How Can Entity Framework Code First Implement Soft Delete Filtering?

Soft Delete Filtering with Entity Framework Code First

In Entity Framework Code First, soft deletion allows you to "delete" entities by marking them as deleted rather than actually removing them from the database. This is useful for scenarios where you want to prevent accidental deletion or maintain historical data.

One challenge with soft deletion is how to automatically filter out soft-deleted entities when retrieving data. This can be achieved using the EntityFramework.DynamicFilters package.

EntityFramework.DynamicFilters

EntityFramework.DynamicFilters is a library that provides a mechanism for creating global filters that are automatically applied to queries. These filters can be applied to any property of an entity, including navigation properties.

To use EntityFramework.DynamicFilters, you need to:

1. Install the package from NuGet.
2. Add the following line to your DbContext class:

public override int SaveChanges(bool acceptAllChangesOnSuccess)
{
    // Soft delete implementation here
    return base.SaveChanges(acceptAllChangesOnSuccess);
}

3. In your DbContext's OnModelCreating method, define the filter:

modelBuilder.Filter("IsDeleted", (ISoftDelete d) => d.IsDeleted, false);

This filter ensures that any query against an entity implementing the ISoftDelete interface will automatically include a WHERE clause for the IsDeleted property, excluding entities where IsDeleted is set to true.

Example

Consider the following code:

public class User : ISoftDelete
{
    public int Id { get; set; }
    public string Name { get; set; }
    public bool IsDeleted { get; set; }
}

public class DbContext : base.DbContext
{
    public DbSet<User> Users { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Filter("IsDeleted", (User u) => u.IsDeleted, false);
    }
}

With this configuration, the following code will ignore any users marked as deleted:

var user = dbContext.Users.FirstOrDefault(u => u.Id == 1);

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