This more or less completes the simplification of the template handling code in Hugo started in v0.62.
The main motivation was to fix a long lasting issue about a crash in HTML content files without front matter.
But this commit also comes with a big functional improvement.
As we now have moved the base template evaluation to the build stage we now use the same lookup rules for `baseof` as for `list` etc. type of templates.
This means that in this simple example you can have a `baseof` template for the `blog` section without having to duplicate the others:
```
layouts
├── _default
│ ├── baseof.html
│ ├── list.html
│ └── single.html
└── blog
└── baseof.html
```
Also, when simplifying code, you often get rid of some double work, as shown in the "site building" benchmarks below.
These benchmarks looks suspiciously good, but I have repeated the below with ca. the same result. Compared to master:
```
name old time/op new time/op delta
SiteNew/Bundle_with_image-16 13.1ms ± 1% 10.5ms ± 1% -19.34% (p=0.029 n=4+4)
SiteNew/Bundle_with_JSON_file-16 13.0ms ± 0% 10.7ms ± 1% -18.05% (p=0.029 n=4+4)
SiteNew/Tags_and_categories-16 46.4ms ± 2% 43.1ms ± 1% -7.15% (p=0.029 n=4+4)
SiteNew/Canonify_URLs-16 52.2ms ± 2% 47.8ms ± 1% -8.30% (p=0.029 n=4+4)
SiteNew/Deep_content_tree-16 77.9ms ± 1% 70.9ms ± 1% -9.01% (p=0.029 n=4+4)
SiteNew/Many_HTML_templates-16 43.0ms ± 0% 37.2ms ± 1% -13.54% (p=0.029 n=4+4)
SiteNew/Page_collections-16 58.2ms ± 1% 52.4ms ± 1% -9.95% (p=0.029 n=4+4)
name old alloc/op new alloc/op delta
SiteNew/Bundle_with_image-16 3.81MB ± 0% 2.22MB ± 0% -41.70% (p=0.029 n=4+4)
SiteNew/Bundle_with_JSON_file-16 3.60MB ± 0% 2.01MB ± 0% -44.20% (p=0.029 n=4+4)
SiteNew/Tags_and_categories-16 19.3MB ± 1% 14.1MB ± 0% -26.91% (p=0.029 n=4+4)
SiteNew/Canonify_URLs-16 70.7MB ± 0% 69.0MB ± 0% -2.40% (p=0.029 n=4+4)
SiteNew/Deep_content_tree-16 37.1MB ± 0% 31.2MB ± 0% -15.94% (p=0.029 n=4+4)
SiteNew/Many_HTML_templates-16 17.6MB ± 0% 10.6MB ± 0% -39.92% (p=0.029 n=4+4)
SiteNew/Page_collections-16 25.9MB ± 0% 21.2MB ± 0% -17.99% (p=0.029 n=4+4)
name old allocs/op new allocs/op delta
SiteNew/Bundle_with_image-16 52.3k ± 0% 26.1k ± 0% -50.18% (p=0.029 n=4+4)
SiteNew/Bundle_with_JSON_file-16 52.3k ± 0% 26.1k ± 0% -50.16% (p=0.029 n=4+4)
SiteNew/Tags_and_categories-16 336k ± 1% 269k ± 0% -19.90% (p=0.029 n=4+4)
SiteNew/Canonify_URLs-16 422k ± 0% 395k ± 0% -6.43% (p=0.029 n=4+4)
SiteNew/Deep_content_tree-16 401k ± 0% 313k ± 0% -21.79% (p=0.029 n=4+4)
SiteNew/Many_HTML_templates-16 247k ± 0% 143k ± 0% -42.17% (p=0.029 n=4+4)
SiteNew/Page_collections-16 282k ± 0% 207k ± 0% -26.55% (p=0.029 n=4+4)
```
Fixes#6716Fixes#6760Fixes#6768Fixes#6778
This commit also
* revises the change detection for templates used by content files in server mode.
* Adds a Page.RenderString method
Fixes#6545Fixes#4663Closes#6043
Before this commit, `Suffix` on `MediaType` was used both to set a custom file suffix and as a way to augment the mediatype definition (what you see after the "+", e.g. "image/svg+xml").
This had its limitations. For one, it was only possible with one file extension per MIME type.
Now you can specify multiple file suffixes using "suffixes", but you need to specify the full MIME type
identifier:
[mediaTypes]
[mediaTypes."image/svg+xml"]
suffixes = ["svg", "abc ]
In most cases, it will be enough to just change:
[mediaTypes]
[mediaTypes."my/custom-mediatype"]
suffix = "txt"
To:
[mediaTypes]
[mediaTypes."my/custom-mediatype"]
suffixes = ["txt"]
Hugo will still respect values set in "suffix" if no value for "suffixes" is provided, but this will be removed in a future release.
