When developing templates in AnQiCMS, we often need to handle strings, splitting them into different parts for dynamic display.splitA filter is a very practical tool that can help us split strings into arrays according to a specified delimiter. But have you ever wondered, what happens when a string does not contain the specified delimiter?splitWhat kind of array result will the filter return? This is the core issue we are going to delve into today.

splitOverview of the working principle of the filter

In the template syntax of AnQiCMS,splitThe filter follows a design similar to the Django template engine, it accepts a string as input, and splits it according to the delimiter provided.

Generally speaking,splitThe filter's role is self-evident. For example, when we have a string containing a comma-separated"apple,banana,orange"and using a comma","as a delimiter, it will naturally return["apple", "banana", "orange"]Such an array containing multiple elements. This is very convenient for handling list data or structured text.

When the delimiter is not found: unexpected 'single-element array'.

However,splitThe filter's behavior when processing a string that does not find the specified delimiter is particularly crucial, and it is often a detail that users tend to overlook. According to the design of the AnQiCMS template filter, ifsplitThe filter does not find any specified delimiter in the target string, it will not return an empty array but will return anOne element onlyThe array. This unique element is the original, uncut entire string itself.

Let's understand this with an example: Assuming we have a string"Hello AnQiCMS"we try to use hyphens"-"to split it. Since this string does not contain hyphens, you might expect to get an empty array. However,splitthe filter will return["Hello AnQiCMS"].

This pattern of behavior has a direct impact on the logical judgments and data processing in the template. For example, if you are processing the result array and expect to determine whether the string has been successfully cut by judging the length of the array, then it is only necessary to judge数组长度 > 0

Special case: when the delimiter is an empty string

In addition to the case where the delimiter is not found, there is also a special scenario that deserves our attention: when we use aempty string("") assplitThe separator in the filter. In this case,splitThe filter splits the original string into an array of individual characters, unit by unit in UTF-8.

For example, the string"你好"If an empty string is used""as a separator, it will return["你", "好"].

Practical examples: under multiple scenariossplitFilter behavior

In order to better illustrate these situations, let us demonstrate through some specific template codesplitDifferent behaviors of the filter:

{# 示例1：分隔符存在并成功切割 #}
{% set str1 = "apple,banana,orange" %}
{% set arr1 = str1|split:"," %}
<p>原始字符串："{{ str1 }}"</p>
<p>使用 "," 分隔后（期望结果）：{{ arr1|join(" | ") }}</p>
<p>数组长度：{{ arr1|length }}</p>
<hr>

{# 示例2：分隔符不存在 #}
{% set str2 = "Hello AnQiCMS World" %}
{% set arr2 = str2|split:"-" %}
<p>原始字符串："{{ str2 }}"</p>
<p>使用 "-" 分隔后（未找到分隔符）：{{ arr2|join(" | ") }}</p>
<p>数组长度：{{ arr2|length }}</p>
<hr>

{# 示例3：分隔符为空字符串 #}
{% set str3 = "安企CMS" %}
{% set arr3 = str3|split:"" %}
<p>原始字符串："{{ str3 }}"</p>
<p>使用 "" 分隔后（按字符切割）：{{ arr3|join(" | ") }}</p>
<p>数组长度：{{ arr3|length }}</p>
<hr>

{# 示例4：空字符串进行split #}
{% set str4 = "" %}
{% set arr4 = str4|split:"," %}
<p>原始字符串："{{ str4 }}"</p>
<p>空字符串使用 "," 分隔后：{{ arr4|join(" | ") }}</p>
<p>数组长度：{{ arr4|length }}</p>

The output result of the above code:

原始字符串："apple,banana,orange"
使用 "," 分隔后（期望结果）：apple | banana | orange
数组长度：3
---

原始字符串："Hello AnQiCMS World"
使用 "-" 分隔后（未找到分隔符）：Hello AnQiCMS World
数组长度：1
---

原始字符串："安企CMS"
使用 "" 分隔后（按字符切割）：安 | 企 | C | M | S
数组长度：5
---

原始字符串：""
空字符串使用 "," 分隔后：
数组长度：0

From the example, we can clearly see that when the delimiter is not present (example 2),splitThe filter returned an array containing a single original string, not an empty array.When the delimiter is empty (example 3), it indeed splits by character.When the original string is empty (example 4), it returns an empty array.

Summary and **practice**

In summary, AnQiCMS'ssplitThe filter returns an array containing the original string itself when it is processing a string that does not find the specified delimiter.Understanding this behavior pattern can help us write more robust, more predictable template code, avoid potential logical pitfalls, and ensure the accuracy of content display.

In order to better handlesplitThis feature of the filter, it is recommended that you do in your AnQiCMS template:

  1. CombinelengthFilter and content judgment:When you need to distinguish whether a string has truly been split according to the delimiter, in addition to checking whether the length of the array is greater than 0, you can also further judge whether the first element of the array matches the original stringAbsolutely consistentTo determine whether actual cutting has occurred.
  2. UsecontainFilter pre-judgment:If you just want to know if a string contains a delimiter, or need to make a preliminary judgment before splitting, AnQiCMS providescontainThe filter would be a more direct and efficient choice. For example:{% if "Hello World"|contain:"-" %}.
  3. Handle empty string input:If your source string may be empty, please notesplitIt will return an empty array of length 0, which conforms to the expectations of most scenarios.

Frequently Asked Questions (FAQ)

1.splitWhat is the type of the elements in the array returned by the filter?Answer:splitThe filter splits the string, and each element in the array is of string type.Even if the original string contains numbers, they will be stored as strings in the array after splitting.integerorfloatThe filter converts these strings to their corresponding numeric types.

2. If I want to check if a string contains a separator without splitting it into an array, what is a recommended method?Answer: Yes, AnQiCMS template providescontainA filter specifically used to check if a string, array, key-value pair, or structure contains a certain keyword or key name. It returns directly.trueorfalseA boolean value, used beforesplitJudging the array content again is more efficient and concise.

3. How tosplitAfter cutting, safely access a certain element in the array, such as the first element?Answer: BecausesplitWhen no separator is found, an array containing the original string as a single element is returned, therefore{{ arr[0] }}Always accessible. For safer and conditional access, especially when you are unsure if the array contains multiple elements, you can combinelengtha filter to make the decision. For example:{% if arr|length > 1 %}{{ arr[1] }}{% endif %}Come to visit the second element, or{% if arr[0] != original_string %}To judge whether an actual cut has occurred.