我来自一个Rails背景,其中@ report.update_attributes(params [:report])将确切知道如何处理它在其中找到的任何关联数据.据我所知,.NET的等价物是TryUpdateModel,看起来很有前景.首先.所以我尝试了这样的一些参数
- IDGUID:d70008a5-a1a3-03d2-7baa-e39c5044ad41
- StoredProcedureName:GetUsers
- Name:search again UPDATED
- StoredProcedureReportParameters[0].IDGUID:d70008a5-aba3-7560-a6ef-30a5524fac72
- StoredProcedureReportParameters[0].StoredProcedureReportID:d70008a5-a1a3-03d2-7baa-e39c5044ad41
- StoredProcedureReportParameters[0].Name:RowsPerPage
- StoredProcedureReportParameters[0].Label:rows
- StoredProcedureReportParameters[0].StoredProcedureReportParameterDataTypeID:a50008a5-2755-54c0-b052-865abf459f7f
- StoredProcedureReportParameters[0].StoredProcedureReportParameterInputTypeID:a50008a5-2955-a593-d00f-00cd4543babf
- StoredProcedureReportParameters[0].DefaultValue:10
- StoredProcedureReportParameters[0].AllowMultiple:false
- StoredProcedureReportParameters[0].Hidden:false
- StoredProcedureReportParameters[1].IDGUID:d70008a5-a7a3-e35e-28b6-36dd9e448ee5
- StoredProcedureReportParameters[1].StoredProcedureReportID:d70008a5-a1a3-03d2-7baa-e39c5044ad41
- StoredProcedureReportParameters[1].Name:PageNumber
- StoredProcedureReportParameters[1].Label:page was MODIFIEIIEIEIED!!!
- StoredProcedureReportParameters[1].StoredProcedureReportParameterDataTypeID:a50008a5-2755-54c0-b052-865abf459f7f
- StoredProcedureReportParameters[1].StoredProcedureReportParameterInputTypeID:a50008a5-2955-a593-d00f-00cd4543babf
- StoredProcedureReportParameters[1].DefaultValue:1
- StoredProcedureReportParameters[1].AllowMultiple:false
- StoredProcedureReportParameters[1].Hidden:false
我假设在设置了所有主键和外键后,EF会知道在执行此操作时如何更新StoredProcedureReportParameter对象:
- var report = context.StoredProcedureReports.FirstOrDefault(r => r.IDGUID == reportID);
- if (report != null)
- {
- succeeded = TryUpdateModel(report);
- context.SaveChanges();
- }
现在,如果我在context.SaveChanges()上放置断点,我的报表对象及其关联的StoredProcedureReportParameters看起来就像我期望的那样.设置外键和主键,检查所有值.但SaveChanges引发了这个错误:
The operation Failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. When a change is made to a relationship,the related foreign-key property is set to a null value. If the foreign-key does not support null values,a new relationship must be defined,the foreign-key property must be assigned another non-null value,or the unrelated object must be deleted.
此消息中的一个建议是我应该为外键属性分配一个非空值,但正如我所说,StoredProcedureReportID在两个StoredProcedureReportParameter对象上都有正确的值.
我读过的其他帖子处理Update操作循环关联并将它们附加到上下文.这真的是我坚持做的吗? EF真的那么密集吗?我希望.NET专家能够向我展示这一点.必须有一种比这更简单的方法.
解决方法
我们假设我们有2个参与者:
- public class Foo
- {
- public int FooId { get; set; }
- public string Description { get; set; }
- public ICollection<Bar> Bars { get; set; }
- }
- public class Bar
- {
- public int BarId { get; set; }
- public string Description { get; set; }
- }
INSERTING
- var foo = new Foo()
- {
- FooId = 1,Description = "as",Bars = new List<Bar>()
- {
- new Bar
- {
- BarId = 1,Description = "as"
- },new Bar
- {
- BarId = 2,Description = "as"
- }
- }
- };
- ctx.Foos.Add(foo);
- ctx.SaveChanges();
在上面的示例中,EF将识别新项目,并将插入所有项目.
更新(附件)
- var foo = ctx.Foos.Include("Bars").Where(i => i.FooId == 1).FirstOrDefault();
- foreach (var bar in foo.Bars)
- {
- bar.Description = "changed";
- }
- ctx.SaveChanges();
这里我们从上下文中加载了foo及其条形图.它们已经附在上下文中.因此,我们需要做的就是更改值并调用SaveChanges().一切都会好起来的.
更新(已分离)
- var foo = new Foo
- {
- FooId = 1,Description = "changed3",Bars = new List<Bar>
- {
- new Bar
- {
- BarId = 1,Description = "changed3"
- },Description = "changed3"
- }
- }
- };
- ctx.Entry(foo).State = EntityState.Modified;
- foreach (var bar in foo.Bars)
- {
- ctx.Entry(bar).State = EntityState.Modified;
- }
- ctx.SaveChanges();
在这里,我们正在处理数据库中已存在的项目.但是,他们没有从EF加载(他们没有附加). EF对他们一无所知.我们需要手动附加所有这些并告诉EF它们已被修改.
删除(附加)
- var foo = ctx.Foos.Include("Bars").Where(i => i.FooId == 1).FirstOrDefault();
- var bar = foo.Bars.First();
- foo.Bars.Remove(bar);
- ctx.SaveChanges();
从EF加载条,然后从集合中删除它们.
删除(已分离)
- var bar = new Bar
- {
- BarId = 1
- };
- ctx.Entry(bar).State = EntityState.Deleted;
- ctx.SaveChanges();
这里,Bar没有从上下文中加载.所以,我们必须告诉EF它被删除了.
在您的情况下,您将更新的对象发送到MVC控制器;所以,你必须告诉EF StoredProcedureReport和StoredProcedureParameters被修改.
- ctx.Entry(foo).State = EntityState.Modified;
- //remember to do the same in all children objects
它会将所有属性标记为已修改.请注意,如果未在视图上设置某些属性,则会将其更新为空值.
- context.Entry(foo).Property("Description").IsModified = true;
- context.Entry(foo).Property("AnotherProperty").IsModified = true;
希望能帮助到你!