Unable to create an object of type 'xxContext'. Add an implementation of

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net  core 新搭建基架或操作数据库迁移时报错：

Unable to create an object of type xxContext'. Add an implementation of 'IDesignTimeDbContextFactory<xxxContext>' to the project, or see https://go.microsoft.com/fwlink/?linkid=851728 for additional patterns supported at design time.

查找相关资料，解决办法如下：

在Data文件夹，创建一个名称为：xxContextFactory 的类，类代码如下：

1. 
   
2. namespace ContosoUniversity.Data
   
3. 
   
4. {
   
5. 
   
6.     public class xxContextFactory:IDesignTimeDbContextFactory<xxContext>
   
7. 
   
8.     {
   
9. 
   
10.        // IConfiguration Configuration { get; } //使用Configuration 获取不到GetConnectionString("xxContext")。不能用
    
11. 
    
12.         public xxContext CreateDbContext(string[] args)
    
13. 
    
14.         {
    
15. 
    
16.             var optionsBuilder = new DbContextOptionsBuilder<xxContext>();
    
17. 
    
18.             //   optionsBuilder.UseSqlServer(Configuration.GetConnectionString("xxContext"));
    
19. 
    
20.             optionsBuilder.UseSqlServer("Server = (localdb)\\mssqllocaldb; Database = xxContext; Trusted_Connection = True; MultipleActiveResultSets = true");
    
21. 
    
22.             return new xxContext(optionsBuilder.Options);
    
23. 
    
24.         }
    
25. 
    
26. 
    
27. 
    
28.     }
    
29. 
    
30. }

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