LightSwitch 2011 数据字段唯一性验证方案

LightSwitch 2011 数据字段唯一性验证方案

 

 

验证单表数据的某个字段不能输入重复值

 

设置实体字段唯一索引

如果不写代码，那么验证只会在用户提交[保存]数据后，会提示错误，很明显这样的用户体验并不好，因此还需要做以下步骤

添加自定义验证

 

partial void UserName_Validate(EntityValidationResultsBuilder results)

        {

            // results.AddPropertyError("<错误消息>");

            bool duplicateExists = false;

           

            switch (this.Details.EntityState)

            {

                case EntityState.Added:

                    {

                        //基于页面未提交数据的验证

                        duplicateExists = (from item in DataWorkspace.ApplicationData.Details.GetChanges().AddedEntities.OfType<Employee>()

                                           where item.UserName == this.UserName && !string.IsNullOrEmpty(this.UserName)

                                           select item).Count() > 1 ? true : false;

                        //基于数据库的验证

                        if (!duplicateExists)

                        duplicateExists = (from Employee emp in DataWorkspace.ApplicationData.Employees.Cast<Employee>()

                                           where this.UserName != null &&

                                           string.Compare(emp.UserName, this.UserName.Trim(), StringComparison.InvariantCultureIgnoreCase) == 0

                                           select emp).Any();

                        break;

                    }



                case EntityState.Modified:

                    {

                        duplicateExists = (from item in DataWorkspace.ApplicationData.Details.GetChanges().ModifiedEntities.OfType<Employee>()

                                           where item.UserName == this.UserName && !string.IsNullOrEmpty(this.UserName)

                                           select item).Count() > 1 ? true : false;

                        if (!duplicateExists)

                        duplicateExists = (from Employee emp in DataWorkspace.ApplicationData.Employees.Cast<Employee>()

                                           where this.UserName != null &&

                                           string.Compare(emp.UserName, this.UserName.Trim(), StringComparison.InvariantCultureIgnoreCase) == 0

                                           select emp).Any();

                        break;

                    }

            }



            if (duplicateExists)

            {

                results.AddPropertyError(string.Format("该用户[{0}]已经存在。", UserName));



            }

运行结果如下