fix: Add support for multiple errors

error.go

@@ -19,14 +19,70 @@ var ErrorTypeAssert = Error{
 	Message:        "Type assertion failed",
 }
 
+type ErrorDetail struct {
+	Multiple bool
+	Errors   map[int]map[string][]string
+}
+
+func (ed *ErrorDetail) DetailsForRow(row int) (map[string][]string, error) {
+	if !ed.Multiple {
+		return nil, errors.New("error contains a single error, use Error()")
+	}
+
+	rowDetail, ok := ed.Errors[row]
+	if !ok {
+		return nil, nil
+	}
+
+	return rowDetail, nil
+}
+
+func (ed *ErrorDetail) Details() (map[string][]string, error) {
+	if ed.Multiple {
+		return nil, errors.New("error contains multiple errors, use ErrorForRow()")
+	}
+
+	return ed.Errors[0], nil
+}
+
+func (ed *ErrorDetail) UnmarshalJSON(data []byte) error {
+	// First attempt to unmarshal singular.
+	var singularErr map[string][]string
+	err := json.Unmarshal(data, &singularErr)
+	if err == nil {
+		ed.Errors = map[int]map[string][]string{
+			0: singularErr,
+		}
+		return nil
+	}
+
+	// Then attempt to unmarshal multiple.
+	var multipleErr map[int]map[string][]string
+	err = json.Unmarshal(data, &multipleErr)
+	if err == nil {
+		ed.Errors = multipleErr
+		ed.Multiple = true
+		return nil
+	}
+
+	return err
+}
+
+func (ed *ErrorDetail) MarshalJSON() ([]byte, error) {
+	if ed.Multiple {
+		return json.Marshal(ed.Errors)
+	}
+	return json.Marshal(ed.Errors[0])
+}
+
 type Error struct {
 	Err error `json:"-"`
 
 	HTTPStatusCode int    `json:"status"`
 	Message        string `json:"error"`
 	ErrorCode      string `json:"code"`
 
-	ErrorDetail map[string][]string `json:"error_details,omitempty"`
+	ErrorDetail *ErrorDetail `json:"error_details,omitempty"`
 }
 
 func (e Error) Error() string {

error_test.go

@@ -1,6 +1,7 @@
 package lago
 
 import (
+	"encoding/json"
 	"errors"
 	"testing"
 )
@@ -21,3 +22,117 @@ func TestErrorNoErr(t *testing.T) {
 	}
 	t.Logf("%s", noErr.Error())
 }
+
+func TestErrorDetails(t *testing.T) {
+	var tests = []struct {
+		name  string
+		input string
+		want  *Error
+	}{
+		{
+			name: "Single detail",
+			input: `{
+  "status": 422,
+  "error": "Unprocessable Entity",
+  "code": "validation_errors",
+  "error_details": {
+    "transaction_id": [
+      "value_already_exist"
+    ]
+  }
+}`,
+			want: &Error{
+				HTTPStatusCode: 422,
+				Message:        "Unprocessable Entity",
+				ErrorCode:      "validation_errors",
+				ErrorDetail: &ErrorDetail{
+					Multiple: false,
+					Errors: map[int]map[string][]string{
+						0: {
+							"transaction_id": {
+								"value_already_exist",
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "Multiple details",
+			input: `{
+  "status": 422,
+  "error": "Unprocessable Entity",
+  "code": "validation_errors",
+  "error_details": {
+    "0": {
+      "transaction_id": [
+        "value_already_exist"
+      ]
+    },
+    "1": {
+      "transaction_id": [
+        "value_already_exist"
+      ]
+    },
+    "2": {
+      "transaction_id": [
+        "value_already_exist"
+      ]
+    }
+  }
+}`,
+			want: &Error{
+				HTTPStatusCode: 422,
+				Message:        "Unprocessable Entity",
+				ErrorCode:      "validation_errors",
+				ErrorDetail: &ErrorDetail{
+					Multiple: true,
+					Errors: map[int]map[string][]string{
+						0: {
+							"transaction_id": {
+								"value_already_exist",
+							},
+						},
+						1: {
+							"transaction_id": {
+								"value_already_exist",
+							},
+						},
+						2: {
+							"transaction_id": {
+								"value_already_exist",
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			errObj := &Error{}
+			err := json.Unmarshal([]byte(tt.input), errObj)
+			if err != nil {
+				t.Errorf("got error %s", err.Error())
+				return
+			}
+
+			expectErr, err := json.Marshal(tt.want)
+			if err != nil {
+				t.Errorf("got error %s", err.Error())
+				return
+			}
+
+			gotErr, err := json.Marshal(errObj)
+			if err != nil {
+				t.Errorf("got error %s", err.Error())
+				return
+			}
+
+			if string(expectErr) != string(gotErr) {
+				t.Errorf("got error %s, but expected error %s", string(gotErr), string(expectErr))
+				return
+			}
+		})
+	}
+}