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+---
+aliases:
+- /layout/go-templates/
+- /layouts/go-templates/
+date: 2013-07-01
+menu:
+  main:
+    parent: layout
+next: /templates/functions
+prev: /templates/overview
+title: Go Template Primer
+weight: 15
+---
+
+Hugo uses the excellent [Go][] [html/template][gohtmltemplate] library for
+its template engine. It is an extremely lightweight engine that provides a very
+small amount of logic. In our experience it is just the right amount of
+logic to be able to create a good static website. If you have used other
+template systems from different languages or frameworks, you will find a lot of
+similarities in Go templates.
+
+This document is a brief primer on using Go templates. The [Go docs][gohtmltemplate]
+go into more depth and cover features that aren't mentioned here.
+
+## Introduction to Go Templates
+
+Go templates provide an extremely simple template language. It adheres to the
+belief that only the most basic of logic belongs in the template or view layer.
+One consequence of this simplicity is that Go templates parse very quickly.
+
+A unique characteristic of Go templates is they are content aware. Variables and
+content will be sanitized depending on the context of where they are used. More
+details can be found in the [Go docs][gohtmltemplate].
+
+## Basic Syntax
+
+Go lang templates are HTML files with the addition of variables and
+functions.
+
+**Go variables and functions are accessible within {{ }}**
+
+Accessing a predefined variable "foo":
+
+    {{ foo }}
+
+**Parameters are separated using spaces**
+
+Calling the `add` function with input of 1, 2:
+
+    {{ add 1 2 }}
+
+**Methods and fields are accessed via dot notation**
+
+Accessing the Page Parameter "bar"
+
+    {{ .Params.bar }}
+
+**Parentheses can be used to group items together**
+
+    {{ if or (isset .Params "alt") (isset .Params "caption") }} Caption {{ end }}
+
+
+## Variables
+
+Each Go template has a struct (object) made available to it. In Hugo, each
+template is passed either a page or a node struct depending on which type of
+page you are rendering. More details are available on the
+[variables](/layout/variables) page.
+
+A variable is accessed by referencing the variable name.
+
+    <title>{{ .Title }}</title>
+
+Variables can also be defined and referenced.
+
+    {{ $address := "123 Main St."}}
+    {{ $address }}
+
+
+## Functions
+
+Go template ships with a few functions which provide basic functionality. The Go
+template system also provides a mechanism for applications to extend the
+available functions with their own. [Hugo template
+functions](/layout/functions) provide some additional functionality we believe
+are useful for building websites. Functions are called by using their name
+followed by the required parameters separated by spaces. Template
+functions cannot be added without recompiling Hugo.
+
+**Example 1: Adding numbers**
+
+    {{ add 1 2 }}
+
+**Example 2: Comparing numbers**
+
+    {{ lt 1 2 }}
+
+(There are more boolean operators, detailed in the
+[template documentation](http://golang.org/pkg/text/template/#hdr-Functions).)
+
+## Includes
+
+When including another template, you will pass to it the data it will be
+able to access. To pass along the current context, please remember to
+include a trailing dot. The templates location will always be starting at
+the /layout/ directory within Hugo.
+
+**Example:**
+
+    {{ template "partials/header.html" . }}
+
+And, starting with Hugo v0.12, you may also use the `partial` call
+for [partial templates](/templates/partials/):
+
+    {{ partial "header.html" . }}
+
+
+## Logic
+
+Go templates provide the most basic iteration and conditional logic.
+
+### Iteration
+
+Just like in Go, the Go templates make heavy use of `range` to iterate over
+a map, array or slice. The following are different examples of how to use
+range.
+
+**Example 1: Using Context**
+
+    {{ range array }}
+        {{ . }}
+    {{ end }}
+
+**Example 2: Declaring value variable name**
+
+    {{range $element := array}}
+        {{ $element }}
+    {{ end }}
+
+**Example 2: Declaring key and value variable name**
+
+    {{range $index, $element := array}}
+        {{ $index }}
+        {{ $element }}
+    {{ end }}
+
+### Conditionals
+
+`if`, `else`, `with`, `or` & `and` provide the framework for handling conditional
+logic in Go Templates. Like `range`, each statement is closed with `end`.
