我有两个班：
public partial class ObjectiveDetail {
public ObjectiveDetail() {
this.SubTopics = new List<SubTopic>();
}
public int ObjectiveDetailId { get; set; }
public int Number { get; set; }
public string Text { get; set; }
public virtual ICollection<SubTopic> SubTopics { get; set; }
}
public partial class SubTopic {
public int SubTopicId { get; set; }
public string Name { get; set; }
}
我有一个来自用户的ObjectiveDetail对象：
var web = {
"objectiveDetailId":1,"number":1,"text":"datafromweb","subTopics":[
{"subTopicId":1,"name":"one"
},{"subTopicId":3,"name":"three",}
]
}
还有一个来自数据库的ObjectiveDetail：
var db = {
"objectiveDetailId":1,"text":"datafromdb",{"subTopicId":2,"name":"two",}
]
}
使用实体框架6我知道我可以使用以下方式更新ObjectiveDetail类中的文本：
_uow.ObjectiveDetails.Update(web));
但是,如何在多个到多个表中连接这两个表时更新对ObjectiveDetail和SubTopics的引用.这里例如我想要它,因此对于ObjectiveDetail 1,将许多数据更改为引用subTopicId 1和3而不是值1和2.注意,ObjectiveDetail和SubTopic与它们之间的另一个表存储在表中.这是DDL：
CREATE TABLE [dbo].[ObjectiveDetail] (
[ObjectiveDetailId] INT IDENTITY (1,1) NOT NULL,[Text] NVARCHAR (MAX) NOT NULL,[ObjectiveTopicId] INT NULL,CONSTRAINT [PK_ObjectiveDetail] PRIMARY KEY CLUSTERED ([ObjectiveDetailId] ASC),);
CREATE TABLE [dbo].[ObjectiveTopic] (
[ObjectiveDetailId] INT NOT NULL,[SubTopicId] INT NOT NULL,CONSTRAINT [FK_ObjectiveTopicObjectiveDetail] FOREIGN KEY ([ObjectiveDetailId]) REFERENCES [dbo].[ObjectiveDetail] ([ObjectiveDetailId]),CONSTRAINT [FK_ObjectiveTopicSubTopic] FOREIGN KEY ([SubTopicId]) REFERENCES [dbo].[SubTopic] ([SubTopicId])
);
CREATE TABLE [dbo].[SubTopic] (
[SubTopicId] INT IDENTITY (1,[Name] NVARCHAR (150) NOT NULL,CONSTRAINT [PK_SubTopic] PRIMARY KEY CLUSTERED ([SubTopicId] ASC),);
这是我有的EF Mapping：
public class ObjectiveDetailMap : EntityTypeConfiguration<ObjectiveDetail>
{
public ObjectiveDetailMap()
{
// Primary Key
this.HasKey(t => t.ObjectiveDetailId);
// Relationships
this.HasMany(t => t.SubTopics)
.WithMany(t => t.ObjectiveDetails)
.Map(m =>
{
m.ToTable("ObjectiveTopic");
m.MapLeftKey("ObjectiveDetailId");
m.MapRightKey("SubTopicId");
});
}
}
解决方法
我想您正在尝试模拟为您的用户工作的离线模式.所以当你从用户那里得到某些东西时,你想同步数据库和用户数据.我举一个例子,把你的问题从一步超越:)我添加了一个需要在数据库中更新的Subtopic.好的,这里是代码：
static void Main(string[] args)
{
//the database
var ObjectiveDetails = new List<ObjectiveDetail>()
{
new ObjectiveDetail()
{
ObjectiveDetailId = 1,Number = 1,Text = "datafromdb",SubTopics = new List<SubTopic>()
{
new SubTopic(){ SubTopicId = 1,Name="one"},//no change
new SubTopic(){ SubTopicId = 2,Name="two"},//to be deleted
new SubTopic(){ SubTopicId = 4,Name="four"} //to be updated
}
}
};
//the object comes as json and serialized to defined object.
var web = new ObjectiveDetail()
{
ObjectiveDetailId = 1,Text = "datafromweb",SubTopics = new List<SubTopic>()
{
new SubTopic(){ SubTopicId = 1,//no change
new SubTopic(){ SubTopicId = 3,Name="three"},//new row
new SubTopic(){ SubTopicId = 4,Name="new four"} //must be updated
}
};
var objDet = ObjectiveDetails.FirstOrDefault(x => x.ObjectiveDetailId == web.ObjectiveDetailId);
if (objDet != null)
{
//you can use AutoMapper or ValueInjecter for mapping and binding same objects
//but it is out of scope of this question
//update ObjectDetail
objDet.Number = web.Number;
objDet.Text = web.Text;
var subtops = objDet.SubTopics.ToList();
//Delete removed parameters from database
//Entity framework can handle it for you via change tracking
//subtopicId = 2 has been deleted
subtops.RemoveAll(x => !web.SubTopics.Select(y => y.SubTopicId).Contains(x.SubTopicId));
//adds new items which comes from web
//adds subtopicId = 3 to the list
var newItems = web.SubTopics.Where(x => !subtops.Select(y => y.SubTopicId).Contains(x.SubTopicId)).ToList();
subtops.AddRange(newItems);
//this items must be updated
var updatedItems = web.SubTopics.Except(newItems).ToList();
foreach (var item in updatedItems)
{
var dbItem = subtops.First(x => x.SubTopicId == item.SubTopicId);
dbItem.Name = item.Name;
}
//let's see is it working
Console.WriteLine("{0}:\t{1}\t{2}\n---------",objDet.ObjectiveDetailId,objDet.Number,objDet.Text);
foreach (var item in subtops)
{
Console.WriteLine("{0}: {1}",item.SubTopicId,item.Name);
}
}
else
{
//insert new ObjectiveDetail
}
//In real scenario after doing everything you need to call SaveChanges or it's equal in your Unit of Work.
}
结果：
1: 1 datafromweb --------- 1: one 4: new four 3: three
而已.您可以像这样同步您的数据库和用户数据.而且AutoMapper和ValueInjecter都是非常有用和强大的工具,我深深的推荐你来看看那些.我希望你喜欢,快乐的编码:)
