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tpl/collections: Add group template func
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This extends the page grouping in Hugo with a template function that allows for ad-hoc grouping.

A made-up example:

```
{{ $cool := where .Site.RegularPages "Params.cool" true | group "cool" }}
{{ $blue := where .Site.RegularPages "Params.blue" true | group "blue" }}
{{ $paginator := .Paginate (slice $cool $blue) }}
```

Closes gohugoio#4865
bep committed Sep 8, 2018

Verified

This commit was created on GitHub.com and signed with GitHub’s verified signature.
1 parent cfda13b commit f4897ac
Showing 8 changed files with 130 additions and 5 deletions.
21 changes: 21 additions & 0 deletions common/collections/collections.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
// Copyright 2018 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Package collections contains common Hugo functionality related to collection
// handling.
package collections

// Grouper defines a very generic way to group items by a given key.
type Grouper interface {
Group(key interface{}, items interface{}) (interface{}, error)
}
2 changes: 1 addition & 1 deletion common/types/types.go
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Copyright 2017-present The Hugo Authors. All rights reserved.
// Copyright 2018 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
3 changes: 3 additions & 0 deletions hugolib/page.go
Original file line number Diff line number Diff line change
@@ -23,6 +23,7 @@ import (

"github.com/gohugoio/hugo/media"

"github.com/gohugoio/hugo/common/collections"
"github.com/gohugoio/hugo/common/maps"

"github.com/gohugoio/hugo/langs"
@@ -70,6 +71,8 @@ var (

// Assert that it implements the interface needed for related searches.
_ related.Document = (*Page)(nil)

_ collections.Grouper = Page{}
)

const (
12 changes: 8 additions & 4 deletions hugolib/pageGroup.go
Original file line number Diff line number Diff line change
@@ -298,8 +298,12 @@ func (p Pages) GroupByParamDate(key string, format string, order ...string) (Pag
}

// Group creates a PageGroup from a key and a Pages object
func (p *Page) Group(key interface{}, pages Pages) (PageGroup, error) {
pageGroup := PageGroup{Key: key, Pages: pages}

return pageGroup, nil
// This method is not meant for external use. It got its non-typed arguments to satisfy
// a very generic interface in the tpl package.
func (p Page) Group(key interface{}, in interface{}) (interface{}, error) {
pages, err := toPages(in)
if err != nil {
return nil, err
}
return PageGroup{Key: key, Pages: pages}, nil
}
26 changes: 26 additions & 0 deletions hugolib/pageGroup_test.go
Original file line number Diff line number Diff line change
@@ -20,6 +20,7 @@ import (
"testing"

"github.com/spf13/cast"
"github.com/stretchr/testify/require"
)

type pageGroupTestObject struct {
@@ -455,3 +456,28 @@ func TestGroupByParamDateWithEmptyPages(t *testing.T) {
t.Errorf("PagesGroup isn't empty. It should be %#v, got %#v", nil, groups)
}
}

func TestGroupFunc(t *testing.T) {
assert := require.New(t)

pageContent := `
---
title: "Page"
---
`
b := newTestSitesBuilder(t)
b.WithSimpleConfigFile().
WithContent("page1.md", pageContent, "page2.md", pageContent).
WithTemplatesAdded("index.html", `
{{ $cool := .Site.RegularPages | group "cool" }}
{{ $cool.Key }}: {{ len $cool.Pages }}
`)
b.CreateSites().Build(BuildCfg{})

assert.Equal(1, len(b.H.Sites))
require.Len(t, b.H.Sites[0].RegularPages, 2)

b.AssertFileContent("public/index.html", "cool: 2")
}
25 changes: 25 additions & 0 deletions tpl/collections/collections.go
Original file line number Diff line number Diff line change
@@ -23,6 +23,7 @@ import (
"strings"
"time"

"github.com/gohugoio/hugo/common/collections"
"github.com/gohugoio/hugo/common/maps"
"github.com/gohugoio/hugo/common/types"
"github.com/gohugoio/hugo/deps"
@@ -311,6 +312,30 @@ func (ns *Namespace) Intersect(l1, l2 interface{}) (interface{}, error) {
}
}

// Group groups a set of elements by the given key.
// This is currently only supported for Pages.
func (ns *Namespace) Group(key interface{}, items interface{}) (interface{}, error) {
if key == nil {
return nil, errors.New("nil is not a valid key to group by")
}

tp := reflect.TypeOf(items)
switch tp.Kind() {
case reflect.Array, reflect.Slice:
tp = tp.Elem()
if tp.Kind() == reflect.Ptr {
tp = tp.Elem()
}
in := reflect.Zero(tp).Interface()
switch vv := in.(type) {
case collections.Grouper:
return vv.Group(key, items)
}
}

return nil, fmt.Errorf("grouping not supported for type %T", items)
}

// IsSet returns whether a given array, channel, slice, or map has a key
// defined.
func (ns *Namespace) IsSet(a interface{}, key interface{}) (bool, error) {
41 changes: 41 additions & 0 deletions tpl/collections/collections_test.go
Original file line number Diff line number Diff line change
@@ -75,6 +75,47 @@ func TestAfter(t *testing.T) {
}
}

type tstGrouper struct {
}

type tstGroupers []*tstGrouper

func (g tstGrouper) Group(key interface{}, items interface{}) (interface{}, error) {
ilen := reflect.ValueOf(items).Len()
return fmt.Sprintf("%v(%d)", key, ilen), nil
}

func TestGroup(t *testing.T) {
t.Parallel()

ns := New(&deps.Deps{})

for i, test := range []struct {
key interface{}
items interface{}
expect interface{}
}{
{"a", []*tstGrouper{&tstGrouper{}, &tstGrouper{}}, "a(2)"},
{"b", tstGroupers{&tstGrouper{}, &tstGrouper{}}, "b(2)"},
{"a", []tstGrouper{tstGrouper{}, tstGrouper{}}, "a(2)"},
{"a", []*tstGrouper{}, "a(0)"},
{"a", []string{"a", "b"}, false},
{nil, []*tstGrouper{&tstGrouper{}, &tstGrouper{}}, false},
} {
errMsg := fmt.Sprintf("[%d] %v", i, test)

result, err := ns.Group(test.key, test.items)

if b, ok := test.expect.(bool); ok && !b {
require.Error(t, err, errMsg)
continue
}

require.NoError(t, err, errMsg)
require.Equal(t, test.expect, result, errMsg)
}
}

func TestDelimit(t *testing.T) {
t.Parallel()

5 changes: 5 additions & 0 deletions tpl/collections/init.go
Original file line number Diff line number Diff line change
@@ -138,6 +138,11 @@ func init() {
[][2]string{},
)

ns.AddMethodMapping(ctx.Group,
[]string{"group"},
[][2]string{},
)

ns.AddMethodMapping(ctx.Seq,
[]string{"seq"},
[][2]string{

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