Added BeforeSave

models/gencloud.go

@@ -192,7 +192,7 @@ type UsersQuery struct {
 }
 
 type GCUser struct {
-	Id            string `json:"id" gorm:"primaryKey;foreignKey"`
+	Id            string `json:"id" gorm:"primaryKey"`
 	Name          string `json:"name"`
 	Email         string `json:"email"`
 	State         string `json:"state"`

models/participant.go

@@ -2,6 +2,8 @@ package models
 
 import (
 	"time"
+
+	"gorm.io/gorm"
 )
 
 type DBParticipant struct {
@@ -30,3 +32,11 @@ type DBParticipant struct {
 func (DBParticipant) TableName() string {
 	return "gc_participants"
 }
+
+func (p *DBParticipant) BeforeSave(tx *gorm.DB) error {
+	// Convert empty string to nil
+	if p.UserId != nil && *p.UserId == "" {
+		p.UserId = nil
+	}
+	return nil
+}