如何动态地将实体框架模型映射到表名 [英] How to map an Entity framework model to a table name dynamically
问题描述
使用代码优先的方法，我想将单个模型映射到多个表名称动态。目前，我可以像 modelBuilder.Entity（Of Person）（）。MapSingleType（）。ToTable（Managers），但作为 OnModelCreating 方法只有在我无法将其映射到其他表名时才会被调用。
在我们当前的LinqToSql版本中，我们将覆盖MetaModel.GetTable（），并返回一个新的TableAttribute与我们的动态名称。我没有在EF中找到这样的属性（即使我不知道如何覆盖它）。所以我的问题是：是否可以这样做？（/）
更新
我发现我可以通过调用
阻止 OnModelCreating 方法缓存映射modelBuilder.CacheForContextType = false;
因此，我可以为对象的实例分配表定义。这不是我想做的，但它是有效的。
更新
哦，男孩，是以上一个大错误...缓存存在一个原因！ :)所以我回到方块一个与POCO对象映射。我会发布一个更新，如果我找出一个解决方案。
最终
任何人都关心我' ve目前解决了这个问题，在这里你去：
首先我创建了一个单独的库与POCO表和一个接口
public interface IDataContext {
System.Data.Entity.DbSet< TableGeneric> TableGeneric {get;组; }
int SaveChanges（）;
}
public class TableGeneric {
[Key]
public int Column1 {get;组; }
public string Column2 {get;组; }
public DateTime Column3 {get;组; }
public string Column4 {get;组; }
public string Column5 {get;组; }
}
然后，使用CSharpCodeProvider创建了一个类，它接受以下模板和将其转换为类型定义：
class DataContext：System.Data.Entity.DbContext，IDataContext {
public System .Data.Entity.DbSet< TableGeneric> TableGeneric {get;组; }
protected override void OnModelCreating（ModelBuilder modelBuilder）{
modelBuilder
.Entity< ContextTesting.Interfaces.EF.TableGeneric（）
.MapSingleType（）
.ToTable（$ TableName $）;
}
}
使用生成的类型，我可以创建一个实例，所以这里我们去
类型typeAccountants = BuildContext.CreateGenericTable（Accountants）;
IDataContext context =（IDataContext）Activator.CreateInstance（typeAccountants）;
其余的就好像你有一个普通的DataContext。希望这有助于别人。
任何人都关心我目前如何解决这个问题，在这里你去：
首先，我创建了一个单独的库与POCO表和一个接口
public接口IDataContext {
System.Data.Entity.DbSet< TableGeneric> TableGeneric {get;组; }
int SaveChanges（）;
}
public class TableGeneric {
[Key]
public int Column1 {get;组; }
public string Column2 {get;组; }
public DateTime Column3 {get;组; }
public string Column4 {get;组; }
public string Column5 {get;组; }
}
然后，使用CSharpCodeProvider创建了一个类，它接受以下模板和将其转换为类型定义：
class DataContext：System.Data.Entity.DbContext，IDataContext {
public System .Data.Entity.DbSet< TableGeneric> TableGeneric {get;组; }
protected override void OnModelCreating（ModelBuilder modelBuilder）{
modelBuilder
.Entity< ContextTesting.Interfaces.EF.TableGeneric（）
.MapSingleType（）
.ToTable（$ TableName $）;
}
}
使用生成的类型，我可以创建一个实例，所以这里我们去
类型typeAccountants = BuildContext.CreateGenericTable（Accountants）;
IDataContext context =（IDataContext）Activator.CreateInstance（typeAccountants）;
其余的就好像你有一个普通的DataContext。希望这有助于别人。
Using a code-first approach I'd like to map a single model to multiple table names dynamically. Currently I can do something like modelBuilder.Entity(Of Person)().MapSingleType().ToTable("Managers") but as the OnModelCreating method is only called once I can't map it to other table names on the fly.
In our current LinqToSql version we're overriding the MetaModel.GetTable() and returning a new TableAttribute with our dynamic name. I haven't found an attribute like that in EF (even if there were I wouldn't know how to override that yet). So my question is: Is it possible to do this (yet)?
Update
I've found that I can prevent the OnModelCreating method from caching the mappings by calling
modelBuilder.CacheForContextType = false;
As a result I can assign table definitions on instantiation of the object. This isn't quite how I wanted to do it but it works.
Update
Oh boy, was the above a big mistake...Caching exists for a reason! :) So I'm back to square one with POCO object mapping. I'll post an update if I figure out a solution.
Final
Incase anybody cares how I've currently solved this issue, here you go:
First I created a separate library with the POCO tables and an Interface
public interface IDataContext {
System.Data.Entity.DbSet<TableGeneric> TableGeneric { get; set; }
int SaveChanges();
}
public class TableGeneric {
[Key]
public int Column1 { get; set; }
public string Column2 { get; set; }
public DateTime Column3 { get; set; }
public string Column4 { get; set; }
public string Column5 { get; set; }
}
Then, using the CSharpCodeProvider I created a class that takes the following template and turns it into a type definition:
class DataContext : System.Data.Entity.DbContext, IDataContext {
public System.Data.Entity.DbSet<TableGeneric> TableGeneric { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder) {
modelBuilder
.Entity<ContextTesting.Interfaces.EF.TableGeneric()
.MapSingleType()
.ToTable("$TableName$");
}
}
With the generated type I'm able to create an instance so here we go
Type typeAccountants = BuildContext.CreateGenericTable("Accountants");
IDataContext context = (IDataContext)Activator.CreateInstance(typeAccountants);
Then the rest is just as if you had a normal DataContext. Hope this helps someone else.
Incase anybody cares how I've currently solved this issue, here you go:
First I created a separate library with the POCO tables and an Interface
public interface IDataContext {
System.Data.Entity.DbSet<TableGeneric> TableGeneric { get; set; }
int SaveChanges();
}
public class TableGeneric {
[Key]
public int Column1 { get; set; }
public string Column2 { get; set; }
public DateTime Column3 { get; set; }
public string Column4 { get; set; }
public string Column5 { get; set; }
}
Then, using the CSharpCodeProvider I created a class that takes the following template and turns it into a type definition:
class DataContext : System.Data.Entity.DbContext, IDataContext {
public System.Data.Entity.DbSet<TableGeneric> TableGeneric { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder) {
modelBuilder
.Entity<ContextTesting.Interfaces.EF.TableGeneric()
.MapSingleType()
.ToTable("$TableName$");
}
}
With the generated type I'm able to create an instance so here we go
Type typeAccountants = BuildContext.CreateGenericTable("Accountants");
IDataContext context = (IDataContext)Activator.CreateInstance(typeAccountants);
Then the rest is just as if you had a normal DataContext. Hope this helps someone else.
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