How to Implement Dynamic Connection Strings in Entity Framework 6 for MySQL?

Dynamic Connection Strings in Entity Framework 6 for MySQL

Background:

In Entity Framework 6, it is possible to connect to MySQL databases using the MySQL .Net Connector 6.8.1. To establish a connection, you typically provide a static connection string in the Web.config file. However, in scenarios with numerous identical schemas (e.g., one per account), dynamically generating connection strings based on account IDs is desirable.

Connecting to MySQL with Entity Framework 6

Before establishing a dynamic connection, ensure that you have configured the following settings:

• Reference the required DLLs (Mysql.Data.dll and Mysql.Data.Entity.EF6.dll) in your project.
• Add a connection string to Web.config, specifying the database name as a placeholder ("Server=localhost;Database={0};Uid=username;Pwd=password").
• In Web.config, modify the defaultConnectionFactory node to point to MySql.Data.Entity.MySqlConnectionFactory.
• Update the providers node to include the MySQL provider.

Dynamic Database Connection

To connect to a specific database dynamically, follow these steps:

• Create a helper method to generate the connection string based on the specified database name.
• Modify the ApplicationDbContext constructor to accept the database name and use the generated connection string.

Issues with Database Migrations

If you are using database migrations, you may encounter an issue where the Seed method is unable to access the database with the dynamic connection string. To resolve this:

Add a MigrationsContextFactory class that implements IDbContextFactory and returns an instance of ApplicationDbContext with a static database name (e.g., "developmentdb").

This will ensure that migrations and seed methods target the correct database even when using the dynamic connection string for other operations.

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