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diff --git a/exampleSite/content/post/go-is-for-lovers.md b/exampleSite/content/post/go-is-for-lovers.md deleted file mode 100644 index 138ca25..0000000 --- a/exampleSite/content/post/go-is-for-lovers.md +++ /dev/null @@ -1,335 +0,0 @@ -+++ -title = "Go is for lovers" -date = "2015-09-17T13:47:08+02:00" -tags = ["go"] -categories = ["programming"] -menu = "" -banner = "banners/placeholder.png" -+++ - -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 that 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] -provide more details. - -## 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 ship 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:** - - {{ add 1 2 }} - -## 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 "chrome/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 }} - - -## Context (aka. 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 | lower }}">{{ . }}</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 (eg, `config.yaml`) you can define site -parameters, which are values which will be available to you in chrome. - -For instance, you might declare: - -```yaml -params: - CopyrightHTML: "Copyright © 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/> |