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POHow to load many-to-many object graphs using Entity Framework?
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  1. POHow to load many-to-many object graphs using Entity Framework?
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    copied!<p>I have a many-to-many relationship (for this example "Left" "Right" and "Joinder") and another entity "Satellite" that keys into "Left." It just so happens that Sattelite's FK also has a unique index on it. My goal is to load one Joinder entity, along with its Left and Right entities, using properties on Satellite for a where clause.</p> <p>I've tried a number of approaches, but my vocabulary for Linq is weak and I don't even really know the terms for what I'm looking for.</p> <pre><code>var joinder = dbContext.Joinders .Include(j =&gt; j.Left) .Include(j =&gt; j.Right) .Include(j =&gt; j.Left.Satellites) .FirstOrDefault(s =&gt; s.Name == "Hubble"); </code></pre> <p>This doesn't work because the FirstOrDefault clause doesn't have context of s to analyze the name.</p> <pre><code>var joinder = dbContext.Joinders .Include(j =&gt; j.Left) .Include(j =&gt; j.Right) .Include(j =&gt; j.Left.Satellites) .Select(j =&gt; j.Left.Satellites) .Where(s =&gt; s.Name == "Hubble"); </code></pre> <p>This doesn't work because the type coming out of Select is <code>IQueryable&lt;Collection&lt;Satellite&gt;&gt;</code> which is confusing.</p> <pre><code>var query = from j in dbContext.Joinders join l in dbContext.Lefts on j.LeftId equals l.Id join r in dbContext.Rights on j.RightId equals r.Id join s in dbContext.Satellites on l.Id equals s.LeftId where s.Name == "Hubble" select j; </code></pre> <p>This query compiles and runs, but returns totally dehydrated objects to me--the Joinder reference I get back has Left and Right properties both null.</p> <pre><code>var query = from j in dbContext.Joinders join l in dbContext.Lefts on j.LeftId equals l.Id join r in dbContext.Rights on j.RightId equals r.Id join s in dbContext.Satellites on l.Id equals s.LeftId where s.Name == "Hubble" select new Joinder { Left = l, Right = r, Left.Satellites = ...? }; </code></pre> <p>This doesn't appear to work because I can't seem to dereference these property names inside an automatic initializer.</p> <p>Anyone know how to do this? Essentially I would like to search "entity framework many-to-many deep load" but I guess not everyone else would word it like me.</p>
 

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