Understanding data structures is the foundation of efficient work in template development for AnQi CMS. Especially when we need to debug complex Go language struct data, if we only use the conventional variable output method{{ 变量名 }}often can only see simple values, even memory addresses, which is not very helpful for understanding the overall picture of the data and locating problems. Fortunately, AnQi CMS provides powerfulstringformatFilter, in conjunction with Go language,%#vformats verbs, which can help us clearly output struct data in a debugging-friendly manner.

Why do we need debugging-friendly output?

Imagine that you are building an article detail page that needs to display all the information about the document, including custom fields, category details, etc.The AnQi CMS backend passes this data as a Go language struct to the template.archiveWhat fields does the variable contain, or what is the specific type of a certain field, can be written directly in the template{{ archive }}It may only output&{...}Such brief information, which does not directly tell youarchiveWhat are the available field names and their values inside the structure?

At this moment, if you can see output formats similar to Go language source code snippets, including struct types, field names, and corresponding values, it will undoubtedly greatly improve debugging efficiency.

KnowstringformatFilter

stringformatThe filter is a very practical tool in the AnQi CMS template engine, its function is similar to that in the standard library of Go language.fmt.Sprintf()Function.This means you can use various formatting verbs in Go to control the output format.stringformatThey can all respond flexibly.

For example, if you want to output a floating-point number with two decimal places, you can use it like this:{{ 3.141592653|stringformat:"%.2f" }}, the result will be3.14.

%#vThe 'secret weapon' of debugging:

Among the many formatting verbs,%#vIt is the 'secret weapon' when we debug Go struct data. When you usestringformatFilter is related to%#vWhen used together, it outputs the value represented in Go language syntax, including the type name of the struct and the names and corresponding values of each field.This is like directly viewing the Go language code definition of the structure and the actual state after filling in the data, which is very helpful for understanding the data model.

It can help you:

  • View the complete struct definition:Understand all fields and their data types included in the structure.
  • Verify data accuracy:Confirm whether each field is filled with the correct value as expected.
  • Identify potential issues:Quickly identify which fields are empty or which fields do not match the expected data types.

Practice in the Anqi CMS template.

Now, let's look at several examples of how to utilizestringformatand%#vto debug Go struct data specifically.

To make the debug output clearer and more readable, we usually wrap it in<pre>tags, which can preserve the original format and indentation.

1. Debug a single document'sarchiveentire structure:

Assume you are developing a detail page for an article ({模型table}/detail.html),archiveVariables usually represent the detailed data of the current article. To view its full structure, you can write it like this: 

<p>当前文档的完整结构：</p>
<pre>{{ archive|stringformat:"%#v" }}</pre>

This code will output content similar to the following format (the specific content depends on your document data and model definition):

&models.Archive{Id:123, Title:"安企CMS模板调试指南", SeoTitle:"", Link:"/article/123.html", Keywords:"安企CMS,模板调试,Go结构体", Description:"如何在安企CMS模板中调试Go结构体...", Content:"<p>正文内容...</p>", ModuleId:1, CategoryId:45, ...}

From the output, you can clearly seearchiveis amodels.ArchiveA structure of types, and lists theId/Title/SeoTitlenames of all fields and their current values.

2. Debug nested structures (such as)archive.Category):

The document structure often contains nested structures, such asarchive.CategoryRepresents the detailed information of the category to which the current document belongs. The usage for debugging this nested structure is also similar:

<p>当前文档所属分类的完整结构：</p>
<pre>{{ archive.Category|stringformat:"%#v" }}</pre>

The output may be as follows:

&models.Category{Id:45, Title:"开发教程", Link:"/category/45.html", Description:"安企CMS开发教程分类", ParentId:0, Logo:"https://en.anqicms.com/uploads/...", Thumb:"https://en.anqicms.com/uploads/...", ...}

This allows you toarchive.Categoryhave a clear view of the data included.

3. Debug the structure of list items in a loop:

When you usearchiveListand obtain the document list with tags such as:forDebug the structure of each list item while iterating in the loop:

{% archiveList archives with type="list" limit="2" %}
    {% for item in archives %}
        <p>列表第 {{ forloop.Counter }} 个文档的完整结构：</p>
        <pre>{{ item|stringformat:"%#v" }}</pre>
    {% endfor %}
{% endarchiveList %}

So, you can check each item in the list one by one.itemThe specific data.

4. CombinesetLabel temporary debugging:

Sometimes, you might want to debug an intermediate variable generated through complex logic, or simply want to temporarily save a struct for inspection, you can usesetTags:

{% set tempVariable = someComplexFunctionOutput %} {# 假设这里得到了一个结构体 #}
<p>临时变量的完整结构：</p>
<pre>{{ tempVariable|stringformat:"%#v" }}</pre>

Important reminder:After debugging is complete, please be sure to remove these debug outputs from the production environment code to avoid leaking sensitive information, affecting page performance, and search engine crawling.These debugging tools are mainly used in the development and testing stages.

Summary

stringformata filter combined with Go language's%#vFormat verbs, it is an invaluable debugging tool in the development of AnQi CMS templates.It converts abstract data from templates into clear, readable Go language struct representations, helping you to understand data flow more deeply and quickly locate and solve problems in template rendering.Mastering this skill will make your secure CMS template development experience smoother and more efficient.

Common Questions (FAQ)

1.stringformatFilterer does not%#vWhat else can you do? stringformatFilterer supports Go languagefmt.Sprintf()All formatting verbs of functions. Besides debugging structures%#v, you can also use%v(Default format of the value),%+v(Display the field name of the structure),%T(Display the type of the value),%d(Integer),%.2f(Floating point number, rounded to two decimal places),%s(string) and so on. For example,{{ someInt|stringformat:"当前数字是 %d" }}You can embed numbers into custom strings.

2. Why do I directly print{{ archive }}but do not see the complete structure, only displaying&{...}?This is because the template engine, by default, usually only outputs a brief representation (such as memory address or type name) of complex Go struct or pointer types, rather than detailed internal fields.This design is to maintain the simplicity of template output and prevent unnecessary verbose information.%#vFormatting verbs are used to explicitly indicate to the template engine the form in which the struct should be outputted in Go language syntax, thereby providing detailed debugging information.

3. Will retaining these debug outputs in a production environment affect website performance and SEO?Yes, debug output information usually contains a large amount of technical details and unformatted text, and if it is retained in a production environment, it may cause the following negative impacts:

  • Performance:Each page load needs to generate these additional debugging information, which may increase the CPU and memory overhead of the server, thereby reducing the page loading speed.
  • SEO:Search engines may treat this non-user visible debug information as irrelevant content during the crawling and indexing of page content, which may affect the identification of the page's theme, even leading to judgments of 'insufficient content' or 'low quality', thereby having an adverse effect on SEO rankings.
  • Security:Debug output may inadvertently expose sensitive information about the system's internal structure, such as database structure, file paths, etc., which may provide an opportunity for potential attackers.

Therefore, debug-friendly output is only recommended to be used during development and testing stages, and it must be removed or commented out before deploying to the production environment.