EF Core: Dynamic HasQueryFilter

Question

For a particular use case I need to apply a global query filter for my entities without using generic.

My entities cannot implement any interface, however they have a filed named "CustomFiled". All things I need is apply a filter for CustomFiled property where its value it's not null.

Something like following:

modelBuilder.Entity(entity.ClrType).HasQueryFilter("CustomFiled != null");

Is there any way?

Answer 1

Yes there is, basically it will be a variation of this answer but using a bit more of reflection instead of expression trees. At the end of the OnModelCreating method add something like the following:

foreach (var mutableEntityType in modelBuilder.Model.GetEntityTypes())
{
    // check if current entity type has corresponding property 
    var propertyInfo = mutableEntityType.ClrType.GetProperty("CustomFiled");

    if (propertyInfo is not null)
    {
        // check it type can be assigned null
        var type = propertyInfo.PropertyType;
        if (type.IsValueType && Nullable.GetUnderlyingType(type) == null)
        {
            continue;
        }

        // create filter expression
        var parameter = Expression.Parameter(mutableEntityType.ClrType);
        var body = Expression.NotEqual(
            Expression.Property(parameter, propertyInfo),
            Expression.Constant(null, type));
        var lambdaExpression = Expression.Lambda(body, parameter);
        lambdaExpression.Compile();

        // set filter
        mutableEntityType.SetQueryFilter(lambdaExpression);
    }
}