Entity framework code first migration to multiple database

Question

Entity framework code first migration to multiple database

code-first ef-code-first ef-migrations entity-framework entity-framework-6

Question

Lets say we have the architecture model of web application where we have 1 database per 1 account. Database structure is the same for these accounts and differs only on data with in. How can i configurate a migrations in code first model.

Vitach

Popular Answer

In addition to your excellent answer, you can use an external config file (i.e. "clients.json") instead of hardcoding them, put all the database infos in key-value pairs into the json file and load it during startup.

Then, by iterating over the key-value pairs, you can do the initialization.

The clients.json:

{
  "DatabaseA": "DatabaseAConnectionString",
  "DatabaseB": "DatabaseBConnectionString",
  "DatabaseC": "DatabaseCConnectionString",
  ...
}

Provide a method to handle the migrations:

public static void MigrateDatabases(IDictionary<string,string> databaseConfigs)
{
  foreach (var db in databaseConfigs)
  {
    var config = new Configuration
    {
      TargetDatabase = new DbConnectionInfo(db.Value, "System.Data.SqlClient")
    };

    var migrator = new DbMigrator(config);
    migrator.Update();
  }
}

Then during startup, (I use OWIN, so it's in my Startup.cs, could also be global.asax.cs):

string json;
var path = HttpRuntime.AppDomainAppPath;
using (var reader = new StreamReader(path + @"Config\clients.json"))
{
   json = reader.ReadToEnd();
}

var databases = JsonConvert.DeserializeObject<IDictionary<string, string>>(json);
MigrateDatabases(databases);

Works like a charm for me :)

maxmantz

View more on Stack Overflow

Vitach · Accepted Answer · 1/7/2014 6:27:16 AM

Now I have next solution. In the main method or in global.asax something like this:

    var migration_config = new Configuration();
    migration_config.TargetDatabase = new DbConnectionInfo("BlogContext");
    var migrator = new DbMigrator(migration_config);
    migrator.Update();
    migration_config.TargetDatabase = new DbConnectionInfo("BlogContextCopy");
    migrator = new DbMigrator(migration_config);
    migrator.Update();

Connection strings for example in app_config file:

<connectionStrings>
 <add name="BlogContext" providerName="System.Data.SqlClient" connectionString="Server=(localdb)\v11.0;Database=MigrationsDemo.BlogContext;Integrated Security=True;"/>
 <add name="BlogContextCopy" providerName="System.Data.SqlClient" connectionString="Server=(localdb)\v11.0;Database=MigrationsDemo.BlogContextCopy;Integrated Security=True;"/>
</connectionStrings>

Configuration class and context:

internal sealed class Configuration : DbMigrationsConfiguration<MigrationsDemo.BlogContext>
{
    public Configuration()
    {
        AutomaticMigrationsEnabled = true;
        AutomaticMigrationDataLossAllowed = true;
    }

    protected override void Seed(MigrationsDemo.BlogContext context) {
    }
}

public class BlogContext : DbContext {
    public BlogContext() {}
    public BlogContext(string connection_name) : base(connection_name) {
    }
    public DbSet<Blog> Blogs { get; set; }
}

Entity framework code first migration to multiple database

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