How to Avoid Trailing Commas When Iterating Arrays in Go Text Templates?

Special Case Handling for the Last Element in Go Text Templates

In Go's text template system, generating a string like "(p1, p2, p3)" from an array poses unique challenges in properly placing the last comma. The following questions and answers delve into a sophisticated workaround:

Question:

How can the last (or first) element of an array be handled differently in a string template to avoid unwanted commas?

Answer:

利用 Go 的模板系统，声明两个变量来迭代数组/切片：

• $i represents the index
• $e represents the element

For instance, given an array ip = ["p1", "p2", "p3"], the following template can be used:

{{ $i := . }}
{{ $e := . }}
({{ range $i }}{{ if gt $i 0 }}, {{ end }}{{ $e }}, {{end}})

Using $index enables conditional statements like {{if $index}} to check if the current element is not the first. This ensures that a comma is only added between elements.

This solution leverages the ability of Go templates to test for zero values, unlike Go's boolean-based if statements.

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