Template function fixes and renaming (docker-archive#384)

Signed-off-by: David Chung <[email protected]>

pkg/template/funcs.go

@@ -33,7 +33,7 @@ func SplitLines(o interface{}) ([]string, error) {
 
 // FromJSON decode the input JSON encoded as string or byte slice into a map.
 func FromJSON(o interface{}) (interface{}, error) {
-	ret := map[string]interface{}{}
+	var ret interface{}
 	switch o := o.(type) {
 	case string:
 		err := json.Unmarshal([]byte(o), &ret)
@@ -136,11 +136,37 @@ func (t *Template) DefaultFuncs() map[string]interface{} {
 			return make([]struct{}, c)
 		},
 
-		"var": func(name, doc string, v ...interface{}) interface{} {
+		"def": func(name string, args ...interface{}) (string, error) {
+			if _, has := t.defaults[name]; has {
+				// not sure if this is good, but should complain loudly
+				return "", fmt.Errorf("already defined: %v", name)
+			}
+			var doc string
+			var value interface{}
+			switch len(args) {
+			case 1:
+				// just value, no docs
+				value = args[0]
+			case 2:
+				// docs and value
+				doc = fmt.Sprintf("%v", args[0])
+				value = args[1]
+			}
+			t.defaults[name] = defaultValue{
+				Name:  name,
+				Value: value,
+				Doc:   doc,
+			}
+			return "", nil
+		},
+
+		"ref": func(name string) interface{} {
 			if found, has := t.binds[name]; has {
 				return found
+			} else if v, has := t.defaults[name]; has {
+				return v.Value
 			}
-			return v // default
+			return nil
 		},
 
 		"global": func(name string, v interface{}) interface{} {

pkg/template/funcs_test.go

@@ -57,6 +57,14 @@ func TestQueryObjectEncodeDecode(t *testing.T) {
 	require.NoError(t, err)
 
 	require.Equal(t, decoded, decoded2)
+
+	decoded, err = FromJSON("[]")
+	require.NoError(t, err)
+	require.Equal(t, []interface{}{}, decoded)
+
+	decoded, err = FromJSON(`{"foo":"bar"}`)
+	require.NoError(t, err)
+	require.Equal(t, map[string]interface{}{"foo": "bar"}, decoded)
 }
 
 func TestQueryObject(t *testing.T) {

pkg/template/template.go

@@ -45,16 +45,23 @@ type Options struct {
 	SocketDir string
 }
 
+type defaultValue struct {
+	Name  string
+	Value interface{}
+	Doc   string
+}
+
 // Template is the templating engine
 type Template struct {
 	options Options
 
-	url    string
-	body   []byte
-	parsed *template.Template
-	funcs  map[string]interface{}
-	binds  map[string]interface{}
-	lock   sync.Mutex
+	url      string
+	body     []byte
+	parsed   *template.Template
+	funcs    map[string]interface{}
+	binds    map[string]interface{}
+	defaults map[string]defaultValue
+	lock     sync.Mutex
 }
 
 // NewTemplate fetches the content at the url and returns a template.  If the string begins
@@ -84,11 +91,12 @@ func NewTemplateFromBytes(buff []byte, contextURL string, opt Options) (*Templat
 	}
 
 	return &Template{
-		options: opt,
-		url:     contextURL,
-		body:    buff,
-		funcs:   map[string]interface{}{},
-		binds:   map[string]interface{}{},
+		options:  opt,
+		url:      contextURL,
+		body:     buff,
+		funcs:    map[string]interface{}{},
+		binds:    map[string]interface{}{},
+		defaults: map[string]defaultValue{},
 	}, nil
 }
 

pkg/template/template_test.go

@@ -34,10 +34,15 @@ func TestVarAndGlobal(t *testing.T) {
 	str := `{{ q "locations[?state == 'WA'].name | sort(@) | {WashingtonCities: join(', ', @)}" . | global "washington-cities"}}
 
 {{/* The query above is exported and referenced somewhere else */}}
+{{ from_json "[\"SF\",\"LA\"]" | def "california-cities" "Default value for California cities" }}
+{{ from_json "{\"SF\":\"94109\",\"LA\":\"90210\"}" | def "zip-codes" "Default value for zip codes" }}
+
 {
   "test" : "hello",
   "val"  : true,
-  "result" : {{var "washington-cities" "A json with washington cities" | to_json}}
+  "result" : {{ref "washington-cities" | to_json}},
+  "california" : {{ ref "california-cities" | to_json}},
+  "sf_zip" : {{ ref "zip-codes" | q "SF" | to_json }}
 }
 `
 
@@ -59,12 +64,20 @@ func TestVarAndGlobal(t *testing.T) {
 	expected := `
 
 
+
+
+
 {
   "test" : "hello",
   "val"  : true,
   "result" : {
   "WashingtonCities": "Bellevue, Olympia, Seattle"
-}
+},
+  "california" : [
+  "SF",
+  "LA"
+],
+  "sf_zip" : "94109"
 }
 `
 	require.Equal(t, expected, view)