create: Use archetype template as-is as a Go template

This commit removes the fragile front matter decoding, and takes the provided archetype file as-is and processes it as a template.

This also means that we no longer will attempt to fill in default values for `title` and `date`.

The upside is that it is now easy to create these values in a dynamic way:

```toml
+++
title = {{ .BaseFileName | title }}
date = {{ .Date }}
draft = true
+++
```

You can currently use all of Hugo's template funcs, but the data context is currently very shallow:

* `.Type` gives the archetype kind provided
* `.Name` gives the target file name without extension.
* `.Path` gives the target file name
* `.Date` gives the current time as RFC3339 formatted string

The above  will probably be extended in #1629.

Fixes #452
Updates #1629

1 files changed, 94 insertions, 0 deletions

diff --git a/create/content_template_handler.go b/create/content_template_handler.go
new file mode 100644
index 000000000..9903c3dec
--- /dev/null
+++ b/create/content_template_handler.go
@@ -0,0 +1,94 @@
+// Copyright 2017 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 create
+
+import (
+	"bytes"
+	"fmt"
+	"time"
+
+	"github.com/gohugoio/hugo/source"
+
+	"github.com/gohugoio/hugo/hugolib"
+	"github.com/gohugoio/hugo/tpl"
+	"github.com/spf13/afero"
+)
+
+const (
+	archetypeTemplateTemplate = `+++
+title = "{{ replace .BaseFileName "-" " " | title }}"
+date = {{ .Date }}
+draft = true
++++`
+)
+
+func executeArcheTypeAsTemplate(s *hugolib.Site, kind, targetPath, archetypeFilename string) ([]byte, error) {
+
+	var (
+		archetypeContent  []byte
+		archetypeTemplate []byte
+		err               error
+	)
+
+	sp := source.NewSourceSpec(s.Deps.Cfg, s.Deps.Fs)
+	f := sp.NewFile(targetPath)
+
+	data := struct {
+		Type string
+		Date string
+		*source.File
+	}{
+		Type: kind,
+		Date: time.Now().Format(time.RFC3339),
+		File: f,
+	}
+
+	if archetypeFilename == "" {
+		// TODO(bep) archetype revive the issue about wrong tpl funcs arg order
+		archetypeTemplate = []byte(archetypeTemplateTemplate)
+	} else {
+		archetypeTemplate, err = afero.ReadFile(s.Fs.Source, archetypeFilename)
+		if err != nil {
+			return nil, fmt.Errorf("Failed to read archetype file %q: %s", archetypeFilename, err)
+		}
+
+	}
+
+	// Reuse the Hugo template setup to get the template funcs properly set up.
+	templateHandler := s.Deps.Tmpl.(tpl.TemplateHandler)
+	if err := templateHandler.AddTemplate("_text/archetype", string(archetypeTemplate)); err != nil {
+		return nil, fmt.Errorf("Failed to parse archetype file %q: %s", archetypeFilename, err)
+	}
+
+	templ := templateHandler.Lookup("_text/archetype")
+
+	var buff bytes.Buffer
+	if err := templ.Execute(&buff, data); err != nil {
+		return nil, fmt.Errorf("Failed to process archetype file %q: %s", archetypeFilename, err)
+	}
+
+	archetypeContent = buff.Bytes()
+
+	if !bytes.Contains(archetypeContent, []byte("date")) || !bytes.Contains(archetypeContent, []byte("title")) {
+		// TODO(bep) remove some time in the future.
+		s.Log.FEEDBACK.Println(fmt.Sprintf(`WARNING: date and/or title missing from archetype file %q. 
+From Hugo 0.24 this must be provided in the archetype file itself, if needed. Example:
+%s
+`, archetypeFilename, archetypeTemplateTemplate))
+
+	}
+
+	return archetypeContent, nil
+
+}