如何使用EF6更新多对多表 [英] How can I use EF6 to update a many to many table
本文介绍了如何使用EF6更新多对多表的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有两个类：
公共部分类ObjectiveDetail {
公共ObjectiveDetail（）{
this.SubTopics =新的List＆LT;＆子话题GT;（）;
}
公众诠释ObjectiveDetailId {搞定;组; }
公众诠释号码{搞定;组; }
公共字符串文本{搞定;组; }
公共虚拟的ICollection＆LT;＆子话题GT;子专题{搞定;组; }
}
公共部分类子话题{
公众诠释SubTopicId {搞定;组; }
公共字符串名称{;组; }
}
我有来自用户的ObjectiveDetail对象：
VAR网络= {
objectiveDetailId：1，
1号，
文：datafromweb
副题：[
{subTopicId：1，
名：一
}，
{subTopicId：3，
名：三
}
]
}
和从数据库中ObjectiveDetail：
变种DB = {
objectiveDetailId：1，
1号，
文：datafromdb
副题：[
{subTopicId：1，
名：一
}，
{subTopicId：2，
名：两节，
}
]
}
通过实体框架6我知道我可以使用更新的ObjectiveDetail类文本：
_uow.ObjectiveDetails.Update（网络））;
但我怎么能更新到ObjectiveDetail和副主题中的多对多表联接这两个表中的引用。这里例如我希望它使得用于ObjectiveDetail 1的多对多改变为引用subTopicId 1和3的代替值1和2。注意，ObjectiveDetail和子话题存储在表中，它们之间的另一个表。这里的DDL：
CREATE TABLE [DBO]。[ObjectiveDetail]（
[ObjectiveDetailId] INT IDENTITY（1,1）NOT NULL，
【正文】NVARCHAR（MAX）NOT NULL，
[ObjectiveTopicId] INT NULL，
约束[PK_ObjectiveDetail] PRIMARY KEY CLUSTERED（[ObjectiveDetailId] ASC）
）;CREATE TABLE [DBO]。[ObjectiveTopic]（
[ObjectiveDetailId] INT NOT NULL，
[SubTopicId] INT NOT NULL，
约束[FK_ObjectiveTopicObjectiveDetail]外键（[ObjectiveDetailId]）参考文献[DBO]。[ObjectiveDetail]（[ObjectiveDetailId]），
约束[FK_ObjectiveTopicSubTopic]外键（[SubTopicId]）参考文献[DBO]。[子话题]（[SubTopicId]）
）;CREATE TABLE [DBO]。[子话题]（
[SubTopicId] INT IDENTITY（1,1）NOT NULL，
[名] NVARCHAR（150）NOT NULL，
约束[PK_SubTopic] PRIMARY KEY CLUSTERED（[SubTopicId] ASC）
）;
下面是我有EF映射：
公共类ObjectiveDetailMap：EntityTypeConfiguration＆LT; ObjectiveDetail＆GT;
{
公共ObjectiveDetailMap（）
{
// 首要的关键
this.HasKey（T =＆GT; t.ObjectiveDetailId）;
//关系
this.HasMany（T =＆GT; t.SubTopics）
.WithMany（T =＆GT; t.ObjectiveDetails）
.MAP（M =＆GT;
{
m.ToTable（ObjectiveTopic）;
m.MapLeftKey（ObjectiveDetailId）;
m.MapRightKey（SubTopicId）;
}）; }
}
解决方案
我认为你正试图模拟离线模式为用户的工作。因此，当你从你的用户的东西，你想与用户数据同步数据库。我做出了榜样，并采取了你的问题仅有一步之:)我说，需要在数据库中更新一个副主题。确定这里是code：
静态无效的主要（字串[] args）
{
//数据库
VAR ObjectiveDetails =新的List＆LT; ObjectiveDetail＆GT;（）
{
新ObjectiveDetail（）
{
ObjectiveDetailId = 1，
数= 1，
文本=datafromdb
子专题=新的List＆LT;＆子话题GT;（）
{
新的子话题（）{SubTopicId = 1，名称=一} //没有变化
新的子话题（）{SubTopicId = 2，名称=两节} //将被删除
新的子话题（）{SubTopicId = 4，名称=四个一} //进行更新
}
}
}; //对象当属JSON和序列化定义的对象。
VAR网络=新ObjectiveDetail（）
{
ObjectiveDetailId = 1，
数= 1，
文本=datafromweb
子专题=新的List＆LT;＆子话题GT;（）
{
新的子话题（）{SubTopicId = 1，名称=一} //没有变化
新的子话题（）{SubTopicId = 3，名称=三大} //新行
新的子话题（）{SubTopicId = 4，名称=新四} //必须更新
}
}; VAR objDet = ObjectiveDetails.FirstOrDefault（X =＆GT; x.ObjectiveDetailId == web.ObjectiveDetailId）;
如果（objDet！= NULL）
{
//你可以使用AutoMapper或ValueInjecter映射和绑定相同的对象
//但它超出了这个问题的范围
//更新ObjectDetail
objDet.Number = web.Number;
objDet.Text = web.Text;
变种subtops = objDet.SubTopics.ToList（）; //删除从数据库中删除参数
//实体框架可以通过更改跟踪为您处理
// subtopicId = 2已经被删除
subtops.RemoveAll（X =＆GT;！web.SubTopics.Select（Y =＆GT; y.SubTopicId）。载有（x.SubTopicId））; //添加其中来自网络新项目
