How can you determine in a template if a number can be evenly divided by another number?

In website content display, we often encounter situations where we need to adjust the layout or style according to the divisibility of numbers, such as setting different background colors for the odd and even rows of a table, or starting a new row for grouping display every fixed number of contents.In the AnQi CMS template system, implementing such logical judgments is quite direct and efficient.

The AnQi CMS template engine is designed to be very flexible and easy to use, it adopts a syntax structure similar to Django templates, allowing us to access variables through simple references ({{ 变量名 }}）and logical control tags（{% if ... %}/{% for ... %}) to build dynamic content. In addition, it provides a rich set of filters (filters) for processing and transforming variables, including a utility specifically designed to check for divisibility by numbers.

Core solution:divisiblebyFilter

For determining whether a number can be evenly divided by another number, Anqi CMS provides us with a very convenient and powerful tool：divisiblebyFilter. This filter is used to check if a number can be perfectly divided by another number, i.e., the remainder of the division is zero.

Its basic usage is after the numeric variable to be judged, through the pipe character|连接divisiblebyfilter, and use a colon:Specify another number as the divisor. The syntax structure is roughly as follows:

{{ 被检查的数字 | divisibleby: 整除数 }}

When the number being checked can be perfectly divided by the divisor, the filter will returnTrue(true); otherwise, if it cannot be divided, it will returnFalse(false). For example,{{ 21|divisibleby:3 }}will returnTruewhile{{ 22|divisibleby:3 }}it will returnFalse.

Actual application example

MastereddivisiblebyThe use of filters, we can easily implement various logical controls based on the divisibility of numeric integers in the template.

Scenario one: alternating styles of table rows.

This is a very common requirement, by assigning different CSS classes to the odd and even rows of a table, we can improve the readability of the table. When looping through list content, we can useforThe built-in loop offorloop.Countervariable (indicating the current loop index, starting from 1) to judge.

<table>
    <thead>
        <tr>
            <th>序号</th>
            <th>文章标题</th>
            <th>发布日期</th>
        </tr>
    </thead>
    <tbody>
        {% for item in archiveList %}
            <tr class="{% if forloop.Counter|divisibleby:2 %}even-row{% else %}odd-row{% endif %}">
                <td>{{ forloop.Counter }}</td>
                <td>{{ item.Title }}</td>
                <td>{{ stampToDate(item.CreatedTime, "2006-01-02") }}</td>
            </tr>
        {% endfor %}
    </tbody>
</table>

In this piece of code, we check the loop counterforloop.CounterCan be divided by 2. If it can, it means the current is an even line, applyeven-rowclass; if it cannot, it means it is an odd line, applyodd-rowClass.

Scenario two: content list grouping display

Assuming you want to start a new line every 3 articles (div class="row")，to present a three-column layout, making the content more visually tidy. This is very practical in product displays or image-text list pages.

<div class="container">
    {% for item in archiveList %}
        {# 每隔3个项目或在第一个项目时开启新行 #}
        {% if forloop.Counter == 1 or forloop.Counter0|divisibleby:3 %}
            <div class="row">
        {% endif %}

        <div class="col-md-4">
            <div class="article-card">
                <h4>{{ item.Title }}</h4>
                <p>{{ item.Description }}</p>
                <a href="{{ item.Link }}">查看详情</a>
            </div>
        </div>

        {# 每隔3个项目或在最后一个项目时关闭当前行 #}
        {% if forloop.Counter|divisibleby:3 or forloop.Last %}
            </div> {# 关闭 div.row #}
        {% endif %}
    {% endfor %}
</div>

Here we cleverly utilizeforloop.Counter(starting from 1) andforloop.Counter0(Counting from 0) CooperationdivisiblebyFilter to determine when to open a new line and when to close an old line. Whenforloop.Counter0A number divisible by 3 (i.e., the 0th, 3rd, 6th… element), or when it is the first element, we start a newdiv.row. At the same time, whenforloop.CounterThe number is divisible by 3 or it is the last element (forloop.Last), we close the currentdiv.row, to ensure the integrity of the layout.

Scenario three: combined variable dynamic judgment

divisiblebyThe filter can not only be used for hard-coded numbers, but it also works well with variables in the template.For example, you can obtain the number of articles displayed per row from the system settings and use it as the divisor.

{% set articles_per_row = system.articles_per_row %} {# 假设系统设置中有此变量，值为3或4等 #}

<div class="container">
    {% for item in archiveList %}
        {% if forloop.Counter == 1 or forloop.Counter0|divisibleby:articles_per_row %}
            <div class="row">
        {% endif %}
        <div class="col-md-{{ 12|divisibleby:articles_per_row }}"> {# 动态计算列宽 #}
            <div class="product-item">
                <h3>{{ item.Title }}</h3>
                <img src="{{ item.Thumb }}" alt="{{ item.Title }}">
            </div>
        </div>
        {% if forloop.Counter|divisibleby:articles_per_row or forloop.Last %}
            </div>
        {% endif %}
    {% endfor %}
</div>

In this example,articles_per_rowIs a variable obtained from the system configuration, which makes the grouping logic more flexible and controllable, without modifying the template code you can adjust the layout. At the same time, we also demonstrated12|divisibleby:articles_per_rowThis usage, but pay attentiondivisiblebyThe filter itself returns a boolean value, here you should use ordinary division, for example12 / articles_per_rowTo dynamically calculate the column width. Ifarticles_per_rowIs 3, then the column width is 4.

Cautionary notes and **practice

While usingdivisiblebyWhen filtering, there are several points to note:

1. Input type:Ensure that the parameter passed todivisiblebyThe number of the filter is a valid numeric type. Normally, template variables will be processed correctly, but if an unexpected situation occurs, please check the output value of the variable.
2. Readability:Even though template code can be written compactly, proper indentation and comments are still good practices for team collaboration and future maintenance.
3. Combined with other logic: divisiblebyThe filter returns a boolean value, which means it can be directly embedded into{% if ... %}tags, and can also be combined with other logical operators (such asand/or/not) to build more complex conditional judgments.
4. Use loop variables wisely: forLoop