Skip to content

Commit

Permalink
Add support for rewriting the appended module name. (#545)
Browse files Browse the repository at this point in the history 
* (M) ygot/render.go
 * (M) ygot/render_test.go
  - This change allows the contents of the `module` tag to be rewritten
    when outputting RFC7951-compatible JSON. Particularly, this is
    useful when a node that was removed from the schema is re-added
    using an augmentation, and the user wants to specify that ygot
    should pretend that the node is still in the original module.
  • Loading branch information
@robshakir
robshakir authored Jun 18, 2021
1 parent 2713b98 commit dbe2718
Show file tree
Hide file tree
Showing 2 changed files with 148 additions and 50 deletions.
69 changes: 51 additions & 18 deletions ygot/render.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -921,6 +921,19 @@ type RFC7951JSONConfig struct {
// GoStruct to determine the marshalled path elements instead of the
// "path" tag, whenever the former is present.
PreferShadowPath bool
// RewriteModuleNames specifies that, when marshalling to JSON, any
// entry that is found within module A should be assumed to be in
// module B. This allows a user to augment modules with nodes that
// are then rewritten to be part of the augmented (note augmentED)
// module's namespace. The primary reason that a user may this
// functionality is to ensure that when a node is removed from an
// model, but it is to be re-added for backwards compatibility by
// augmentation, then the original output is not modified.
//
// The RewriteModuleNames map is keyed on the name of the module that
// is to be rewritten FROM, and the value of the map is the name of the module
// it is to be rewritten TO.
RewriteModuleNames map[string]string
}

// IsMarshal7951Arg marks the RFC7951JSONConfig struct as a valid argument to
Expand All @@ -929,9 +942,8 @@ func (*RFC7951JSONConfig) IsMarshal7951Arg() {}

// ConstructIETFJSON marshals a supplied GoStruct to a map, suitable for
// handing to json.Marshal. It complies with the convention for marshalling
// to JSON described by RFC7951. The appendModName argument determines whether
// the module name should be appended to entities that are defined in a different
// module to their parent.
// to JSON described by RFC7951. The supplied args control options corresponding
// to the method by which JSON is marshalled.
func ConstructIETFJSON(s GoStruct, args *RFC7951JSONConfig) (map[string]interface{}, error) {
return structJSON(s, "", jsonOutputConfig{
jType: RFC7951,
Expand Down Expand Up @@ -1017,6 +1029,18 @@ type jsonOutputConfig struct {
rfc7951Config *RFC7951JSONConfig
}

// rewriteModName rewrites the module mod according to the specified rewrite rules.
// The rewrite rules are a map keyed by observed module name, with values of
// the name of the module that is to be rewritten to. It returns the rewritten
// module name, or the original module name in the case that it does not need
// to be rewritten.
func rewriteModName(mod string, rules map[string]string) string {
if rules == nil || rules[mod] == "" {
return mod
}
return rules[mod]
}

// structJSON marshals a GoStruct to a map[string]interface{} which can be
// handed to JSON marshal. parentMod specifies the module that the supplied
// GoStruct is defined within such that RFC7951 format JSON is able to consider
Expand All @@ -1040,23 +1064,32 @@ func structJSON(s GoStruct, parentMod string, args jsonOutputConfig) (map[string

// Determine whether we should append a module name to the path in RFC7951
// output mode.
var appmod string
var (
appmod string
appendModName bool
)

pmod := parentMod
if chMod, ok := fType.Tag.Lookup("module"); ok {
// If the child module isn't the same as the parent module,
// then appmod stores the name of the module to prefix to paths
// within this context.
if chMod != parentMod {
appmod = chMod
if args.jType == RFC7951 && args.rfc7951Config != nil && args.rfc7951Config.AppendModuleName {
if chMod, ok := fType.Tag.Lookup("module"); ok {
// If the child module isn't the same as the parent module,
// then appmod stores the name of the module to prefix to paths
// within this context.

// First we check whether we are rewriting the name of the module, so that
// we do the right comparison.
chMod = rewriteModName(chMod, args.rfc7951Config.RewriteModuleNames)

if chMod != parentMod {
appmod = chMod
}
// Update the parent module name to be used for subsequent
// children.
pmod = chMod
}
if appmod != "" {
appendModName = true
}
// Update the parent module name to be used for subsequent
// children.
pmod = chMod
}

var appendModName bool
if args.jType == RFC7951 && args.rfc7951Config != nil && args.rfc7951Config.AppendModuleName && appmod != "" {
appendModName = true
}

mapPaths, err := structTagToLibPaths(fType, newStringSliceGNMIPath([]string{}), args.rfc7951Config != nil && args.rfc7951Config.PreferShadowPath)
Expand Down
129 changes: 97 additions & 32 deletions ygot/render_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1794,14 +1794,15 @@ func (t *unmarshalableJSON) UnmarshalJSON(d []byte) error {

