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POC#, What's the proper syntax for calling an Expression<Func<T-in, T-out>> from within another lambda expression?
 

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  1. POC#, What's the proper syntax for calling an Expression<Func<T-in, T-out>> from within another lambda expression?
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    <p>I'm working in Entity Framework 5 and having problems creating an expression to use inside a method.</p> <p>I believe the problem is that normally I would call the expression in a lambda expression such as <code>dbContext.Counties.Select(GetLargeCities())</code>, but in the code I am working with, I am projecting the Counties entity into a view model called CountyWithCities. Where I would normally call the expression, I have a singleton <code>c</code> and don't know how to call the expression there.</p> <p>The reason I want to accomplish this using an expression is because I want the <code>GetCountiesWithCities</code> method to hit the database once, with Entity Framework constructing a complex graph for all the objects in the result.</p> <p>For some reason the code below is producing the error `The name 'GetLargeCities' does not exist in the current context."</p> <pre class="lang-cs prettyprint-override"><code> public class CountyWithCities // this is a view model { public int CountyID { get; set; } public string CountyName { get; set; } public IEnumerable&lt;City&gt; Cities { get; set; } } public class City // this is an entity { public int CityID { get; set; } public string CityName { get; set; } public int Population { get; set; } } public IEnumerable&lt;CountyWithCities&gt; GetCountiesWithCities(int StateID) { return dbContext.States .Where(s =&gt; s.StateID = StateID) .Select(s =&gt; s.Counties) .Select(c =&gt; new CountyWithCities { CountyID = c.CountyID, CountyName = c.CountyName, Cities = GetLargeCities(c) // How do I call the expression here? }); } public Expression&lt;Func&lt;County, IEnumerable&lt;City&gt;&gt;&gt; GetLargeCities = county =&gt; county.Cities.Where(city =&gt; city.Population &gt; 50000); </code></pre> <p>Thanks!</p>
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