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json_flags.go
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json_flags.go
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package cmdutil
import (
"bytes"
"encoding/json"
"errors"
"fmt"
"io"
"reflect"
"sort"
"strings"
"github.com/cli/cli/v2/pkg/iostreams"
"github.com/cli/cli/v2/pkg/jsoncolor"
"github.com/cli/cli/v2/pkg/set"
"github.com/cli/go-gh/v2/pkg/jq"
"github.com/cli/go-gh/v2/pkg/template"
"github.com/spf13/cobra"
"github.com/spf13/pflag"
)
type JSONFlagError struct {
error
}
func AddJSONFlags(cmd *cobra.Command, exportTarget *Exporter, fields []string) {
f := cmd.Flags()
f.StringSlice("json", nil, "Output JSON with the specified `fields`")
f.StringP("jq", "q", "", "Filter JSON output using a jq `expression`")
f.StringP("template", "t", "", "Format JSON output using a Go template; see \"gh help formatting\"")
_ = cmd.RegisterFlagCompletionFunc("json", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
var results []string
var prefix string
if idx := strings.LastIndexByte(toComplete, ','); idx >= 0 {
prefix = toComplete[:idx+1]
toComplete = toComplete[idx+1:]
}
toComplete = strings.ToLower(toComplete)
for _, f := range fields {
if strings.HasPrefix(strings.ToLower(f), toComplete) {
results = append(results, prefix+f)
}
}
sort.Strings(results)
return results, cobra.ShellCompDirectiveNoSpace
})
oldPreRun := cmd.PreRunE
cmd.PreRunE = func(c *cobra.Command, args []string) error {
if oldPreRun != nil {
if err := oldPreRun(c, args); err != nil {
return err
}
}
if export, err := checkJSONFlags(c); err == nil {
if export == nil {
*exportTarget = nil
} else {
allowedFields := set.NewStringSet()
allowedFields.AddValues(fields)
for _, f := range export.fields {
if !allowedFields.Contains(f) {
sort.Strings(fields)
return JSONFlagError{fmt.Errorf("Unknown JSON field: %q\nAvailable fields:\n %s", f, strings.Join(fields, "\n "))}
}
}
*exportTarget = export
}
} else {
return err
}
return nil
}
cmd.SetFlagErrorFunc(func(c *cobra.Command, e error) error {
if c == cmd && e.Error() == "flag needs an argument: --json" {
sort.Strings(fields)
return JSONFlagError{fmt.Errorf("Specify one or more comma-separated fields for `--json`:\n %s", strings.Join(fields, "\n "))}
}
if cmd.HasParent() {
return cmd.Parent().FlagErrorFunc()(c, e)
}
return e
})
}
func checkJSONFlags(cmd *cobra.Command) (*jsonExporter, error) {
f := cmd.Flags()
jsonFlag := f.Lookup("json")
jqFlag := f.Lookup("jq")
tplFlag := f.Lookup("template")
webFlag := f.Lookup("web")
if jsonFlag.Changed {
if webFlag != nil && webFlag.Changed {
return nil, errors.New("cannot use `--web` with `--json`")
}
jv := jsonFlag.Value.(pflag.SliceValue)
return &jsonExporter{
fields: jv.GetSlice(),
filter: jqFlag.Value.String(),
template: tplFlag.Value.String(),
}, nil
} else if jqFlag.Changed {
return nil, errors.New("cannot use `--jq` without specifying `--json`")
} else if tplFlag.Changed {
return nil, errors.New("cannot use `--template` without specifying `--json`")
}
return nil, nil
}
func AddFormatFlags(cmd *cobra.Command, exportTarget *Exporter) {
var format string
StringEnumFlag(cmd, &format, "format", "", "", []string{"json"}, "Output format")
f := cmd.Flags()
f.StringP("jq", "q", "", "Filter JSON output using a jq `expression`")
f.StringP("template", "t", "", "Format JSON output using a Go template; see \"gh help formatting\"")
oldPreRun := cmd.PreRunE
cmd.PreRunE = func(c *cobra.Command, args []string) error {
if oldPreRun != nil {
if err := oldPreRun(c, args); err != nil {
return err
}
}
if export, err := checkFormatFlags(c); err == nil {
if export == nil {
*exportTarget = nil
} else {
*exportTarget = export
}
} else {
return err
}
return nil
}
}
func checkFormatFlags(cmd *cobra.Command) (*jsonExporter, error) {
f := cmd.Flags()
formatFlag := f.Lookup("format")
formatValue := formatFlag.Value.String()
jqFlag := f.Lookup("jq")
tplFlag := f.Lookup("template")
webFlag := f.Lookup("web")
if formatFlag.Changed {
if webFlag != nil && webFlag.Changed {
return nil, errors.New("cannot use `--web` with `--format`")
}
return &jsonExporter{
filter: jqFlag.Value.String(),
template: tplFlag.Value.String(),
}, nil
} else if jqFlag.Changed && formatValue != "json" {
return nil, errors.New("cannot use `--jq` without specifying `--format json`")
} else if tplFlag.Changed && formatValue != "json" {
return nil, errors.New("cannot use `--template` without specifying `--format json`")
}
return nil, nil
}
type Exporter interface {
Fields() []string
Write(io *iostreams.IOStreams, data interface{}) error
}
type jsonExporter struct {
fields []string
filter string
template string
}
// NewJSONExporter returns an Exporter to emit JSON.