+
+Go Templates treat the following values as false:
+
+* false
+* 0
+* any array, slice, map, or string of length zero
+
+**Example 1: `if`**
+
+    {{ if isset .Params "title" }}<h4>{{ index .Params "title" }}</h4>{{ end }}
+
+**Example 2: `if` … `else`**
+
+    {{ if isset .Params "alt" }}
+        {{ index .Params "alt" }}
+    {{else}}
+        {{ index .Params "caption" }}
+    {{ end }}
+
+**Example 3: `and` & `or`**
+
+    {{ if and (or (isset .Params "title") (isset .Params "caption")) (isset .Params "attr")}}
+
+**Example 4: `with`**
+
+An alternative way of writing "`if`" and then referencing the same value
+is to use "`with`" instead. `with` rebinds the context `.` within its scope,
+and skips the block if the variable is absent.
+
+The first example above could be simplified as:
+
+    {{ with .Params.title }}<h4>{{ . }}</h4>{{ end }}
+
+**Example 5: `if` … `else if`**
+
+    {{ if isset .Params "alt" }}
+        {{ index .Params "alt" }}
+    {{ else if isset .Params "caption" }}
+        {{ index .Params "caption" }}
+    {{ end }}
+
+## Pipes
+
+One of the most powerful components of Go templates is the ability to
+stack actions one after another. This is done by using pipes. Borrowed
+from Unix pipes, the concept is simple, each pipeline's output becomes the
+input of the following pipe.
+
+Because of the very simple syntax of Go templates, the pipe is essential
+to being able to chain together function calls. One limitation of the
+pipes is that they only can work with a single value and that value
+becomes the last parameter of the next pipeline.
+
+A few simple examples should help convey how to use the pipe.
+
+**Example 1:**
+
+    {{ if eq 1 1 }} Same {{ end }}
+
+is the same as
+
+    {{ eq 1 1 | if }} Same {{ end }}
+
+It does look odd to place the `if` at the end, but it does provide a good
+illustration of how to use the pipes.
+
+**Example 2:**
+
+    {{ index .Params "disqus_url" | html }}
+
+Access the page parameter called "disqus_url" and escape the HTML.
+
+**Example 3:**
+
+    {{ if or (or (isset .Params "title") (isset .Params "caption")) (isset .Params "attr")}}
+    Stuff Here
+    {{ end }}
+
+Could be rewritten as
+
+    {{  isset .Params "caption" | or isset .Params "title" | or isset .Params "attr" | if }}
+    Stuff Here
+    {{ end }}
+
+### Internet Explorer conditional comments using Pipes
+
+By default, Go Templates remove HTML comments from output. This has the unfortunate side effect of removing Internet Explorer conditional comments. As a workaround, use something like this:
+
+    {{ "<!--[if lt IE 9]>" | safeHtml }}
+      <script src="html5shiv.js"></script>
+    {{ "<![endif]-->" | safeHtml }}
+
+## Context (a.k.a. the dot)
+
+The most easily overlooked concept to understand about Go templates is that `{{ . }}`
+always refers to the current context. In the top level of your template this
+will be the data set made available to it. Inside of a iteration it will have
+the value of the current item. When inside of a loop the context has changed.
+`.` will no longer refer to the data available to the entire page. If you need
+to
+access this from within the loop, you will likely want to set it to a variable
+instead of depending on the context.
+
+**Example:**
+
+      {{ $title := .Site.Title }}
+      {{ range .Params.tags }}
+        <li> <a href="{{ $baseurl }}/tags/{{ . | urlize }}">{{ . }}</a> - {{ $title }} </li>
+      {{ end }}
+
+Notice how once we have entered the loop the value of `{{ . }}` has changed. We
+have defined a variable outside of the loop so we have access to it from within
+the loop.
