检查变量是否为液体中的字符串或数组类型 [英] Check if variable is type of string or array in liquid

问题描述

在Jekyll中，您可以使用液体模板，而我正在尝试编写一个包含所有链接的导航在网站上.

In Jekyll you can use liquid template and I am trying to write a nav that includes all links in the website.

sitemap:
  home: "/"
  demo:
    right: "/right"
    left: "/left"

我要实现的目标是创建一个包含所有这些链接的侧边栏.但是某些链接在一节中.输出应为以下

What I am trying to achieve is to create a sidebar that icludes all those links. But certains links are under a section. The output should be the following

<nav>
  <ul>
    <li>
      <a href="/">home</a>
    </li>
  </ul>

  <ul>
    <li>demo</li>
    <li>
      <a href="/right">right</a>
    </li>
    <li>
      <a href="/left">left</a>
    </li
  </ul>
</nav>

并非所有部分都必须具有标题.主页链接是独立链接. 演示链接都在演示"部分.

Not all sections must have a title. The home link is a standalone link. The demo links are all in the demo section.

在流动状态下，我可以通过以下方式遍历站点地图:

In liquid I can loop through the sitemap in this way:

{% for nav in site.sitemap %}
<ul>
  <li>{{ nav[0] }}</li>
</ul>
{% endfor %}

这样，液体将打印home和demo.

我需要检查值是字符串还是数组，以便打印数组或单个链接！

What I need is to check if the value is a string or an array in order to print the array or a single link!

是否可以检查液体变量是字符串还是数组? 我在以前链接的文档中找不到它！

Is there a way to check if the liquid variable is a string or an array? I can't find it in the documentation i linked before!

推荐答案

是否可以检查液体变量是字符串还是数组?

Is there a way to check if the liquid variable is a string or an array?

要检查液体变量是字符串还是元素列表(数组或哈希)，请使用数组过滤器

To check if a liquid variable is a string or a list of elements (array or hash), check if it has a first descendant, using the array filter first: {% var.first %} as follow :

{% if var.first %}
  // var is not a string
{% else %}
 // var is a string
{% endif %}

过滤器first返回数组的第一个元素或哈希(如果有)，如果变量为空或元素列表不返回任何内容，并且由于nil是

the filter first return the first element of an array or a hash if it has one, if the variable is empty or not a list of element it return nothing, and since nil is a falsy value in liquid, it works the same as false in the if condition above.

例如:

# var1 = "a"     // string
{% var1.first %} // return:   // nil -> falsy

# var2 = [a,b,c] // array
{% var2.first %} // return: a

# var3 = {k1: a, k2: b, k3: c} // hash
{% var1.first %} // return: k1a

# var4 = {k1, k2, k3: c} // hash, first element is a key without associated value
{% var1.first %} // return: k1

现在我们可以确定元素是否为字符串，我们可以这样做:

Now that we can determine if an element is a string or not, we can do that:

{% for nav in site.sitemap %}
<ul>
  <li>
     {{ nav[0] }} :
        {% if nav[1].first %}
        // loop through: nav[1]
        {% else %}
          {{ nav[1] }}
        {% endif %}        
  </li>
</ul>
{% endfor %}

但是我发现将sitemap用作元素列表(a)更方便*，而不是单个大哈希(实际上是)(b)(请参见 YAML语法)

but I found that's more convenient* to work the sitemap as list of elements (a), instead a single big hash (as it is actually) (b) (cf. YAML syntax)

因此，我通过在每个元素之前添加"- "(破折号和空格)来修改了它的结构:

so I modified it's structure, by adding a "- " (a dash and a space) before each element:

  - home: "/"
  - demo:
    - right: "/right"
    - left: "/left"  

这给了我们 a :

{"home"=>"/"}{"demo"=>[{"right"=>"/right"}, {"left"=>"/left"}]} 

而不是 b :

{"home"=>"/", "demo"=>{"right"=>"/right", "left"=>"/left"}} 

附带说明:您可以将站点地图放在其自己的文件中，该文件位于_data/sitmap.yml中，然后通过site.data.sitemap访问它，而不用在_config.yml中将其定义为属性.保持清洁，使其外观与上面完全相同.

Side Note: you can put the sitemap in it's own file in: _data/sitmap.yml and access it by site.data.sitemap, in lieu of defined it as an attribute in the _config.yml, to keep it cleaner, thereby it'll look exactly as the above.

因为我们将递归地将sitemap本身包括在内(对于每个带有子节点的节点)，所以我们将该模板放置在_includes文件夹中，而不是_layouts

since we'll going to include the sitemap in itself recursively (for each node with children ) we'll put this template in _includes folder and not _layouts

还请注意，Jekyll允许将参数传递给包含对象.但是有一个陷阱，param应该是string，而不是数组或哈希.因此，我们必须从links数组中创建一个字符串.

Notice also that Jekyll allows passing parameters to includes. But there is a catch, the param should be a string not an array, or hash. So, we have to make a string out of the links array.

我们去:

<ul>
  <!--                  links is a param -->
  {%for link in include.links %}

    <li>

      {% for part in link %}
        {{part[0]}} : <!-- part[0] : link name  -->

        {% if part[1].first %} <!-- the element has children -->

          <!-- concatenate jekyll array into a string -->
          {% assign _links = "" | split: "" %}
          {% for _link in part[1] %}
            {% assign _links = _links | push: _link %}
          {% endfor %}
          <!-- pass the string as a param to sitemap, then do the recursive dance -->
          {% include sitemap.html links = _links %}

        {% else %} <!-- no children -->

          {{part[1]}} <!-- part[1] : link url -->

        {% endif %}

      {% endfor%}

    </li>

  {%endfor%}

</ul>

3.使用模板:)

<!-- include and init the param with this ↓, or `site.sitemap` if it's defined in `_config.yml`, or ...  -->
{% include sitemap.html links= site.data.sitemap %}

4.输出

用于:/_data/sitemap.yml:

- home : "/"
- about: "/about"
- archive:
  - left : "/left"
  - right: "/right"
  - other:
    - up: '/other/up'
    - down: '/other/down'

模板产生:

• home:/
• 关于:/about
• 存档:
  • left:/left
  • right:/right
  • 其他:
    • 上:/other/上
    • 下:/other/下
    • home : /
    • about : /about
    • archive :
      • left : /left
      • right : /right
      • other :
        • up : /other/up
        • down : /other/down

        所以您必须将每个链接的part[0]和part[1]放在<a> tag中，例如:

        so you have to put part[0] and part[1] of each link in an <a> tag like:

        <a href="{{part[1]}}"> {{part[0]}} </a>
        

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