Apply common configuration to all entity types ef core 5.0

Question

I have entities derived from a base entity in my application
Base entity:

    public abstract class Entity
    {
        public virtual int Id { get; protected set; }

        public virtual string? TenantId { get; protected set; }
    }

Derived entities:

    public class DerivedEntity : Entity
    {
         //some fields
    }

I want to apply global query filter for each entity

modelBuilder.Entity<DerivedEntity1>().HasQueryFilter(e => e.TenantId == "TenantId");
modelBuilder.Entity<DerivedEntity2>().HasQueryFilter(e => e.TenantId == "TenantId");
modelBuilder.Entity<DerivedEntity3>().HasQueryFilter(e => e.TenantId == "TenantId");

But there are many entities in the application. And can forget to apply the filter to new entities.

I would be grateful for your recommendations.

Answer 1

@Andrej , Based on your description, you want to apply common configuration to all entity types.

You can use some reflection , expression trees and IMutableModel.GetEntityTypes in your OnModelCreating method.

Like the following code

protected override void OnModelCreating(ModelBuilder modelBuilder)  
        {  
            // add your own configuration here  
  
            Expression<Func<Entity, bool>> filterExpr = bm => bm.TenantId=="TenantId";  
            foreach (var mutableEntityType in modelBuilder.Model.GetEntityTypes())  
            {  
                // check if current entity type is child of BaseModel  
                if (mutableEntityType.ClrType.IsAssignableTo(typeof(Entity)))  
                {  
                    // modify expression to handle correct child type  
                    var parameter = Expression.Parameter(mutableEntityType.ClrType);  
                    var body = ReplacingExpressionVisitor.Replace(filterExpr.Parameters.First(), parameter, filterExpr.Body);  
                    var lambdaExpression = Expression.Lambda(body, parameter);  
  
                    // set filter  
                    mutableEntityType.SetQueryFilter(lambdaExpression);  
                }  
            }  
        }  

Hope this could help you.

Best Regards,
Jack

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