Overview

Below go package can be used to extract URL from a given string

https://github.com/mvdan/xurls

There are two ways of using this package

• Strict – In strict mode, it matches only URLs with a scheme

• Relaxed – In relaxed mode, it matches any URL matched by strict plus any URLs without a scheme

You can specify the scheme to filter on. There is a function for that

StrictMatchingScheme

Program

Let’s first see a program

package main

import (
	"fmt"

	"mvdan.cc/xurls/v2"
)

func main() {
	xurlsStrict := xurls.Strict()
	output := xurlsStrict.FindAllString("golangbyexample.com is https://golangbyexample.com", -1)
	fmt.Println(output)

	xurlsRelaxed := xurls.Relaxed()
	output = xurlsRelaxed.FindAllString("The website is golangbyexample.com", -1)
	fmt.Println(output)

	output = xurlsRelaxed.FindAllString("golangbyexample.com is https://golangbyexample.com", -1)
	fmt.Println(output)
}

Output

[https://golangbyexample.com]
[golangbyexample.com]
[golangbyexample.com https://golangbyexample.com]

Notice in the strict mode, it does not return the golangbyexample.com in the output as that is without a scheme.

Let’s see another program to extract multiple URLs

package main

import (
	"fmt"

	"mvdan.cc/xurls/v2"
)

func main() {
	xurlsStrict := xurls.Strict()
	input := "The webiste is https://golangbyexample.com:8000/tutorials/intro amd mail to mailto:contactus@golangbyexample.com"
	output := xurlsStrict.FindAllString(input, -1)
	fmt.Println(output)
}

Output

[https://golangbyexample.com:8000/tutorials/intro mailto:contactus@golangbyexample.com]

If we want to restrict the output to a particular scheme then that also can be done.

package main

import (
	"fmt"
	"log"

	"mvdan.cc/xurls/v2"
)

func main() {
	xurlsStrict, err := xurls.StrictMatchingScheme("https")
	if err != nil {
		log.Fatalf("Some error occured. Error: %s", err)
	}
	input := "The webiste is https://golangbyexample.com:8000/tutorials/intro amd mail to mailto:contactus@golangbyexample.com"
	output := xurlsStrict.FindAllString(input, -1)
	fmt.Println(output)
}

Output

[https://golangbyexample.com:8000/tutorials/intro]

In the above program, we provided the scheme as https which is why we have only one output