Note that you can still get the Media Type's suffix from a template: {{ $mediaType.Suffix }}. But this will now map to the MIME type filename.
Fixes#4920
This should allow for less duplication of templates. Before this commit it was possible to override the content page of a given page/section, but only one page at a time.
Full "template sets" can now be inherited by setting `type: blog` etc. in the section content page's front matter, and that type will be considered when looking for layouts for all pages in that section.
For nested sections, it will use consider both `type` set in the current section first, then `type` set in the first section below home, e.g. `/docs`.
This commit also adds a new Page method: `FirstSection`. This navigates up to the first section below home (e.g. `/docs`). For the home page it will return itself.
Fixes#4891
This commit adds support for theme composition and inheritance in Hugo.
With this, it helps thinking about a theme as a set of ordered components:
```toml
theme = ["my-shortcodes", "base-theme", "hyde"]
```
The theme definition example above in `config.toml` creates a theme with the 3 components with presedence from left to right.
So, Hugo will, for any given file, data entry etc., look first in the project, and then in `my-shortcode`, `base-theme` and lastly `hyde`.
Hugo uses two different algorithms to merge the filesystems, depending on the file type:
* For `i18n` and `data` files, Hugo merges deeply using the translation id and data key inside the files.
* For `static`, `layouts` (templates) and `archetypes` files, these are merged on file level. So the left-most file will be chosen.
The name used in the `theme` definition above must match a folder in `/your-site/themes`, e.g. `/your-site/themes/my-shortcodes`. There are plans to improve on this and get a URL scheme so this can be resolved automatically.
Also note that a component that is part of a theme can have its own configuration file, e.g. `config.toml`. There are currently some restrictions to what a theme component can configure:
* `params` (global and per language)
* `menu` (global and per language)
* `outputformats` and `mediatypes`
The same rules apply here: The left-most param/menu etc. with the same ID will win. There are some hidden and experimental namespace support in the above, which we will work to improve in the future, but theme authors are encouraged to create their own namespaces to avoid naming conflicts.
A final note: Themes/components can also have a `theme` definition in their `config.toml` and similar, which is the "inheritance" part of this commit's title. This is currently not supported by the Hugo theme site. We will have to wait for some "auto dependency" feature to be implemented for that to happen, but this can be a powerful feature if you want to create your own theme-variant based on others.
Fixes#4460Fixes#4450
This commit also has some other nice side-effects:
* The layout logic is unified for all page types, which should make it less surprising
* Page.Render now supports all types
* The legacy "indexes" type is removed from the template lookup order. This is an undocumented type from early Hugo days. This means that having a template in, say, `/layouts/indexes/list.html` will no longer work.
* The theme override logic is improved. As an example, an `index.html` in theme will now wn over a `_default/list.html` in the project, which most will expect.
Fixes#3005Fixes#3245
This applies to both regular templates and shortcodes. So, if the site language is French and the output format is AMP, this is the (start) of the lookup order for the home page:
1. index.fr.amp.html
2. index.amp.html
3. index.fr.html
4. index.html
5. ...
Fixes#3360
This change is motivated by Netlify's `_redirects` files, which is currently not possible to generate with Hugo.
This commit adds a `Delimiter` field to media type, which defaults to ".", but can be blanked out.
Fixes#3614
Before this commit, Hugo used `html/template` for all Go templates.
While this is a fine choice for HTML and maybe also RSS feeds, it is painful for plain text formats such as CSV, JSON etc.
This commit fixes that by using the `IsPlainText` attribute on the output format to decide what to use.
A couple of notes:
* The above requires a nonambiguous template name to type mapping. I.e. `/layouts/_default/list.json` will only work if there is only one JSON output format, `/layouts/_default/list.mytype.json` will always work.
* Ambiguous types will fall back to HTML.
* Partials inherits the text vs HTML identificator of the container template. This also means that plain text templates can only include plain text partials.
* Shortcode templates are, by definition, currently HTML templates only.
Fixes#3221
Before this commit, Hugo used `html/template` for all Go templates.
While this is a fine choice for HTML and maybe also RSS feeds, it is painful for plain text formats such as CSV, JSON etc.
This commit fixes that by using the `IsPlainText` attribute on the output format to decide what to use.
A couple of notes:
* The above requires a nonambiguous template name to type mapping. I.e. `/layouts/_default/list.json` will only work if there is only one JSON output format, `/layouts/_default/list.mytype.json` will always work.
* Ambiguous types will fall back to HTML.
* Partials inherits the text vs HTML identificator of the container template. This also means that plain text templates can only include plain text partials.
* Shortcode templates are, by definition, currently HTML templates only.
Fixes#3221
Using it for list pages doesn't work and has potential weird side-effects.
The user probably meant to range over .Site.ReqularPages, and that is now marked clearly in the log.
