Handle database errors easily when working with Entity Framework Core. Supports SQLServer, PostgreSQL, SQLite, Oracle and MySql

When using Entity Framework Core for data access all database exceptions are wrapped in DbUpdateException. If you need to find whether the exception was caused by a unique constraint, value being too long or value missing for a required column you need to dig into the concrete DbException subclass instance and check the error code to determine the exact cause.

EntityFramework.Exceptions simplifies this by handling all the database specific details and throwing different exceptions. All you have to do is to configure DbContext by calling UseExceptionProcessor and handle the exception(s) such as UniqueConstraintException, CannotInsertNullException, MaxLengthExceededException, NumericOverflowException, ReferenceConstraintException you need.

First, install the package corresponding to your database:

PM> Install-Package EntityFrameworkCore.Exceptions.SqlServer

PM> Install-Package EntityFrameworkCore.Exceptions.MySql

PM> Install-Package EntityFrameworkCore.Exceptions.MySql.Pomelo

PM> Install-Package EntityFrameworkCore.Exceptions.PostgreSQL

PM> Install-Package EntityFrameworkCore.Exceptions.Sqlite

PM> Install-Package EntityFrameworkCore.Exceptions.Oracle

Or:

dotnet add package EntityFrameworkCore.Exceptions.SqlServer

dotnet add package EntityFrameworkCore.Exceptions.MySql

dotnet add package EntityFrameworkCore.Exceptions.MySql.Pomelo

dotnet add package EntityFrameworkCore.Exceptions.PostgreSQL

dotnet add package EntityFrameworkCore.Exceptions.Sqlite

dotnet add package EntityFrameworkCore.Exceptions.Oracle

Next, in your DbContext OnConfiguring method call UseExceptionProcessor extension method:

class DemoContext : DbContext
{
    public DbSet<Product> Products { get; set; }
    public DbSet<ProductSale> ProductSale { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseExceptionProcessor();
    }
}

You will now start getting different exception for different database error. For example, when a unique constraints fails you will get UniqueConstraintException exception:

using (var demoContext = new DemoContext())
{
    demoContext.Products.Add(new Product
    {
        Name = "a",
        Price = 1
    });

    demoContext.Products.Add(new Product
    {
        Name = "a",
        Price = 1
    });

    try
    {
        demoContext.SaveChanges();
    }
    catch (UniqueConstraintException e)
    {
        //Handle exception here
    }
}