Slicing Strings in Go-Jira Templates: A Common Pitfall and Its Solution
Problem: You're using Go-Jira, a powerful tool for creating Jira issues from Go code. However, when you attempt to slice strings within your templates, you encounter a frustrating error: "slice is not slicing strings".
Scenario:
Imagine you're building a Jira issue report from a Go program. You want to include only the first 10 characters of a long error message in your issue summary. You might try using the following Go-Jira template:
package main
import (
"fmt"
"github.com/andygrunwald/go-jira"
)
func main() {
// ... your code ...
issue := jira.Issue{
Fields: &jira.IssueFields{
Summary: fmt.Sprintf("Error: %s", errorMessage[:10]), // Attempting to slice the string
},
}
// ... your code ...
}
Running this code will result in the dreaded "slice is not slicing strings" error.
Analysis:
The issue lies in the way Go-Jira handles templates. When you use the fmt.Sprintf function within a Go-Jira template, you're essentially injecting a string into the template. Go-Jira then parses this string and attempts to interpret it as a Go expression.
In this case, errorMessage[:10] is a valid Go expression for slicing a string. However, Go-Jira treats this expression as a literal string, leading to the error.
Solution:
To fix this, we need to ensure the slicing happens before the string is passed to the Go-Jira template. One simple way to achieve this is by using the strings.SplitN function:
package main
import (
"fmt"
"strings"
"github.com/andygrunwald/go-jira"
)
func main() {
// ... your code ...
issue := jira.Issue{
Fields: &jira.IssueFields{
Summary: fmt.Sprintf("Error: %s", strings.SplitN(errorMessage, "", 11)[0]),
},
}
// ... your code ...
}
This code uses strings.SplitN to split the errorMessage into a slice of substrings, where each substring is a single character. The second argument (11) indicates that we want a maximum of 11 substrings. We then take the first element of this slice ([0]), effectively extracting the first 10 characters.
Additional Insights:
- This approach offers a more general solution compared to simply using the
string[:10]syntax, as it allows for manipulating substrings of varying lengths. - The use of
strings.SplitNprovides a clean and efficient way to address string manipulation within Go-Jira templates.
Resources:
By understanding this common pitfall and implementing the correct solution, you can effectively manipulate strings within Go-Jira templates and build more robust and informative Jira issues.
