feat: add IsDocumentExists function

Author: miilord

utils.go

@@ -14,6 +14,34 @@ func GetPointer[T any](value T) *T {
 	return &value
 }
 
+// IsDocumentExists checks if a MongoDB FindOne/Find operation returned an error indicating
+// the absence of documents. It returns true if documents are found, false if
+// no documents are found, and any other error encountered during the operation.
+// The function is designed to be used in conjunction with MongoDB FindOne/Find queries.
+// Example:
+//
+//	_, err := db.Mongo.Account.FindOne(context.TODO(), filter)
+//	exists, err := IsDocumentExists(err)
+//	if err != nil {
+//	    return err
+//	}
+//	if !exists {
+//	    return fmt.Errorf("Document not found")
+//	}
+func IsDocumentExists(err error) (bool, error) {
+	// if err == mongo.ErrNoDocuments {
+	// 	err = nil
+	// }
+	// return err == nil, err
+	if err == nil {
+		return true, nil
+	}
+	if err == mongo.ErrNoDocuments {
+		return false, nil
+	}
+	return false, err
+}
+
 // Generate index models from unique and compound index definitions.
 // If uniques/indexes is []string{"name"}, means create index "name"
 // If uniques/indexes is []string{"name,-age","uid"}, means create compound indexes: name and -age, then create one index: uid

utils_test.go

@@ -1,6 +1,7 @@
 package modm
 
 import (
+	"errors"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -17,6 +18,36 @@ func TestGetPointer(t *testing.T) {
 	assert.Equal(t, value, *ptr)
 }
 
+func TestIsDocumentExists(t *testing.T) {
+	// Case 1: Error is nil
+	exists, err := IsDocumentExists(nil)
+	if err != nil {
+		t.Errorf("Expected nil error, got %v", err)
+	}
+	if !exists {
+		t.Error("Expected true, got false")
+	}
+
+	// Case 2: Error is mongo.ErrNoDocuments
+	exists, err = IsDocumentExists(mongo.ErrNoDocuments)
+	if err != nil {
+		t.Errorf("Expected nil error, got %v", err)
+	}
+	if exists {
+		t.Error("Expected false, got true")
+	}
+
+	// Case 3: Other error
+	otherError := errors.New("some other error")
+	exists, err = IsDocumentExists(otherError)
+	if err != otherError {
+		t.Errorf("Expected %v error, got %v", otherError, err)
+	}
+	if exists {
+		t.Error("Expected false, got true")
+	}
+}
+
 func TestIndexesToModel(t *testing.T) {
 	uniques := []string{"name", "uid"}
 	indexes := []string{"name,-age", "email"}