 @@ func init() {
"relURL": func(a string) template.HTML { return template.HTML(helpers.RelURL(a)) }, "relURL": func(a string) template.HTML { return template.HTML(helpers.RelURL(a)) },
"markdownify": Markdownify, "markdownify": Markdownify,
"first": First, "first": First,
"last": Last,
"after": After, "after": After,
"where": Where, "where": Where,
"delimit": Delimit, "delimit": Delimit,

View file

@ -253,6 +253,40 @@ func TestFirst(t *testing.T) {
} }
} }
func TestLast(t *testing.T) {
for i, this := range []struct {
count interface{}
sequence interface{}
expect interface{}
}{
{int(2), []string{"a", "b", "c"}, []string{"b", "c"}},
{int32(3), []string{"a", "b"}, []string{"a", "b"}},
{int64(2), []int{100, 200, 300}, []int{200, 300}},
{100, []int{100, 200}, []int{100, 200}},
{"1", []int{100, 200, 300}, []int{300}},
{int64(-1), []int{100, 200, 300}, false},
{"noint", []int{100, 200, 300}, false},
{1, nil, false},
{nil, []int{100}, false},
{1, t, false},
} {
results, err := Last(this.count, this.sequence)
if b, ok := this.expect.(bool); ok && !b {
if err == nil {
t.Errorf("[%d] First didn't return an expected error", i)
}
} else {
if err != nil {
t.Errorf("[%d] failed: %s", i, err)
continue
}
if !reflect.DeepEqual(results, this.expect) {
t.Errorf("[%d] First %d items, got %v but expected %v", i, this.count, results, this.expect)
}
}
}
}
func TestAfter(t *testing.T) { func TestAfter(t *testing.T) {
for i, this := range []struct { for i, this := range []struct {
count interface{} count interface{}