open-nomad/command/data_format.go

101 lines
2.1 KiB
Go

package command
import (
"bytes"
"fmt"
"io"
"text/template"
"github.com/hashicorp/go-msgpack/codec"
)
var (
jsonHandlePretty = &codec.JsonHandle{
HTMLCharsAsIs: true,
Indent: 4,
}
)
//DataFormatter is a transformer of the data.
type DataFormatter interface {
// TransformData should return transformed string data.
TransformData(interface{}) (string, error)
}
// DataFormat returns the data formatter specified format.
func DataFormat(format, tmpl string) (DataFormatter, error) {
switch format {
case "json":
if len(tmpl) > 0 {
return nil, fmt.Errorf("json format does not support template option.")
}
return &JSONFormat{}, nil
case "template":
return &TemplateFormat{tmpl}, nil
}
return nil, fmt.Errorf("Unsupported format is specified.")
}
type JSONFormat struct {
}
// TransformData returns JSON format string data.
func (p *JSONFormat) TransformData(data interface{}) (string, error) {
var buf bytes.Buffer
enc := codec.NewEncoder(&buf, jsonHandlePretty)
err := enc.Encode(data)
if err != nil {
return "", err
}
return buf.String(), nil
}
type TemplateFormat struct {
tmpl string
}
// TransformData returns template format string data.
func (p *TemplateFormat) TransformData(data interface{}) (string, error) {
var out io.Writer = new(bytes.Buffer)
if len(p.tmpl) == 0 {
return "", fmt.Errorf("template needs to be specified the golang templates.")
}
t, err := template.New("format").Parse(p.tmpl)
if err != nil {
return "", err
}
err = t.Execute(out, data)
if err != nil {
return "", err
}
return fmt.Sprint(out), nil
}
func Format(json bool, template string, data interface{}) (string, error) {
var format string
if json && len(template) > 0 {
return "", fmt.Errorf("Both json and template formatting are not allowed")
} else if json {
format = "json"
} else if len(template) > 0 {
format = "template"
} else {
return "", fmt.Errorf("no formatting option given")
}
f, err := DataFormat(format, template)
if err != nil {
return "", err
}
out, err := f.TransformData(data)
if err != nil {
return "", fmt.Errorf("Error formatting the data: %s", err)
}
return out, nil
}