# PHP phalcon volt

***volt 的代碼是由 PHP 和 HTML 構成***

## {{ ... }} Assignments賦值

{% set fruits = ['Apple', 'Banana', 'Orange'], name = robot.name %}
{% set price += 100.00 %}
{% set age *= 5 %}

## {{ ... }} Variables變數

{{ fruits[2] }}

{{ post.title }} {# for $post->title #}
{{ post['title'] }} {# for $post['title'] #}

## {{ ...\|... }} Filters過濾器

{{ post.title|e }}
{{ post.content|striptags }}
{{ name|capitalize|trim }}

| Filter | Description | Example |
| -------- | -------- | -------- |
| abs | 轉成正數 | |
| capitalize | 首字母大寫 | |
| default | 預設內容 | \{\{ num \| default('1') \}\} |
| format | 格式化 | {{ "My real name is %s"\|format(fruits[2]\|capitalize) \}\} |
| e or escape | 忽略tag(包含tags的字串) | {{ "\<h1>Hello\<h1>"\|e \}\} → \<h1>Hello\<h1> |
| trim | 移除頭尾空白 | {{ " hello "\|trim \}\} |
| striptags | 移除HTML之tags(剩內容) | {{ "\<h1>Hello\<h1>"\|striptags \}\} → Hello |
| length | 長度 | {{ "robots"\|length \}\}<br/>{{[1,2,3] \|length\}\} |
| keys | 回傳keys的array | {% set keys = ['first': 1, 'second': 2, 'third': 3]\|keys %\} |
| join | 隔開陣列中每個元素的字串 | {% set joined = "a".."z"\|join(",") %\} |
| json_encode | 對變數進行 JSON 編碼 | {% set encoded = robots\|json_encode %\} |
| json_decode | 對 JSON 格式的字串進行編碼 | {% set decoded = '{"one":1,"two":2,"three":3}'\|json_decode %\} |

## {% ... %} 循環語句或判斷

{% for index in 0..fruits|length %}
    {% if fruits[index] is defined %}
        {{ 'Name: ' ~ fruits[index] }}  
    {% endif %}
{% endfor %}

## {# ... #} 注釋

{# {% fruits[2] %} #}

## Loop Context 循環上下文

{% for robot in robots %}
    {% if loop.first %}
        <table>
            <tr>
                <th>#</th>
                <th>Id</th>
                <th>Name</th>
            </tr>
    {% endif %}
            <tr>
                <td>{{ loop.index }}</td>
                <td>{{ robot.id }}</td>
                <td>{{ robot.name }}</td>
            </tr>
    {% if loop.last %}
        </table>
    {% endif %}
{% endfor %}

| Variable | Description |
| -------- | -------- |
| loop.index | 目前迴圈的索引(從1開始) |
| loop.index0 | 目前迴圈的索引(從0開始) |
| loop.revindex | 目前迴圈剩餘次數(從1開始) |
| loop.revindex0 | 目前迴圈剩餘次數(從0開始) |
| loop.first | 若是迴圈第一個則回傳 true |
| loop.last | 若是迴圈最後一個則回傳 true |
| loop.length | 總迴圈長度 |

## Other Operators 其他
| Operator | Description |
| -------- | -------- |
| ~ | 結合運算符 {{ 'hello ' ~ 'world' }} → hello world |
| .. | Creates a range {{ 'a'..'z' }} {{ 1..10 }} |
| is | Same as == (equals) |
| in | if 'a' in 'abc' |
| is not | Same as != (not equals) |
| 'a' ? 'b' : 'c' | 三元運算 |

## Tests 測試運算

{% set robots = ['1': 'Voltron', '2': 'Astro Boy', '3': 'Terminator', '4': 'C3PO'] %}

{% for position, name in robots %}
    {% if position is odd %}
        {{ name }}
    {% endif %}
{% endfor %}

| Test | Description |
| -------- | -------- |
| defined | Checks if a variable is defined (isset()) |
| divisibleby | Checks if a value is divisible by other value |
| empty | Checks if a variable is empty |
| even | Checks if a numeric value is even |
| odd | Checks if a numeric value is odd |
| iterable | Checks if a value is iterable. Can be traversed by a ‘for’ statement<br/>{% set robots = [1: 'Voltron', 2: 'Astroy Boy'] %}<br/>{% if robots is iterable %}<br/>{% for robot in robots %}<br/>{% endfor %}<br/>{% endif %} |
| sameas | Checks if a value is identical to other value <br/> {% set world = 'hello' %} <br/>{% if world is sameas('hello') %} |
| numeric | Checks if value is numeric |
| scalar | Checks if value is scalar (not an array or object) |
| type | Checks if a value is of the specified type <br/> {% if external is type('boolean') %} |

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### 來源
1. https://docs.phalcon.io/3.4/en/volt#introduction
2. http://www.iphalcon.cn/reference/volt.html