//添加subtopicId = 3到列表
VAR newItems = web.SubTopics.Where（X =＆GT;！subtops.Select（Y =＆GT; y.SubTopicId）。载有（x.SubTopicId））。了ToList（）;
subtops.AddRange（newItems）; //这个项目必须更新
变种updatedItems = web.SubTopics.Except（newItems）.ToList（）; 的foreach（在updatedItems VAR项）
{
VAR dbItem = subtops.First（X =＆GT; x.SubTopicId == item.SubTopicId）;
dbItem.Name = item.Name;
} //让我们看到的是它的工作
Console.WriteLine（{0} \\ t {1} \\ t {2} \\ n ---------，objDet.ObjectiveDetailId，objDet.Number，objDet.Text）;
的foreach（在subtops VAR项）
{
Console.WriteLine（{0}：{1}，item.SubTopicId，item.Name）;
}
}
其他
{
//插入新ObjectiveDetail
} //在真实的情景所做的一切后，你需要调用的SaveChanges或者它在你的工作单位相等。
}
结果：
1：1 datafromweb
---------
1：一
4：新的四
3：三
就是这样。您可以同步你这样的数据库和用户数据。也 AutoMapper 和 ValueInjecter 都是非常有用和强大的工具，我深深建议你去看看那些。我希望你喜欢，快乐编码：）
I have two classes:
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; }
}
I have an ObjectiveDetail object from the user:
var web = {
"objectiveDetailId":1,
"number":1,
"text":"datafromweb",
"subTopics":[
{"subTopicId":1,
"name":"one"
},
{"subTopicId":3,
"name":"three",
}
]
}
And an ObjectiveDetail from the database:
var db = {
"objectiveDetailId":1,
"number":1,
"text":"datafromdb",
"subTopics":[
{"subTopicId":1,
"name":"one"
},
{"subTopicId":2,
"name":"two",
}
]
}
With Entity Framework 6 I know I can update the text in the ObjectiveDetail class using:
_uow.ObjectiveDetails.Update(web));
But how can I update the references to ObjectiveDetail and SubTopics in the many to many table that joins these two table. Here for example I would want it so that for ObjectiveDetail 1 the many-many is changed to reference subTopicId 1 and 3 instead of the values 1 and 2. Note that ObjectiveDetail and SubTopic are stored in tables with another table between them. Here's the 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, 1) NOT NULL,
[Name] NVARCHAR (150) NOT NULL,
CONSTRAINT [PK_SubTopic] PRIMARY KEY CLUSTERED ([SubTopicId] ASC),
);
Here's the EF Mapping that I have:
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");
});
}
}
解决方案
I think you are trying to simulating offline mode working for your users. So when you get something from your users, you want to sync database with user data. I make an example and take your question one step beyond :) I added a Subtopic which needs to be updated in database. Ok here is the code:
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,
Number = 1,
Text = "datafromweb",
SubTopics = new List<SubTopic>()
{
new SubTopic(){ SubTopicId = 1, Name="one"}, //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.
}
The result:
1: 1 datafromweb
---------
1: one
4: new four
3: three
That's it. You can sync your database and user data like this. And also AutoMapper and ValueInjecter both are very useful and powerful tools, I deeply recommend you to take a look at those. I hope you enjoyed, happy coding :)
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