Add ability to mark flags as required or exclusive as a group (#1654)

This change adds two features for dealing with flags:
 - requiring flags be provided as a group (or not at all)
 - requiring flags be mutually exclusive of each other

By utilizing the flag annotations we can mark which flag groups
a flag is a part of and during the parsing process we track which
ones we have seen or not.

A flag may be a part of multiple groups. The list of flags and the
type of group (required together or exclusive) make it a unique group.

Signed-off-by: John Schnake <jschnake@vmware.com>
This commit is contained in:
John Schnake 2022-04-17 16:04:57 -05:00 committed by GitHub
parent bf6cb5804d
commit 68b6b24f0c
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
5 changed files with 354 additions and 7 deletions

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@ -863,6 +863,10 @@ func (c *Command) execute(a []string) (err error) {
if err := c.validateRequiredFlags(); err != nil { if err := c.validateRequiredFlags(); err != nil {
return err return err
} }
if err := c.validateFlagGroups(); err != nil {
return err
}
if c.RunE != nil { if c.RunE != nil {
if err := c.RunE(c, argWoFlags); err != nil { if err := c.RunE(c, argWoFlags); err != nil {
return err return err

174
flag_groups.go Normal file
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@ -0,0 +1,174 @@
// Copyright © 2022 Steve Francia <spf@spf13.com>.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package cobra
import (
"fmt"
"sort"
"strings"
flag "github.com/spf13/pflag"
)
const (
requiredAsGroup = "cobra_annotation_required_if_others_set"
mutuallyExclusive = "cobra_annotation_mutually_exclusive"
)
// MarkFlagsRequiredTogether marks the given flags with annotations so that Cobra errors
// if the command is invoked with a subset (but not all) of the given flags.
func (c *Command) MarkFlagsRequiredTogether(flagNames ...string) {
c.mergePersistentFlags()
for _, v := range flagNames {
f := c.Flags().Lookup(v)
if f == nil {
panic(fmt.Sprintf("Failed to find flag %q and mark it as being required in a flag group", v))
}
if err := c.Flags().SetAnnotation(v, requiredAsGroup, append(f.Annotations[requiredAsGroup], strings.Join(flagNames, " "))); err != nil {
// Only errs if the flag isn't found.
panic(err)
}
}
}
// MarkFlagsMutuallyExclusive marks the given flags with annotations so that Cobra errors
// if the command is invoked with more than one flag from the given set of flags.
func (c *Command) MarkFlagsMutuallyExclusive(flagNames ...string) {
c.mergePersistentFlags()
for _, v := range flagNames {
f := c.Flags().Lookup(v)
if f == nil {
panic(fmt.Sprintf("Failed to find flag %q and mark it as being in a mutually exclusive flag group", v))
}
// Each time this is called is a single new entry; this allows it to be a member of multiple groups if needed.
if err := c.Flags().SetAnnotation(v, mutuallyExclusive, append(f.Annotations[mutuallyExclusive], strings.Join(flagNames, " "))); err != nil {
panic(err)
}
}
}
// validateFlagGroups validates the mutuallyExclusive/requiredAsGroup logic and returns the
// first error encountered.
func (c *Command) validateFlagGroups() error {
if c.DisableFlagParsing {
return nil
}
flags := c.Flags()
// groupStatus format is the list of flags as a unique ID,
// then a map of each flag name and whether it is set or not.
groupStatus := map[string]map[string]bool{}
mutuallyExclusiveGroupStatus := map[string]map[string]bool{}
flags.VisitAll(func(pflag *flag.Flag) {
processFlagForGroupAnnotation(flags, pflag, requiredAsGroup, groupStatus)
processFlagForGroupAnnotation(flags, pflag, mutuallyExclusive, mutuallyExclusiveGroupStatus)
})
if err := validateRequiredFlagGroups(groupStatus); err != nil {
return err
}
if err := validateExclusiveFlagGroups(mutuallyExclusiveGroupStatus); err != nil {
return err
}
return nil
}
func hasAllFlags(fs *flag.FlagSet, flagnames ...string) bool {
for _, fname := range flagnames {
f := fs.Lookup(fname)
if f == nil {
return false
}
}
return true
}
func processFlagForGroupAnnotation(flags *flag.FlagSet, pflag *flag.Flag, annotation string, groupStatus map[string]map[string]bool) {
groupInfo, found := pflag.Annotations[annotation]
if found {
for _, group := range groupInfo {
if groupStatus[group] == nil {
flagnames := strings.Split(group, " ")
// Only consider this flag group at all if all the flags are defined.
if !hasAllFlags(flags, flagnames...) {
continue
}
groupStatus[group] = map[string]bool{}
for _, name := range flagnames {
groupStatus[group][name] = false
}
}
groupStatus[group][pflag.Name] = pflag.Changed
}
}
}
func validateRequiredFlagGroups(data map[string]map[string]bool) error {
keys := sortedKeys(data)
for _, flagList := range keys {
flagnameAndStatus := data[flagList]
unset := []string{}
for flagname, isSet := range flagnameAndStatus {
if !isSet {
unset = append(unset, flagname)
}
}
if len(unset) == len(flagnameAndStatus) || len(unset) == 0 {
continue
}
// Sort values, so they can be tested/scripted against consistently.
sort.Strings(unset)
return fmt.Errorf("if any flags in the group [%v] are set they must all be set; missing %v", flagList, unset)
}
return nil
}
func validateExclusiveFlagGroups(data map[string]map[string]bool) error {
keys := sortedKeys(data)
for _, flagList := range keys {
flagnameAndStatus := data[flagList]
var set []string
for flagname, isSet := range flagnameAndStatus {
if isSet {
set = append(set, flagname)
}
}
if len(set) == 0 || len(set) == 1 {
continue
}
// Sort values, so they can be tested/scripted against consistently.
sort.Strings(set)
return fmt.Errorf("if any flags in the group [%v] are set none of the others can be; %v were all set", flagList, set)
}
return nil
}
func sortedKeys(m map[string]map[string]bool) []string {
keys := make([]string, len(m))
i := 0
for k := range m {
keys[i] = k
i++
}
sort.Strings(keys)
return keys
}

