实体框架CTP4:往哪里放SetInitializer? [英] Entity Framework CTP4: where to put SetInitializer?
问题描述
我试图添加实体框架,code首先,到已经运行与测试数据的MVC应用程序,使用CTP4 preVIEW。
I am attempting to add Entity Framework, code first, to an MVC application that's been running with test data, using the CTP4 preview.
我目前收到此错误:
的模式支持了SchedulerContext背景已经改变,因为在创建数据库。无论是手动删除/更新数据库,或拨打Database.SetInitializer与IDatabaseInitializer实例。例如,RecreateDatabaseIfModelChanges战略将自动删除并重新创建数据库,以及可选的新数据的种子吧。
我不希望在所有生成一个数据库,因为我已经有一个数据库。所以,我想加入以下的SchedulerContext构造:
I do not want to generate a database at all, as I already have a database. So I tried adding the following to the SchedulerContext constructor:
Database.SetInitializer<SchedulerContext>(new CreateDatabaseOnlyIfNotExists<SchedulerContext>());
这是没有效果可言 - 下一次它跑我得到了同样的错误。该错误似乎当执行访问数据库中的LINQ语句来发生 - 第一,我觉得
which had no effect at all -- I got the same error the next time it ran. The error seems to occur when it is executing a LINQ statement that accesses the database -- the first, I think.
我应该在哪里把这个说法,或者是这种说法的回答这个问题呢?
Where should I put this statement, or is this statement the answer to this problem at all?
推荐答案
我只是掩盖了一个事实,你已经有一个数据库和的不的要创造一个又一个......在这种情况下,答案是把它放到你的SchedulerContext类
Update
I simply glossed over the fact you already have a database and don't want to create another one...in that case the answer is to put this in your SchedulerContext class
protected override void OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder) {
modelBuilder.IncludeMetadataInDatabase = false;
}
旧的答案
您通常把它在Global.asax
Old answer
You usually put it in the Global.asax
protected void Application_Start() {
Database.SetInitializer<SchedulerContext>(new CreateDatabaseOnlyIfNotExists<SchedulerContext>());
}
请注意,它只会在第一次使用的数据上下文进行初始化。
Note that it will only be initialized on first use of the data context.
public class DataContextInitializer : CreateDatabaseOnlyIfNotExists<SchedulerContext> {
protected override void Seed(SchedulerContext context) {
}
}
然后你修改SetInitializer像这样。
Then you modify the SetInitializer like so.
System.Data.Entity.Infrastructure.Database.SetInitializer<SchedulerContext>(new DataContextInitializer());
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