EF Core Global Query Filters

Mind Map Summary

• Topic: EF Core Global Query Filters
• Definition: Predicates that are applied to all queries for a given entity type. They are defined in the OnModelCreating method of the DbContext.
• Use Cases:
  • Soft Delete: Automatically filter out entities that have been marked as deleted.
  • Multi-Tenancy: Automatically filter entities based on a tenant ID.
• Benefits:
  • Reduces Boilerplate: Eliminates the need to add the same WHERE clause to every query.
  • Improves Consistency: Ensures that the filter is applied consistently across the application.
  • Prevents Accidental Data Exposure: Helps prevent accidental exposure of soft-deleted or multi-tenant data.
• Disabling Filters: Global query filters can be disabled for a specific query using the IgnoreQueryFilters() operator.

Practice Exercise

Define a global query filter on an entity (e.g., Product) that automatically filters out any records where an IsDeleted property is true. Write a query to fetch all products and show that the deleted ones are not returned by default. Then, show how to disable the filter for a specific query.

Answer

1. Entity with IsDeleted Property:

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public bool IsDeleted { get; set; }
}

2. DbContext with Global Query Filter:

using Microsoft.EntityFrameworkCore;

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

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Product>()
            .HasQueryFilter(p => !p.IsDeleted);
    }
}

3. Querying with the Global Filter:

// This query will only return products where IsDeleted is false.
var products = context.Products.ToList();

4. Disabling the Global Filter:

// This query will return all products, including those where IsDeleted is true.
var allProducts = context.Products.IgnoreQueryFilters().ToList();