Add support for maps defined as a json string

cast_test.go

@@ -697,6 +697,10 @@ func TestStringMapStringSliceE(t *testing.T) {
 	var stringMapInterface1 = map[string]interface{}{"key 1": []string{"value 1"}, "key 2": []string{"value 2"}}
 	var stringMapInterfaceResult1 = map[string][]string{"key 1": {"value 1"}, "key 2": {"value 2"}}
 
+	var jsonStringMapString = `{"key 1": "value 1", "key 2": "value 2"}`
+	var jsonStringMapStringArray = `{"key 1": ["value 1"], "key 2": ["value 2", "value 3"]}`
+	var jsonStringMapStringArrayResult = map[string][]string{"key 1": {"value 1"}, "key 2": {"value 2", "value 3"}}
+
 	type Key struct {
 		k string
 	}
@@ -718,11 +722,15 @@ func TestStringMapStringSliceE(t *testing.T) {
 		{interfaceMapInterfaceSlice, stringMapStringSlice, false},
 		{interfaceMapString, stringMapStringSingleSliceFieldsResult, false},
 		{interfaceMapInterface, stringMapStringSingleSliceFieldsResult, false},
+		{jsonStringMapStringArray, jsonStringMapStringArrayResult, false},
+
 		// errors
 		{nil, nil, true},
 		{testing.T{}, nil, true},
 		{map[interface{}]interface{}{"foo": testing.T{}}, nil, true},
 		{map[interface{}]interface{}{Key{"foo"}: "bar"}, nil, true}, // ToStringE(Key{"foo"}) should fail
+		{jsonStringMapString, nil, true},
+		{"", nil, true},
 	}
 
 	for i, test := range tests {
@@ -751,9 +759,13 @@ func TestToStringMapE(t *testing.T) {
 	}{
 		{map[interface{}]interface{}{"tag": "tags", "group": "groups"}, map[string]interface{}{"tag": "tags", "group": "groups"}, false},
 		{map[string]interface{}{"tag": "tags", "group": "groups"}, map[string]interface{}{"tag": "tags", "group": "groups"}, false},
+		{`{"tag": "tags", "group": "groups"}`, map[string]interface{}{"tag": "tags", "group": "groups"}, false},
+		{`{"tag": "tags", "group": true}`, map[string]interface{}{"tag": "tags", "group": true}, false},
+
 		// errors
 		{nil, nil, true},
 		{testing.T{}, nil, true},
+		{"", nil, true},
 	}
 
 	for i, test := range tests {
@@ -783,9 +795,12 @@ func TestToStringMapBoolE(t *testing.T) {
 		{map[interface{}]interface{}{"v1": true, "v2": false}, map[string]bool{"v1": true, "v2": false}, false},
 		{map[string]interface{}{"v1": true, "v2": false}, map[string]bool{"v1": true, "v2": false}, false},
 		{map[string]bool{"v1": true, "v2": false}, map[string]bool{"v1": true, "v2": false}, false},
+		{`{"v1": true, "v2": false}`, map[string]bool{"v1": true, "v2": false}, false},
+
 		// errors
 		{nil, nil, true},
 		{testing.T{}, nil, true},
+		{"", nil, true},
 	}
 
 	for i, test := range tests {
@@ -811,6 +826,9 @@ func TestToStringMapStringE(t *testing.T) {
 	var stringMapInterface = map[string]interface{}{"key 1": "value 1", "key 2": "value 2", "key 3": "value 3"}
 	var interfaceMapString = map[interface{}]string{"key 1": "value 1", "key 2": "value 2", "key 3": "value 3"}
 	var interfaceMapInterface = map[interface{}]interface{}{"key 1": "value 1", "key 2": "value 2", "key 3": "value 3"}
+	var jsonString = `{"key 1": "value 1", "key 2": "value 2", "key 3": "value 3"}`
+	var invalidJsonString = `{"key 1": "value 1", "key 2": "value 2", "key 3": "value 3"`
+	var emptyString = ""
 
 	tests := []struct {
 		input  interface{}
@@ -821,9 +839,13 @@ func TestToStringMapStringE(t *testing.T) {
 		{stringMapInterface, stringMapString, false},
 		{interfaceMapString, stringMapString, false},
 		{interfaceMapInterface, stringMapString, false},
+		{jsonString, stringMapString, false},
+
 		// errors
 		{nil, nil, true},
 		{testing.T{}, nil, true},
+		{invalidJsonString, nil, true},
+		{emptyString, nil, true},
 	}
 
 	for i, test := range tests {

caste.go

@@ -6,6 +6,7 @@
 package cast
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"html/template"
@@ -872,6 +873,9 @@ func ToStringMapStringE(i interface{}) (map[string]string, error) {
 			m[ToString(k)] = ToString(val)
 		}
 		return m, nil
+	case string:
+		err := jsonStringToObject(v, &m)
+		return m, err
 	default:
 		return m, fmt.Errorf("unable to cast %#v of type %T to map[string]string", i, i)
 	}
@@ -932,6 +936,9 @@ func ToStringMapStringSliceE(i interface{}) (map[string][]string, error) {
 			}
 			m[key] = value
 		}
+	case string:
+		err := jsonStringToObject(v, &m)
+		return m, err
 	default:
 		return m, fmt.Errorf("unable to cast %#v of type %T to map[string][]string", i, i)
 	}
@@ -955,6 +962,9 @@ func ToStringMapBoolE(i interface{}) (map[string]bool, error) {
 		return m, nil
 	case map[string]bool:
 		return v, nil
+	case string:
+		err := jsonStringToObject(v, &m)
+		return m, err
 	default:
 		return m, fmt.Errorf("unable to cast %#v of type %T to map[string]bool", i, i)
 	}
@@ -972,6 +982,9 @@ func ToStringMapE(i interface{}) (map[string]interface{}, error) {
 		return m, nil
 	case map[string]interface{}:
 		return v, nil
+	case string:
+		err := jsonStringToObject(v, &m)
+		return m, err
 	default:
 		return m, fmt.Errorf("unable to cast %#v of type %T to map[string]interface{}", i, i)
 	}
@@ -1144,3 +1157,10 @@ func parseDateWith(s string, dates []string) (d time.Time, e error) {
 	}
 	return d, fmt.Errorf("unable to parse date: %s", s)
 }
+
+// jsonStringToObject attempts to unmarshall a string as JSON into
+// the object passed as pointer.
+func jsonStringToObject(s string, v interface{}) error {
+	data := []byte(s)
+	return json.Unmarshal(data, v)
+}