Regex pattern that ensures that atleast one character is present along with other conditions

I am trying to validate a string based on the three conditions below

1. It must contain a string
2. It should not contain any special characters except . and -.
3. Numbers are allowed but not necessary

I formed this regex ^(?=.*[a-zA-Z])[a-zA-Z0-9\.\- ]*$ with the help of hit and trial. And it works in all the online tools available for testing. But I am not able to use this in the code

package main

import (
	"fmt"
	"regexp"
)

func main() {
	rule := regexp.MustCompile(`^(?=.*[a-zA-Z])[a-zA-Z0-9\.\- ]*$`).MatchString
	fmt.Println(rule("test_string"))
}

The error says

panic: regexp: Compile(`^(?=.*[a-zA-Z])[a-zA-Z0-9\.\- ]*$`): error parsing regexp: invalid or unsupported Perl syntax: `(?=`

Even though it works in other online tools. How can I fix this?

go does not support lookaround assertions, but you can omit the lookarounds by matching the allowed characters.

You can match a single char A-Za-z between optionally matching any of the allowed characters.

^[0-9. -]*[a-zA-Z][a-zA-Z0-9. -]*$

Explanation

• ^ Start of string
• [0-9. -]* Optionally match any of the allowed chars without a-zA-Z
• [a-zA-Z] Match a single char a-zA-Z
• [a-zA-Z0-9. -]* Optionally match any of all the allowed chars
• $ End of string

Regex demo

package main

import (
    "fmt"
    "regexp"
)

func main() {
    rule := regexp.MustCompile(`^[0-9. -]*[a-zA-Z][a-zA-Z0-9. -]*$`).MatchString
    fmt.Println(rule("test_string"))
    fmt.Println(rule("this is a test"))
}

Output

false
true