This is a lean but comprehensive implementation of the Alfred Script Filter JSON Format to get Alfred workflows off the ground quickly with blazingly fast script filters in Go that can be seamlessly developed inside or outside Alfred.

It uses standard, familiar Go syntax and conventions as much as possible for rapid use by Go developers and integration with other Go code.

go get github.com/drgrib/alfred

full-json.md has examples of how to produce the full range of JSON output for Alfred's Script Filter JSON Format.

Let's say we want to create a simple script filter that converts a given query to title case, lower case, or upper case, for which Go conveniently has built-in support.

Let's start by prototyping our logic in Go with a case.go file in our workflow folder. We can do this on the command line or in the editor of our choice and easily run it inside or outside of Alfred:

package main

import (
	"strings"

	"github.com/drgrib/alfred"
)

func addCases(arg string) {
	titlecase := strings.Title(arg)
	alfred.Add(alfred.Item{
		Title:    titlecase,
		Subtitle: "Title",
		Arg:      titlecase,
		UID:      "titlecase",
	})

	lowercase := strings.ToLower(arg)
	alfred.Add(alfred.Item{
		Title:    lowercase,
		Subtitle: "Lower",
		Arg:      lowercase,
		UID:      "lowercase",
	})

	uppercase := strings.ToUpper(arg)
	alfred.Add(alfred.Item{
		Title:    uppercase,
		Subtitle: "Upper",
		Arg:      uppercase,
		UID:      "uppercase",
	})
}

func main() {
	arg := "just a test"
	addCases(arg)
	alfred.Run()
}

{
    "items": [
        {
            "uid": "title",
            "title": "Just A Test",
            "subtitle": "Title",
            "arg": "Just A Test"
        },
        {
            "uid": "lower",
            "title": "just a test",
            "subtitle": "Lower",
            "arg": "just a test"
        },
        {
            "uid": "upper",
            "title": "JUST A TEST",
            "subtitle": "Upper",
            "arg": "JUST A TEST"
        }
    ]
}

Looks good. Now let's add os.Args support and test it on the command line to simulate Alfred input:

package main

import (
	"os"
	"strings"

	"github.com/drgrib/alfred"
)

// [same stuff in the middle]

func main() {
	arg := os.Args[1]
	addCases(arg)
	alfred.Run()
}

go build case.go
./case "another test"

{
    "items": [
        {
            "uid": "title",
            "title": "Another Test",
            "subtitle": "Title",
            "arg": "Another Test"
        },
        {
            "uid": "lower",
            "title": "another test",
            "subtitle": "Lower",
            "arg": "another test"
        },
        {
            "uid": "upper",
            "title": "ANOTHER TEST",
            "subtitle": "Upper",
            "arg": "ANOTHER TEST"
        }
    ]
}

Right again. Alright. Now let's drop this into our script filter:

And give it a whirl:

Why not copy these to the clipboard so we can actually use them?

With a few simple runs and a glance at the Alfred clipboard history, we can see we are ready for business:

Easy!