151
flag_groups_test.go Normal file
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@ -0,0 +1,151 @@
// Copyright © 2022 Steve Francia <spf@spf13.com>.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package cobra
import (
"strings"
"testing"
)
func TestValidateFlagGroups(t *testing.T) {
getCmd := func() *Command {
c := &Command{
Use: "testcmd",
Run: func(cmd *Command, args []string) {
}}
// Define lots of flags to utilize for testing.
for _, v := range []string{"a", "b", "c", "d"} {
c.Flags().String(v, "", "")
}
for _, v := range []string{"e", "f", "g"} {
c.PersistentFlags().String(v, "", "")
}
subC := &Command{
Use: "subcmd",
Run: func(cmd *Command, args []string) {
}}
subC.Flags().String("subonly", "", "")
c.AddCommand(subC)
return c
}
// Each test case uses a unique command from the function above.
testcases := []struct {
desc string
flagGroupsRequired []string
flagGroupsExclusive []string
subCmdFlagGroupsRequired []string
subCmdFlagGroupsExclusive []string
args []string
expectErr string
}{
{
desc: "No flags no problem",
}, {
desc: "No flags no problem even with conflicting groups",
flagGroupsRequired: []string{"a b"},
flagGroupsExclusive: []string{"a b"},
}, {
desc: "Required flag group not satisfied",
flagGroupsRequired: []string{"a b c"},
args: []string{"--a=foo"},
expectErr: "if any flags in the group [a b c] are set they must all be set; missing [b c]",
}, {
desc: "Exclusive flag group not satisfied",
flagGroupsExclusive: []string{"a b c"},
args: []string{"--a=foo", "--b=foo"},
expectErr: "if any flags in the group [a b c] are set none of the others can be; [a b] were all set",
}, {
desc: "Multiple required flag group not satisfied returns first error",
flagGroupsRequired: []string{"a b c", "a d"},
args: []string{"--c=foo", "--d=foo"},
expectErr: `if any flags in the group [a b c] are set they must all be set; missing [a b]`,
}, {
desc: "Multiple exclusive flag group not satisfied returns first error",
flagGroupsExclusive: []string{"a b c", "a d"},
args: []string{"--a=foo", "--c=foo", "--d=foo"},
expectErr: `if any flags in the group [a b c] are set none of the others can be; [a c] were all set`,
}, {
desc: "Validation of required groups occurs on groups in sorted order",
flagGroupsRequired: []string{"a d", "a b", "a c"},
args: []string{"--a=foo"},
expectErr: `if any flags in the group [a b] are set they must all be set; missing [b]`,
}, {
desc: "Validation of exclusive groups occurs on groups in sorted order",
flagGroupsExclusive: []string{"a d", "a b", "a c"},
args: []string{"--a=foo", "--b=foo", "--c=foo"},
expectErr: `if any flags in the group [a b] are set none of the others can be; [a b] were all set`,
}, {
desc: "Persistent flags utilize both features and can fail required groups",
flagGroupsRequired: []string{"a e", "e f"},
flagGroupsExclusive: []string{"f g"},
args: []string{"--a=foo", "--f=foo", "--g=foo"},
expectErr: `if any flags in the group [a e] are set they must all be set; missing [e]`,
}, {
desc: "Persistent flags utilize both features and can fail mutually exclusive groups",
flagGroupsRequired: []string{"a e", "e f"},
flagGroupsExclusive: []string{"f g"},
args: []string{"--a=foo", "--e=foo", "--f=foo", "--g=foo"},
expectErr: `if any flags in the group [f g] are set none of the others can be; [f g] were all set`,
}, {
desc: "Persistent flags utilize both features and can pass",
flagGroupsRequired: []string{"a e", "e f"},
flagGroupsExclusive: []string{"f g"},
args: []string{"--a=foo", "--e=foo", "--f=foo"},
}, {
desc: "Subcmds can use required groups using inherited flags",
subCmdFlagGroupsRequired: []string{"e subonly"},
args: []string{"subcmd", "--e=foo", "--subonly=foo"},
}, {
desc: "Subcmds can use exclusive groups using inherited flags",
subCmdFlagGroupsExclusive: []string{"e subonly"},
args: []string{"subcmd", "--e=foo", "--subonly=foo"},
expectErr: "if any flags in the group [e subonly] are set none of the others can be; [e subonly] were all set",
}, {
desc: "Subcmds can use exclusive groups using inherited flags and pass",
subCmdFlagGroupsExclusive: []string{"e subonly"},
args: []string{"subcmd", "--e=foo"},
}, {
desc: "Flag groups not applied if not found on invoked command",
subCmdFlagGroupsRequired: []string{"e subonly"},
args: []string{"--e=foo"},
},
}
for _, tc := range testcases {
t.Run(tc.desc, func(t *testing.T) {
c := getCmd()
sub := c.Commands()[0]
for _, flagGroup := range tc.flagGroupsRequired {
c.MarkFlagsRequiredTogether(strings.Split(flagGroup, " ")...)
}
for _, flagGroup := range tc.flagGroupsExclusive {
c.MarkFlagsMutuallyExclusive(strings.Split(flagGroup, " ")...)
}
for _, flagGroup := range tc.subCmdFlagGroupsRequired {
sub.MarkFlagsRequiredTogether(strings.Split(flagGroup, " ")...)
}
for _, flagGroup := range tc.subCmdFlagGroupsExclusive {
sub.MarkFlagsMutuallyExclusive(strings.Split(flagGroup, " ")...)
}
c.SetArgs(tc.args)
err := c.Execute()
switch {
case err == nil && len(tc.expectErr) > 0:
t.Errorf("Expected error %q but got nil", tc.expectErr)
case err != nil && err.Error() != tc.expectErr:
t.Errorf("Expected error %q but got %q", tc.expectErr, err)
}
})
}
}

