AnQiCMS 模板 `if` 标签如何实现多条件逻辑判断（或/or、与/and、非/not）？

In AnQiCMS template development, mastering conditional logic judgment is the key to building dynamic and intelligent web pages. Wherein,ifLabel as the core of content display, not only supports simple boolean judgment, but also can flexibly realize logical combination of multiple conditions, such as “and”&&）、“or”||）and“not”!）等。Understand and make good use of these logical operators, which can help us finely control the display and hiding of template elements, thereby creating a more interactive and customizable user experience.

Basic condition judgment:if/elifWithelse

Before delving into multi-condition logic, let's review firstif标签的基础用法。AnQiCMS 的模板语法类似于 Django 风格，通过{% if 条件 %}and{% endif %}来包裹需要条件性显示的内容。

The simplest form is to check if a variable exists or is true:

{% if archive.Thumb %}
    <img src="{{ archive.Thumb }}" alt="{{ archive.Title }}" />
{% endif %}

Here,{% if archive.Thumb %}will checkarchive.ThumbCheck if the variable has a value.archive.ThumbNot empty, notnilorfalse, then the image will be displayed.

When you need to handle multiple mutually exclusive conditions, you can useelif(else if abbreviation) andelsetags, which will be judged in order. Once a condition is met, subsequentelifandelseblocks will be ignored:

{% if archive.Status == 1 %}
    <p>文章已发布</p>
{% elif archive.Status == 0 %}
    <p>文章审核中</p>
{% else %}
    <p>文章状态未知</p>
{% endif %}

This structure allows you to display different content based on different data states, greatly enhancing the adaptability of the template.

Taming complex logic:&&/||and!application

When a single condition is not sufficient to express your logic, multi-condition logical judgment becomes particularly important. AnQiCMS'sifLabel supports standard logical operators, allowing you to combine into more complex judgment expressions.

Logical "AND"&&(AND)

Logical "AND" operator&&Used to require that all conditions must be true at the same time for the content to be displayed. This is very useful in scenarios where you need to strictly meet multiple standards to trigger a behavior.

For example, you may want to display a special "hot" badge only when the document is marked as "top story" (flag='h') and its views (Views) exceed 1000.

{% if archive.Flag == 'h' && archive.Views > 1000 %}
    <span class="badge hot-item">热门头条</span>
{% endif %}

Ifarchive.FlagNot 'h', orarchive.ViewsIf it is not greater than 1000, then this badge will not be displayed. You can also useandinstead&&, the effect is the same.

Logical 'or':||(OR)

Logical "OR" operator||This means that the content will be displayed if any of the multiple conditions are true. This applies to situations where multiple paths or standards can lead to the same result.

like, you want the navigation item to be highlighted in the navigation bar of the website when the current category is "company news" (CategoryId == 1) or "industry dynamics" (CategoryId == 5):

<a href="{{ item.Link }}" {% if item.CategoryId == 1 || item.CategoryId == 5 %}class="active-nav"{% endif %}>
    {{ item.Title }}
</a>

as long asitem.CategoryIdequal to 1 or 5,active-navthe class will be added. You can also useorinstead||.

logical NOT:!(NOT)

logical NOT operator!Used to reverse the truth value of a condition. If a condition is true,!it will become false; if it is false, it will become true. This is very convenient for determining that a certain condition does not hold.

For example, you may wish to display a default placeholder image when there is no thumbnail in the document (Thumbis empty ornil)，display a default placeholder image:

{% if not archive.Thumb %}
    <img src="/static/images/default-thumb.png" alt="无图片" />
{% else %}
    <img src="{{ archive.Thumb }}" alt="{{ archive.Title }}" />
{% endif %}

Here,not archive.Thumbwillarchive.Thumbis empty orfalsereturns true. You can also use!insteadnot.

Combining use, flexible to deal with complex scenarios

The real strength of multi-condition logical judgments lies in their ability to be combined. Through brackets()To clarify the order of operations, you can construct highly complex logical expressions.

Suppose you have a product list and want to highlight items that meet any of the following conditions:

1. Stock is sufficient (Stock > 0）and price is favorable（Price < 100).
2. is marked as 'Special Price'(Flag == 'a').

{% if (product.Stock > 0 && product.Price < 100) || product.Flag == 'a' %}
    <span class="product-highlight">超值推荐！</span>
{% endif %}

This example shows how to nest&&and||to achieve more fine-grained control. Only when inventory is sufficientandprice is favorable,orWhen the product is on sale, the "Super Value Recommendation" prompt will appear.

In addition to directly comparing variables, you can also inifUsing various filters to assist in judgment. For example, to determine if a title string contains a certain keyword:

{% if archive.Title|contain:"AnQiCMS" %}
    <p>这篇是关于 AnQiCMS 的文章！</p>
{% endif %}

Or to judge the length of a list:

{% if archiveList|length_is:0 %}
    <p>暂无相关文章。</p>
{% endif %}

Such a combination allows your AnQiCMS template to have high flexibility and expressiveness, which can intelligently present the most appropriate content according to the endless changes of website data.

Summary

In the AnQiCMS templateifLabels are more than just simple “yes” or “no” judgments. Throughelifandelseprovide multiple path choices, and through&&/||and!These logical operators allow you to cleverly combine multiple conditions to meet various complex content display requirements.Remember to use parentheses to manage the priority of expressions, and combine various built-in filters, your template will be able to respond more intelligently and dynamically to user and data changes.

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Common Questions (FAQ)

Q1: Inifin the tag,&&andand/||andorWhat's the difference?A1: In AnQiCMS template engine,&&andand/||andorAll are equivalent logical operators, and they function identically. You can choose to use any one of them based on personal preference or coding style. For example,{% if condition1 && condition2 %}and{% if condition1 and condition2 %}they will produce the same effect.

Q2: How to determine if a variable is empty (for example, a string is empty, or a list has no elements)?A2: AnQiCMS templatesifThe label is very smart in determining whether a variable exists or is not empty. You can use it directly.{% if 变量名 %}to judge whether the variable has a non-empty value. For example,{% if archive.Title %}willTitlea string is not empty, it is true.{% if archives %}willarchives列表或数组有元素时为真。相反，要判断变量为空，则可以使用{% if not 变量名 %}.

Q3: If myif条件非常复杂，有很多&&and||组合在一起，有什么建议吗？A3: When the conditional logic becomes very complex, it is recommended that you use parentheses()To clarify the precedence of operators, this can greatly enhance code readability and avoid issues caused by incorrect understanding of precedence. Additionally, if there are too many conditional branches, consider splitting some logic into differentif-elif-elseIn the structure, or in the complex logic processing part on the backend, pass a simpler boolean variable to the front-end template. Keep the template logic clear