func TestConstructJSON(t *testing.T) {
tests := []struct {
name string
in GoStruct
inAppendMod bool
wantIETF map[string]interface{}
wantInternal map[string]interface{}
wantSame bool
wantErr bool
wantJSONErr bool
name string
in GoStruct
inAppendMod bool
inRewriteModuleNameRules map[string]string
wantIETF map[string]interface{}
wantInternal map[string]interface{}
wantSame bool
wantErr bool
wantJSONErr bool
}{{
name: "invalidGoStruct",
in: &invalidGoStructChild{
Expand Down Expand Up @@ -1873,6 +1874,67 @@ func TestConstructJSON(t *testing.T) {
},
},
},
}, {
name: "rewrite module name for an element with children",
in: &diffModAtRoot{
Child: &diffModAtRootChild{
ValueOne: String("one"),
ValueTwo: String("two"),
ValueThree: String("three"),
},
Elem: &diffModAtRootElem{
C: &diffModAtRootElemTwo{
Name: String("baz"),
},
},
},
inAppendMod: true,
inRewriteModuleNameRules: map[string]string{
// rewrite m1 to m2
"m1": "m2",
},
wantIETF: map[string]interface{}{
"m2:foo": map[string]interface{}{
"value-one": "one",
"m3:value-two": "two",
"value-three": "three",
},
"m2:baz": map[string]interface{}{
"c": map[string]interface{}{
"name": "baz",
},
},
},
}, {
name: "rewrite leaf node module",
in: &diffModAtRoot{
Child: &diffModAtRootChild{
ValueOne: String("one"),
ValueTwo: String("two"),
ValueThree: String("three"),
},
Elem: &diffModAtRootElem{
C: &diffModAtRootElemTwo{
Name: String("baz"),
},
},
},
inAppendMod: true,
inRewriteModuleNameRules: map[string]string{
"m3": "fish",
},
wantIETF: map[string]interface{}{
"m1:foo": map[string]interface{}{
"m2:value-one": "one",
"fish:value-two": "two",
"value-three": "three",
},
"m1:baz": map[string]interface{}{
"c": map[string]interface{}{
"name": "baz",
},
},
},
}, {
name: "simple render",
in: &renderExample{
Expand Down Expand Up @@ -2559,7 +2621,8 @@ func TestConstructJSON(t *testing.T) {
for _, tt := range tests {
t.Run(tt.name+" ConstructIETFJSON", func(t *testing.T) {
gotietf, err := ConstructIETFJSON(tt.in, &RFC7951JSONConfig{
AppendModuleName: tt.inAppendMod,
AppendModuleName: tt.inAppendMod,
RewriteModuleNames: tt.inRewriteModuleNameRules,
})
if (err != nil) != tt.wantErr {
t.Fatalf("ConstructIETFJSON(%v): got unexpected error: %v, want error %v", tt.in, err, tt.wantErr)
Expand All @@ -2581,31 +2644,33 @@ func TestConstructJSON(t *testing.T) {
}
})

t.Run(tt.name+" ConstructInternalJSON", func(t *testing.T) {
gotjson, err := ConstructInternalJSON(tt.in)
if (err != nil) != tt.wantErr {
t.Fatalf("ConstructJSON(%v): got unexpected error: %v", tt.in, err)
}
if err != nil {
return
}
if tt.wantSame || tt.wantInternal != nil {
t.Run(tt.name+" ConstructInternalJSON", func(t *testing.T) {
gotjson, err := ConstructInternalJSON(tt.in)
if (err != nil) != tt.wantErr {
t.Fatalf("ConstructJSON(%v): got unexpected error: %v", tt.in, err)
}
if err != nil {
return
}

_, err = json.Marshal(gotjson)
if (err != nil) != tt.wantJSONErr {
t.Fatalf("json.Marshal(%v): got unexpected error: %v, want error: %v", gotjson, err, tt.wantJSONErr)
}
if err != nil {
return
}
_, err = json.Marshal(gotjson)
if (err != nil) != tt.wantJSONErr {
t.Fatalf("json.Marshal(%v): got unexpected error: %v, want error: %v", gotjson, err, tt.wantJSONErr)
}
if err != nil {
return
}

wantInternal := tt.wantInternal
if tt.wantSame == true {
wantInternal = tt.wantIETF
}
if diff := pretty.Compare(gotjson, wantInternal); diff != "" {
t.Errorf("ConstructJSON(%v): did not get expected output, diff(-got,+want):\n%v", tt.in, diff)
}
})
wantInternal := tt.wantInternal
if tt.wantSame == true {
wantInternal = tt.wantIETF
}
if diff := pretty.Compare(gotjson, wantInternal); diff != "" {
t.Errorf("ConstructJSON(%v): did not get expected output, diff(-got,+want):\n%v", tt.in, diff)
}
})
}
}
}

Expand Down

0 comments on commit dbe2718

Please sign in to comment.