DefaultConnection

DefaultConnection is a conventional name used in many software projects to identify the primary database connection string. It is not a language feature but a project-wide convention, typically implemented through a configuration file and referenced by the data access layer.

In older ASP.NET templates, the connection string named DefaultConnection is stored in a configuration file such as web.config under a connectionStrings section. It is commonly used by Object Relational Mappers like Entity Framework to determine which database to connect to, often pointing to a SQL Server instance or LocalDB and including details such as the server, database name, and authentication method.

In modern ASP.NET Core applications, the same convention persists in a slightly updated form: the connection string is often placed in appsettings.json under a section such as "ConnectionStrings" with the key "DefaultConnection". The application code typically retrieves this value at startup and passes it to the ORM, for example when configuring a DbContext. While the name is commonly kept as DefaultConnection, it is not mandatory, and any other name can be used.

Over multiple environments, DefaultConnection can be overridden with environment-specific configurations to point to different databases (development, testing, production) without changing code. Careful handling of credentials and secure storage of connection strings are important, particularly for production deployments. The exact syntax and usage depend on the framework version and the chosen data access technology.