Merge pull request #4 from claudioluciano/feature/support_json_tags

feat: add support for parsing struct json tags

README.md

@@ -19,7 +19,7 @@ v := struct {
     Name: "John",
 }
 
-parsed := Parse(v)
+parsed, err := Parse(v)
 ```
 
 The `parsed` variable will now contain a map with the same fields as the input struct:
@@ -35,7 +35,7 @@ map[string]interface{}{
 
 The output format of the `Parse` function depends on the input type:
 
-- Struct: the output is a map with the same fields as the input struct. The keys of the map are the field names, and the values are the field types represented as strings.
+- Struct: the output is a map with the same fields as the input struct. The keys of the map are the field names (if `json` tags is being used, the name attribute will be the key), and the values are the field types represented as strings.
 
 - Map: the output is a map with the same keys as the input map. The values of the map are the corresponding types of the input map values, represented as strings.
 
@@ -50,16 +50,16 @@ Here are some examples of input and output for the `Parse` function:
 ```go
 // Struct
 v := struct {
-    Age  int
+    Age  int `json:"age"`
     Name string
 }{
     Age:  30,
     Name: "John",
 }
 
-parsed := Parse(v)
+parsed, err := Parse(v)
 // parsed = map[string]interface{}{
-//     "Age":  "int",
+//     "age":  "int",
 //     "Name": "string",
 // }
 
@@ -69,7 +69,7 @@ v := map[string]int{
     "bar": 69,
 }
 
-parsed := Parse(v)
+parsed, err := Parse(v)
 // parsed = map[string]interface{}{
 //     "foo": "int",
 //     "bar": "int",
@@ -81,7 +81,7 @@ v := []interface{}{
     42,
 }
 
-parsed := Parse(v)
+parsed, err := Parse(v)
 // parsed = []interface{}{
 //     "string",
 //     "int",
@@ -91,6 +91,6 @@ parsed := Parse(v)
 // Primitive types
 v := true
 
-parsed := Parse(v)
+parsed, err := Parse(v)
 // parsed = "bool"
 ```

go.mod

@@ -1,3 +1,5 @@
 module github.com/claudioluciano/simple_json_schema_like
 
 go 1.18
+
+require github.com/fatih/structtag v1.2.0

go.sum

@@ -0,0 +1,2 @@
+github.com/fatih/structtag v1.2.0 h1:/OdNE99OxoI/PqaW/SuSK9uxxT3f/tcSZgon/ssNSx4=
+github.com/fatih/structtag v1.2.0/go.mod h1:mBJUNpUnHmRKrKlQQlmCrh5PuhftFbNv8Ys4/aAZl94=

parser.go

@@ -3,6 +3,8 @@ package simplejsonschemalike
 import (
 	"fmt"
 	"reflect"
+
+	"github.com/fatih/structtag"
 )
 
 const timeStringKind = "time.Time"
@@ -23,17 +25,16 @@ const timeStringKind = "time.Time"
 //
 // The function returns an interface{} value that can be asserted to the appropriate type
 // after the function call.
-func Parse(in interface{}) interface{} {
+func Parse(in interface{}) (interface{}, error) {
 	v := reflect.ValueOf(in)
-
 	return parse(v)
 }
 
-func parse(v reflect.Value) interface{} {
+func parse(v reflect.Value) (interface{}, error) {
 	switch v.Kind() {
 	case reflect.Struct:
 		if ok := isTime(v); ok {
-			return "date-time"
+			return "date-time", nil
 		}
 
 		return parseStruct(v)
@@ -46,7 +47,7 @@ func parse(v reflect.Value) interface{} {
 	case reflect.Slice, reflect.Array:
 		return parseSlice(v)
 	default:
-		return v.Type().String()
+		return v.Type().String(), nil
 	}
 }
 
@@ -58,7 +59,7 @@ func parseNil(v reflect.Value) interface{} {
 	return v.Type().String()
 }
 
-func parseStruct(v reflect.Value) map[string]interface{} {
+func parseStruct(v reflect.Value) (map[string]interface{}, error) {
 	m := make(map[string]interface{})
 
 	for i := 0; i < v.NumField(); i++ {
@@ -68,38 +69,72 @@ func parseStruct(v reflect.Value) map[string]interface{} {
 			continue
 		}
 
-		m[field.Name] = parse(v.Field(i))
+		name := field.Name
+		tagName, err := getNameFromTag(field)
+		if err != nil {
+			return nil, err
+		}
+		if tagName != "" {
+			name = tagName
+		}
+
+		v, err := parse(v.Field(i))
+		if err != nil {
+			return nil, err
+		}
+
+		m[name] = v
 	}
 
-	return m
+	return m, nil
 }
 
-func parseInterface(v reflect.Value) interface{} {
+func getNameFromTag(field reflect.StructField) (string, error) {
+	tags, err := structtag.Parse(string(field.Tag))
+	if err != nil {
+		return "", err
+	}
+
+	jsonTag, err := tags.Get("json")
+	if err != nil {
+		// json tag does not exist
+		return "", nil
+	}
+
+	return jsonTag.Name, nil
+}
+
+func parseInterface(v reflect.Value) (interface{}, error) {
 	field := v.Elem()
 	return parse(field)
 }
 
-func parsePrt(v reflect.Value) interface{} {
+func parsePrt(v reflect.Value) (interface{}, error) {
 	if v.IsNil() {
-		return parseNil(v)
+		return parseNil(v), nil
 	}
 
 	field := v.Elem()
 	return parse(field)
 }
 
-func parseMap(v reflect.Value) interface{} {
+func parseMap(v reflect.Value) (interface{}, error) {
 	m := make(map[string]interface{})
 
 	for _, key := range v.MapKeys() {
 		value := v.MapIndex(key)
-		m[key.String()] = parse(value)
+		v, err := parse(value)
+		if err != nil {
+			return nil, err
+		}
+
+		m[key.String()] = v
 	}
 
-	return m
+	return m, nil
 }
 
-func parseSlice(v reflect.Value) interface{} {
+func parseSlice(v reflect.Value) (interface{}, error) {
 	if v.Len() == 0 {
 		el := v.Type().Elem()
 		elType := el.String()
@@ -108,17 +143,21 @@ func parseSlice(v reflect.Value) interface{} {
 			elType = "any"
 		}
 
-		return fmt.Sprintf("[%v]", elType)
+		return fmt.Sprintf("[%v]", elType), nil
 	}
 
 	var m []interface{}
 	for i := 0; i < v.Len(); i++ {
 		field := v.Index(i)
-		t := parse(field)
+		t, err := parse(field)
+		if err != nil {
+			return nil, err
+		}
+
 		m = append(m, t)
 	}
 
-	return m
+	return m, nil
 }
 
 func isTime(v reflect.Value) bool {

parser_test.go

@@ -111,7 +111,7 @@ func TestParse(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			actual := Parse(tt.input)
+			actual, _ := Parse(tt.input)
 
 			expectedMap := make(map[string]interface{})
 			expectedBytes, _ := json.Marshal(actual)