func NewJSONExporter() *jsonExporter {
return &jsonExporter{}
}
func (e *jsonExporter) Fields() []string {
return e.fields
}
func (e *jsonExporter) SetFields(fields []string) {
e.fields = fields
}
// Write serializes data into JSON output written to w. If the object passed as data implements exportable,
// or if data is a map or slice of exportable object, ExportData() will be called on each object to obtain
// raw data for serialization.
func (e *jsonExporter) Write(ios *iostreams.IOStreams, data interface{}) error {
buf := bytes.Buffer{}
encoder := json.NewEncoder(&buf)
encoder.SetEscapeHTML(false)
if err := encoder.Encode(e.exportData(reflect.ValueOf(data))); err != nil {
return err
}
w := ios.Out
if e.filter != "" {
indent := ""
if ios.IsStdoutTTY() {
indent = " "
}
if err := jq.EvaluateFormatted(&buf, w, e.filter, indent, ios.ColorEnabled()); err != nil {
return err
}
} else if e.template != "" {
t := template.New(w, ios.TerminalWidth(), ios.ColorEnabled())
if err := t.Parse(e.template); err != nil {
return err
}
if err := t.Execute(&buf); err != nil {
return err
}
return t.Flush()
} else if ios.ColorEnabled() {
return jsoncolor.Write(w, &buf, " ")
}
_, err := io.Copy(w, &buf)
return err
}
func (e *jsonExporter) exportData(v reflect.Value) interface{} {
switch v.Kind() {
case reflect.Ptr, reflect.Interface:
if !v.IsNil() {
return e.exportData(v.Elem())
}
case reflect.Slice:
a := make([]interface{}, v.Len())
for i := 0; i < v.Len(); i++ {
a[i] = e.exportData(v.Index(i))
}
return a
case reflect.Map:
t := reflect.MapOf(v.Type().Key(), emptyInterfaceType)
m := reflect.MakeMapWithSize(t, v.Len())
iter := v.MapRange()
for iter.Next() {
ve := reflect.ValueOf(e.exportData(iter.Value()))
m.SetMapIndex(iter.Key(), ve)
}
return m.Interface()
case reflect.Struct:
if v.CanAddr() && reflect.PtrTo(v.Type()).Implements(exportableType) {
ve := v.Addr().Interface().(exportable)
return ve.ExportData(e.fields)
} else if v.Type().Implements(exportableType) {
ve := v.Interface().(exportable)
return ve.ExportData(e.fields)
}
}
return v.Interface()
}
type exportable interface {
ExportData([]string) map[string]interface{}
}
var exportableType = reflect.TypeOf((*exportable)(nil)).Elem()
var sliceOfEmptyInterface []interface{}
var emptyInterfaceType = reflect.TypeOf(sliceOfEmptyInterface).Elem()
// Basic function that can be used with structs that need to implement
// the exportable interface. It has numerous limitations so verify
// that it works as expected with the struct and fields you want to export.
// If it does not, then implementing a custom ExportData method is necessary.
// Perhaps this should be moved up into exportData for the case when
// a struct does not implement the exportable interface, but for now it will
// need to be explicitly used.
func StructExportData(s interface{}, fields []string) map[string]interface{} {
v := reflect.ValueOf(s)
if v.Kind() == reflect.Ptr {
v = v.Elem()
}
if v.Kind() != reflect.Struct {
// If s is not a struct or pointer to a struct return nil.
return nil
}
data := make(map[string]interface{}, len(fields))
for _, f := range fields {
sf := fieldByName(v, f)
if sf.IsValid() && sf.CanInterface() {
data[f] = sf.Interface()
}
}
return data
}
func fieldByName(v reflect.Value, field string) reflect.Value {
return v.FieldByNameFunc(func(s string) bool {
return strings.EqualFold(field, s)
})
}