Does not help with implementing basic OOP

[DimitryNechaev]

This article implies that if I have 10 entities which have the same field "IsDeleted" I need to copy-paste the filter 10 times.
Basic OOP expects to have a single base entity with the field and the rule applied on the base level.

At the moment I greatly struggle with EF Core trying to do exactly this and nowhere can find applicable article.
In my case a large number of 3rd pty tables having StatusId field, which I mage though basic abstract class HasStatus.

The best so far is that I manage to enumarate though all entities but can't apply a filter, as there is no generic to accept the base type. HasQueryFilter accepts LambdaExpression, which is a bummer.

        foreach (var entity in modelBuilder.Model.FindLeastDerivedEntityTypes(typeof(HasStatus)))
        {
            modelBuilder.Entity(entity.ClrType)
                .HasQueryFilter(t => t.StatusID == 1);
       }

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Document Details

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• ID: b7c9bd3e-4b99-9acf-48d8-e47bc53eb54e
• Version Independent ID: 220e0a6c-d227-956a-d27a-7c88804f770c
• Content: Global Query Filters - EF Core
• Content Source: entity-framework/core/querying/filters.md
• Product: entity-framework
• Technology: entity-framework-core
• GitHub Login: @maumar
• Microsoft Alias: avickers

[ajcvickers]

@DimitryNechaev This is one of the usability issues around query filters that are being tracked on dotnet/efcore#21459. Closing this as a duplicate of that issue, with a reference to here.

[stevendarby]

FWIW you can build the expression doing something like so:

foreach (var entity in modelBuilder.Model.FindLeastDerivedEntityTypes(typeof(HasStatus)))
{
    var statusIdProperty = entity.FindProperty(nameof(HasStatus.StatusID)).PropertyInfo;
  
    var parameterExpression = Expression.Parameter(entity.ClrType);
    var propertyExpression = Expression.Property(parameterExpression, statusIdProperty);
    var constExpression = Expression.Constant(1);

    var equalExpression = Expression.Equal(propertyExpression, constExpression));
    
    var filter = Expression.Lambda(equalExpression, parameterExpression);

    modelBuilder.Entity(entity.ClrType).HasQueryFilter(filter);
}