8
go.sum
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@ -2,17 +2,11 @@ github.com/cpuguy83/go-md2man/v2 v2.0.1 h1:r/myEWzV9lfsM1tFLgDyu0atFtJ1fXn261LKY
github.com/cpuguy83/go-md2man/v2 v2.0.1/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o= github.com/cpuguy83/go-md2man/v2 v2.0.1/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM= github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8= github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
github.com/kr/pretty v0.2.0 h1:s5hAObm+yFO5uHYt5dYjxi2rXrsnmRpJx4OYvIWUaQs=
github.com/kr/pretty v0.2.0/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk= github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=
github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM= github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA= github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg= github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0= gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY= gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ= gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=

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@ -300,6 +300,30 @@ rootCmd.PersistentFlags().StringVarP(&Region, "region", "r", "", "AWS region (re
rootCmd.MarkPersistentFlagRequired("region") rootCmd.MarkPersistentFlagRequired("region")
``` ```
### Flag Groups
If you have different flags that must be provided together (e.g. if they provide the `--username` flag they MUST provide the `--password` flag as well) then
Cobra can enforce that requirement:
```go
rootCmd.Flags().StringVarP(&u, "username", "u", "", "Username (required if password is set)")
rootCmd.Flags().StringVarP(&pw, "password", "p", "", "Password (required if username is set)")
rootCmd.MarkFlagsRequiredTogether("username", "password")
```
You can also prevent different flags from being provided together if they represent mutually
exclusive options such as specifying an output format as either `--json` or `--yaml` but never both:
```go
rootCmd.Flags().BoolVar(&u, "json", false, "Output in JSON")
rootCmd.Flags().BoolVar(&pw, "yaml", false, "Output in YAML")
rootCmd.MarkFlagsMutuallyExclusive("json", "yaml")
```
In both of these cases:
- both local and persistent flags can be used
- **NOTE:** the group is only enforced on commands where every flag is defined
- a flag may appear in multiple groups
- a group may contain any number of flags
## Positional and Custom Arguments ## Positional and Custom Arguments
Validation of positional arguments can be specified using the `Args` field Validation of positional arguments can be specified using the `Args` field