有关如何在多个Azure SQL数据库，连接字符串和Azure App Services发布配置文件中使用迁移的完整指南

Question

I have a MVC project hosted in Azure App Services with Azure SQL databases for the data. I have a development, staging/acceptance and production environment (App Service) and as for the databases i have development, staging/acceptance, production and a local DB (mdf). I have 3 publish profiles (1 for each environment).

I (think) to understand that i can use the CTOR of the DbContext class to set a connectionstring from the web.config based on the name:

Ex.

public ApplicationDbContext(): base("DbContextNameThatResidesInWebConfig") 
{           
     // ...               
}   

If i am not using migrations i am able to do what i want without any issues. When using migrations (since i don't want any data loss when changing my model) i am getting several issues on model creation, i tried using several methods in my above CTOR:

// this is a custom Seeder that inherits DropDatabaseAlways/WhenModelChanges
System.Data.Entity.Database.SetInitializer(new ContractCareSeeder()); 

// from what i understand, this tells to use the latest migrations applied
System.Data.Entity.Database.SetInitializer(new MigrateDatabaseToLatestVersion<ApplicationDbContext, Migrations.Configuration>());

Configuration.cs:

internal sealed class Configuration : DbMigrationsConfiguration<ApplicationDbContext>
{
    public Configuration()
    {
        AutomaticMigrationsEnabled = false;
    }

    // seeding method ...
}    

But i always receive errors like, "there is already a table called XXX ..." even when i have succesfully executed the Update-Database command in the console it still fails.

I am quite lost in this and can't seem to find what is the best way of handling my scenario. I want to be able to use multiple publish profiles (later on we will use development slots but not now) and there there is also configuration possible. I can see all my connections from my web.config along with update database checkbox but i can't seem to find the right way of configuring everything together...

Can anyone assist me, suggest me or provide any help of any kind? Kind regards!

Answer 1

ASP.NET 5 introduces improved support for controlling application behavior across multiple environments , such as development , staging , and production . Environment variables are used to indicate which environment the application is running in, allowing the app to be configured appropriately.

You could set ASPNET_ENV with the current environment you want to use. If you need to check whether the application is running in a particular environment, use env.IsEnvironment("environmentname")

if (env.IsDevelopment())
{
    app.UseBrowserLink();
    app.UseDeveloperExceptionPage();
    app.UseDatabaseErrorPage();
}
else
{
    app.UseExceptionHandler("/Home/Error");
}

For more details you could refer to this article and this one which though is asp.net core.