<c:forEach var="role" items="[entity.Role@d54d4d, entity.Role@1c61868, entity.Role@6c58db, entity.Role@13da8a5]"> <input type="checkbox" name="role_id" value=""/> </c:forEach> 在jsp中数据显示效果…

今天在运行书里的JSTL标签代码的时候出错,总结一下: 问题1.The JSP specification requires that an attribute name is preceded by whitespace 解决:<c:forEach var="book" items="${requestScope.books}"varStatus="status">出错 改为:<c:forEach var="book…

报道越短,事情越严重!文章越短,内容越精悍! 文章以efcore 2.0.0-preview2.测试验证通过.其他版本不保证使用,但是思路不会差太远.源代码 目标: 1.实现entity的自动发现和mapper设置. 2.默认字符串长度,而不是nvarchar(max). 3.decimal设置精度 4.还没做 文章的最后附efcore 所有的可替换扩展service. 实现目标1:继承RelationalModelCustomizer,重写Customize方法.当然,我们也可以重写dbcon…

错误信息: “System.Data.Entity.Core.EntityCommandExecutionException”类型的异常在 EntityFramework.SqlServer.dll 中发生,但未在用户代码中进行处理. 其他信息:执行命令定义时出错.有关详细信息,请参阅内部异常. 跟踪代码找到详细信息: Entity Framework已有打开的与此Command相关联的DataReader,必须首先将它关闭. EF内部是使用DataReader作为资料存取,所以如果没关闭连接就…

Update Entity Graph using DbContext: Updating an entity graph in disconnected scenario is a complex task. It is easy to add a new entity graph in disconnected mode, but to update an entity graph needs careful design consideration. The problem in upda…

Add Entity Graph using DbContext: Adding entity graph with all new entities is a simple task. We can use DbSet.Add() method to attach a whole entity graph to the context and set all the entity's states to Added as we have seen in theprevious section.…

Validate Entity You can write custom server side validation for any entity. To accomplish this, override ValidateEntity method of DBContext as shown below. protected override System.Data.Entity.Validation.DbEntityValidationResult ValidateEntity(DbEnt…

Colored Entity in Entity Framework 5.0 You can change the color of an entity in the designer so that it would be easy to see related groups of entities in the designer from Visual Studio 2012 onwards. To change the color of an entity, select entity i…

Create Entity Data Model: Here, we are going to create an Entity Data Model (EDM) for SchoolDB database and understand the basic building blocks. Entity Data Model is a model that describes entities and the relationships between them. Let's create fi…

Setup Entity Framework Environment: Entity Framework 5.0 API was distributed in two places, in NuGet package and in .NET framework. The .NET framework 4.0/4.5 included EF core API, whereas EntityFramework.dll via NuGet package included EF 5.0 specifi…