When using the AQS CMS for website content management and template development, it is crucial to flexibly use built-in filters to enhance efficiency. Among them,splitThe filter is well-regarded for its practicality in handling string splitting. Many users, when dealing with strings such as"1_2_3_4"which contain numbers, may wonder how tosplitThe array elements obtained after filtering are they of numeric type or string type.

To fully understand this issue, we must first clarify the working mechanism of the security CMS template engine.Anqi CMS uses syntax similar to Django template engine, and this template language usually adheres to a design philosophy of 'not guessing data types as much as possible'.This means that unless you explicitly indicate a type conversion, the data will maintain its original type passed from the backend in the template.

splitThe working principle of the filter

splitThe main function of the filter is to split a string into an array of substrings based on the delimiter you specify (in Go language, it is called)slice). For example, when you have a string"1_2_3_4"and use"_"As a delimiter,splitit will decompose it into["1", "2", "3", "4"].

The key is that even if the subparts of the original string look like numbers,"1"/"2",AftersplitThe elements cut out after the filter processing still maintain their string type.The template engine does not automatically attempt to convert them to numbers because it cannot determine whether these 'numeric strings' are to be used in mathematical operations or simply displayed as text (e.g., version numbers, encoding, etc.).

We can verify this with a simple template code. Suppose we have a variablemy_stringThe value is"1_2_3_4":

{% set my_string = "1_2_3_4" %}
{% set parts = my_string|split:"_" %}

<p>原始字符串：{{ my_string }}</p>
<p>分割后的数组（内部表示）：{{ parts|stringformat:"%#v" }}</p>
<p>数组的第一个元素：{{ parts.0 }}</p>
<p>数组的第一个元素的类型：字符串</p>

In the above code,{{ parts|stringformat:"%#v" }}This line will print out theslicedetailed structure of this in Go language, you will see it displayed as[]string{"1", "2", "3", "4"}This clearly indicates that the array element is of string type. Even if you try to perform mathematical operations onparts.0Perform direct mathematical operations, such as{{ parts.0 + 1 }}The template engine may report errors or produce unexpected results because it tries to concatenate strings and numbers instead of summing them up.

When you need a numeric type: explicit conversion

SincesplitThe string array is obtained after cutting, and when you indeed need to perform numerical calculations or comparisons on these elements, you need to use the type conversion filter provided by the Anqi CMS template. Anqi CMS providesintegerandfloatThese two filters are used to explicitly convert strings to integers or floating-point numbers.

For example, if you want to convert the first element after splitting"1"Convert to a number and perform addition operations:

{% set my_string = "1_2_3_4" %}
{% set parts = my_string|split:"_" %}

<p>原始字符串元素：{{ parts.0 }}</p>
<p>转换为整数：{{ parts.0|integer }}</p>
<p>转换为整数后进行加法运算（1 + 5）：{{ parts.0|integer|add:5 }}</p>

This code will first convertparts.0(which is a string)"1") to the same port of the AnQiCMS application instance (the default is usuallyintegerthe filter to an integer1After that, useaddFilter is related to5Add, and the final result is6. Similarly, if your numbers may contain decimals, you can usefloatby the filter.

Practical suggestions and precautions

In the template development of AnQi CMS, handling data types is an important aspect to pay attention to. Always keep the following points in mind to help you avoid potential problems:

  1. Specify data source type:Data obtained from the backend, it usually maintains its original type in the template.
  2. The "what you see is what you get" principle: splitThe any part cut out from the string by the filter, even if it looks like a number, is still a string.
  3. Explicit conversion is the way to go:Only use it when you explicitly need to perform numerical operations, comparisons, or specific formatting on strings.integerorfloatExplicit type conversion with filters.
  4. Consider the possibility of conversion failure:If you are unsure whether a string can be successfully converted to a number (for example"1_A_3"of"A"Please check before conversion, or handle conversion failure in the template logic to avoid display errors on the page.

By using this explicit data type handling method, you can more accurately control the rendering logic of the template, ensuring the stability and performance of the website, thereby providing users with a smoother browsing experience.

Common Questions (FAQ)

  1. Q: Why does the Qiyuan CMS not convert numeric string to numeric type directly?splitThe filter does not directly convert numeric string to numeric type?A: This is mainly due to the design philosophy of the template engine and performance considerations.The template engine usually tries to keep the data in its original type passed from the backend, avoiding speculative type conversions.splitEnglish translation: Automatic conversion may cause unnecessary computational overhead, or in some cases, users may wish"1_2_3_4"As text processing (such as version numbers or product codes), rather than performing mathematical operations, automatic conversion may cause inconvenience.Explicit conversion allows developers to control data processing methods more accurately.

  2. Q: How can I judge?splitEnglish: 后的元素是否可以成功转换为数字，以避免转换错误？English: A: 安企CMS的模板引擎本身没有直接的is_numericorcan_convert_to_numberThis type of filter.But you can deal with it in some indirect ways.For example, you can handle strings that may not be converted on the backend by setting a default value or a specific identifier, or by attempting to convert them in the template and then checking the conversion result."A"|integerYou will get0If you know that the original data will not have real0This can be used as a judgment basis. For more complex validations, it is usually recommended to complete the backend logic in Go language, and then pass clean data to the template after processing.

  3. Q:make_listfilters andsplitWhat are the differences in the use of the filter?A:splitThe filter splits the string based on one or more characters specified as 'delimiters', for example"a,b,c"|split:","You will get["a", "b", "c"].make_listThe filter splits each independent UTF-8 character in a string into an element of an array, without the concept of a delimiter. For example,"你好世界"|make_listYou will get["你", "好", "世", "界"]. When you need to split by a specific pattern (such as comma, underscore) usesplit, when you need to process the string word by word usemake_list.