+
+# Hugo Parameters
+
+Hugo provides the option of passing values to the template language
+through the site configuration (for sitewide values), or through the meta
+data of each specific piece of content. You can define any values of any
+type (supported by your front matter/config format) and use them however
+you want to inside of your templates.
+
+
+## Using Content (page) Parameters
+
+In each piece of content, you can provide variables to be used by the
+templates. This happens in the [front matter](/content/front-matter).
+
+An example of this is used in this documentation site. Most of the pages
+benefit from having the table of contents provided. Sometimes the TOC just
+doesn't make a lot of sense. We've defined a variable in our front matter
+of some pages to turn off the TOC from being displayed.
+
+Here is the example front matter:
+
+```
+---
+title: "Permalinks"
+date: "2013-11-18"
+aliases:
+  - "/doc/permalinks/"
+groups: ["extras"]
+groups_weight: 30
+notoc: true
+---
+```
+
+Here is the corresponding code inside of the template:
+
+      {{ if not .Params.notoc }}
+        <div id="toc" class="well col-md-4 col-sm-6">
+        {{ .TableOfContents }}
+        </div>
+      {{ end }}
+
+
+
+## Using Site (config) Parameters
+In your top-level configuration file (e.g., `config.yaml`) you can define site
+parameters, which are values which will be available to you in partials.
+
+For instance, you might declare:
+
+```yaml
+params:
+  CopyrightHTML: "Copyright &#xA9; 2013 John Doe. All Rights Reserved."
+  TwitterUser: "spf13"
+  SidebarRecentLimit: 5
+```
+
+Within a footer layout, you might then declare a `<footer>` which is only
+provided if the `CopyrightHTML` parameter is provided, and if it is given,
+you would declare it to be HTML-safe, so that the HTML entity is not escaped
+again.  This would let you easily update just your top-level config file each
+January 1st, instead of hunting through your templates.
+
+```
+{{if .Site.Params.CopyrightHTML}}<footer>
+<div class="text-center">{{.Site.Params.CopyrightHTML | safeHtml}}</div>
+</footer>{{end}}
+```
+
+An alternative way of writing the "`if`" and then referencing the same value
+is to use "`with`" instead. With rebinds the context `.` within its scope,
+and skips the block if the variable is absent:
+
+```
+{{with .Site.Params.TwitterUser}}<span class="twitter">
+<a href="https://twitter.com/{{.}}" rel="author">
+<img src="/images/twitter.png" width="48" height="48" title="Twitter: {{.}}"
+ alt="Twitter"></a>
+</span>{{end}}
+```
+
+Finally, if you want to pull "magic constants" out of your layouts, you can do
+so, such as in this example:
+
+```
+<nav class="recent">
+  <h1>Recent Posts</h1>
+  <ul>{{range first .Site.Params.SidebarRecentLimit .Site.Recent}}
+    <li><a href="{{.RelPermalink}}">{{.Title}}</a></li>
+  {{end}}</ul>
+</nav>
+```
+
+
+[go]: http://golang.org/
+[gohtmltemplate]: http://golang.org/pkg/html/template/
+
+# Template example: Show only upcoming events
+
+Go allows you to do more than what's shown here.  Using Hugo's
+[`where`](/templates/functions/#toc_4) function and Go built-ins, we can list
+only the items from `content/events/` whose date (set in the front matter) is in
+the future:
+
+    <h4>Upcoming Events</h4>
+    <ul class="upcoming-events">
+    {{ range where .Data.Pages.ByDate "Section" "events" }}
+      {{ if ge .Date.Unix .Now.Unix }}
+        <li><span class="event-type">{{ .Type | title }} —</span>
+          {{ .Title }}
+          on <span class="event-date">
+          {{ .Date.Format "2 January at 3:04pm" }}</span>
+          at {{ .Params.place }}
+        </li>
+      {{ end }}
+    {{ end }}