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copied!<p>Replace</p> <p><code>public virtual List<Wheel> Wheels { get; set; }</code></p> <p>with</p> <p><code>public virtual ICollection<Wheel> Wheels { get; set; }</code></p> <p>This way EntityFramework will understand this as a Lazy-loaded child list and won't populate with values until needed.</p> <p>By using LinqToEntities, you can retrieve only the keys into a new list, like:</p> <pre><code>public virtual List<int> WheelIDs { get { return Wheels.Select(_w => _w.Id).ToList(); } } </code></pre> <p>This won't load the Wheels list but will return only their ID's for your.</p> <p>Remember that this is just a guess. You're needs might change, you might need to avoid DB hit everytime to check for wheels ID's and all, but this should help you find your way.</p> <h3>EDIT: some code to show better usage of IQueryable here...</h3> <pre><code>{ using(var context = new MyContext()) { // Doing this the wheel collection WON'T GET LOADED var cars = context.Cars; } using(var context = new MyContext()) { // Doing this the wheel collection WILL get loaded var cars = context.Cars.Include(_c => _c.Wheels); } using(var context = new MyContext()) { // Doing this also gets the wheel collection loaded // But this time, it will retrieve wheel-by-wheel on each loop. var cars = context.Cars; foreach(var car in cars) { foreach(var wheel in wheels) { /* do something */ } } } using (var context = new MyContext()) { // Doing this will get your id's without loading the entire wheel collection var cars = context.Cars; var wheelsIDs = cars.Wheels.Select(_w => _w.Id).ToList(); } using (var context = new MyContext()) { // Doing this will return every wheel for your car. // This improves performance over the other that retrieves wheel-by-wheel. var cars = context.Cars; foreach(var car in cars) { var wheels = car.Wheels.ToList(); } } } </code></pre>

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