How to Eager Load All Nested Entities in Entity Framework Core?

Eager Loading of Nested Entities with Entity Framework Core

Problem:

Eager loading all nested related entities in Entity Framework Core 2.0.1 has proven challenging. Specifically, nested entities, such as Customer and Address for an Order entity, remain null despite attempts to load them.

Attempts:

Various approaches have been attempted without success, including:

• Upgrading to EF Core 2.1 and using LazyLoadingProxies set to false.

Solution:

Currently, there is no built-in feature in EF Core for eager loading all nested related entities by default. However, there are custom extension methods that can provide this functionality:

public static IQueryable<T> Include<T>(this IQueryable<T> source, IEnumerable<string> navigationPropertyPaths)
    where T : class
{
    return navigationPropertyPaths.Aggregate(source, (query, path) => query.Include(path));
}

public static IEnumerable<string> GetIncludePaths(this DbContext context, Type clrEntityType, int maxDepth = int.MaxValue)
{
    // Omitted for brevity
}

Usage:

public virtual async Task<IEnumerable<T>> GetAllAsync(Expression<Func<T, bool>> predicate = null)
{
    var query = Context.Set<T>()
        .Include(Context.GetIncludePaths(typeof(T));

    if (predicate != null)
        query = query.Where(predicate);

    return await query.ToListAsync();
}

This usage demonstrates the inclusion of all related paths for the specified entity type.

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