What content will the `bannerList` tag return if there is no home page Banner configured on the backend?

As an experienced website operation expert, I am well aware that even the slightest details of each CMS tag can affect the display effect and operation strategy of a website. Today, let's talk about a commonly used but potentially confusing tag in AnQiCMS (AnQiCMS) -bannerListEspecially when no homepage banner is configured on the backend, what content will it return, and how should we elegantly handle this situation in the template.

Deep understandingbannerListThe essence of tags

In the Anqi CMS,bannerListLabels are specifically used to obtain the data for the website homepage carousel (Banner). According to the documents we have reviewed, it is described as：“Used to get the home page Banner listbanners is an array object, so it needs to usefora loop to output.bannerList标签预期会返回一个包含零个或多个Banner项的集合。

每一个通过bannerList获取到的Banner项（我们通常在forloop) contains a very useful property:itemAll contain structured data, such asId/Logo(Image address,)Link(Link address,)Description(Introduction) andAlt(Image Alt attribute) and these fields together constitute all the information required to display a Banner on the front end.

When the background is empty:bannerListActual return

Then, if there is no Banner configured in the home page Banner management area of the website backend,bannerListwhat content will the tag return? The answer is:It will return an empty array object (Empty Array Object).

This is not an error, nornullorundefined.It is a legal set of array collections, but it does not contain any elements.length) is zero.

This means that when your template uses{% bannerList banners %}When retrieving data, even if there is no backend configuration,bannersThis variable still exists; it is just a collection without any Banner items. When you try to perform on this emptybannerscollection.forThe loop body will not be executed during the loop.

Elegant handling in the template:for...empty...endfor

UnderstoodbannerListHow to elegantly handle the characteristics of an empty array in front-end templates becomes very important. Anqi CMS (based on Django template engine syntax) provides a very convenient control structure for this scenario -for...empty...endforLoop.

for...empty...endforLoops allow you to define a code block that will only be executed when the collection is empty.Here, you can display a friendly prompt, default image, or trigger other content display logic when there is no Banner data, rather than leaving a blank area on the page or causing layout issues.

The following is a classic template code example, demonstrating how to usefor...empty...endforto handlebannerListthe case of returning an empty array:

{% bannerList banners %}
    {% for item in banners %}
    <a href="{{item.Link}}" target="_blank">
        <img src="{{item.Logo}}" alt="{{item.Alt}}" />
        <h5>{{item.Title}}</h5>
    </a>
    {% empty %}
    {# 当后台没有配置任何Banner时，这里的内容会被执行 #}
    <div class="no-banner-placeholder">
        <img src="/static/images/default-banner.webp" alt="暂无Banner，请在后台配置" />
        <p>抱歉，当前暂无首页轮播图，敬请期待！</p>
        <p><a href="/contact">联系我们了解更多</a></p>
    </div>
    {% endfor %}
{% endbannerList %}

In this code block:

  1. {% bannerList banners %}Try to get the home page banner list.
  2. {% for item in banners %}Start traversingbannersarray.
  3. IfbannersIf there is content in the array,<a>...</a>The code within the tag will be executed once for each Banner item.
  4. IfbannersThe array is empty (i.e., no Banners are configured on the backend), then{% for ... %}and{% empty %}The code between them will not be executed, instead, it will execute{% empty %}and{% endfor %}The code between them. Here we place a default placeholder image and prompt text.

Inspiration for practical application and content operation

This approach is of great significance to content operations:

  • Enhance user experience:Avoid the page from appearing空洞 or layout errors due to missing content, bringing an unpleasant experience to the user.Even without real-time content, the interface's integrity and aesthetics can be maintained by default placeholders.
  • Guide user behavior:When there is no active banner, you can use{% empty %}To display a prompt for uploading a "Banner", a link to view the latest products, or a fixed marketing entry, directing users to other valuable pages.
  • Simplifying development and maintenance:The template developer does not need to write extra codeif banners.length > 0This kind of judgment logic,for...empty...endforThe structure itself includes this kind of judgment, making the code more concise, readable, and maintainable.

In short, the Anqi CMS isbannerListThe label will intelligently return an empty array object when no data is configured, which provides us with the opportunity to utilizefor...empty...endforAn opportunity to handle structure flexibly and elegantly. Mastering this will enable better optimization of the website's front-end display, enhance user experience, and provide more possibilities for content operation.

Common Questions (FAQ)

1. If only one home page Banner is configured on the backend,bannerListwhat will the tag return? bannerListthe tag will still return an array object, but this array only contains one Banner item. YourforThe loop will execute normally once, displaying this unique Banner.{% empty %}The block will not be triggered in this case.

2. Besidesfor...empty...endforThere are other ways to judgebannerListIs it empty?Of course you can. You can useifTag combinationlengthfilters to determine, such as{% if banners|length > 0 %}to check if the array has elements. However,for...empty...endforThis is the recommended and more concise way by Anqian CMS (and Django template engine) because it integrates the loop and null value judgment.

3.bannerListWhat is the difference between the "Banner image" configured on the category detail page?They serve different purposes and page ranges.bannerListTags are specifically used for acquisitionHome PageThe carousel data, whose configuration is usually in the global Banner management module of the website. The 'Banner image' on the category detail page is configured under a specific category and will only be displayed on that category page, usually throughcategoryDetailLabel (for example){% categoryDetail with name="Images" %}To get, used to display unique visual elements of this category.