Add fromJson and mustFromJson funcs

defaults.go

@@ -63,6 +63,19 @@ func coalesce(v ...interface{}) interface{} {
 	return nil
 }
 
+// fromJson decodes JSON into a structured value, ignoring errors.
+func fromJson(v string) interface{} {
+	output, _ := mustFromJson(v)
+	return output
+}
+
+// mustFromJson decodes JSON into a structured value, returning errors.
+func mustFromJson(v string) (interface{}, error) {
+	var output interface{}
+	err := json.Unmarshal([]byte(v), &output)
+	return output, err
+}
+
 // toJson encodes an item into a JSON string
 func toJson(v interface{}) string {
 	output, _ := json.Marshal(v)

defaults_test.go

@@ -83,6 +83,22 @@ func TestCoalesce(t *testing.T) {
 	}
 }
 
+func TestFromJson(t *testing.T) {
+	dict := map[string]interface{}{"Input": `{"foo": 55}`}
+
+	tpl := `{{.Input | fromJson}}`
+	expected := `map[foo:55]`
+	if err := runtv(tpl, expected, dict); err != nil {
+		t.Error(err)
+	}
+
+	tpl = `{{(.Input | fromJson).foo}}`
+	expected = `55`
+	if err := runtv(tpl, expected, dict); err != nil {
+		t.Error(err)
+	}
+}
+
 func TestToJson(t *testing.T) {
 	dict := map[string]interface{}{"Top": map[string]interface{}{"bool": true, "string": "test", "number": 42}}
 

docs/defaults.md

@@ -58,6 +58,15 @@ The above will first check to see if `.name` is empty. If it is not, it will ret
 that value. If it _is_ empty, `coalesce` will evaluate `.parent.name` for emptiness.
 Finally, if both `.name` and `.parent.name` are empty, it will return `Matt`.
 
+## fromJson, mustFromJson
+
+`fromJson` decodes a JSON document into a structure. If the input cannot be decoded as JSON the function will return an empty string.
+`mustFromJson` will return an error in case the JSON is invalid.
+
+```
+fromJson "{\"foo\": 55}"
+```
+
 ## toJson, mustToJson
 
 The `toJson` function encodes an item into a JSON string. If the item cannot be converted to JSON the function will return an empty string.

docs/index.md

@@ -7,7 +7,7 @@ The Sprig library provides over 70 template functions for Go's template language
 - [Math Functions](math.md): `add`, `max`, `mul`, etc.
   - [Integer Slice Functions](integer_slice.md): `until`, `untilStep`
 - [Date Functions](date.md): `now`, `date`, etc.
-- [Defaults Functions](defaults.md): `default`, `empty`, `coalesce`, `toJson`, `toPrettyJson`, `toRawJson`, `ternary`
+- [Defaults Functions](defaults.md): `default`, `empty`, `coalesce`, `fromJson`, `toJson`, `toPrettyJson`, `toRawJson`, `ternary`
 - [Encoding Functions](encoding.md): `b64enc`, `b64dec`, etc.
 - [Lists and List Functions](lists.md): `list`, `first`, `uniq`, etc.
 - [Dictionaries and Dict Functions](dicts.md): `get`, `set`, `dict`, `hasKey`, `pluck`, `deepCopy`, etc.

functions.go

@@ -216,9 +216,11 @@ var genericMap = map[string]interface{}{
 	"coalesce":         coalesce,
 	"compact":          compact,
 	"mustCompact":      mustCompact,
+	"fromJson":         fromJson,
 	"toJson":           toJson,
 	"toPrettyJson":     toPrettyJson,
 	"toRawJson":        toRawJson,
+	"mustFromJson":     mustFromJson,
 	"mustToJson":       mustToJson,
 	"mustToPrettyJson": mustToPrettyJson,
 	"mustToRawJson":    mustToRawJson,