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POLINQ Expression to return Property value?
 

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    <p>I'm trying to create a generic function to help me select thousands of records using LINQ to SQL from a local list. SQL Server (2005 at least) limits queries to 2100 parameters and I'd like to select more records than that.</p> <p>Here would be a good example usage:</p> <pre><code>var some_product_numbers = new int[] { 1,2,3 ... 9999 }; Products.SelectByParameterList(some_product_numbers, p =&gt; p.ProductNumber); </code></pre> <p>Here is my (non-working) implementation:</p> <pre><code>public static IEnumerable&lt;T&gt; SelectByParameterList&lt;T, PropertyType&gt;(Table&lt;T&gt; items, IEnumerable&lt;PropertyType&gt; parameterList, Expression&lt;Func&lt;T, PropertyType&gt;&gt; property) where T : class { var groups = parameterList .Select((Parameter, index) =&gt; new { GroupID = index / 2000, //2000 parameters per request Parameter } ) .GroupBy(x =&gt; x.GroupID) .AsEnumerable(); var results = groups .Select(g =&gt; new { Group = g, Parameters = g.Select(x =&gt; x.Parameter) } ) .SelectMany(g =&gt; /* THIS PART FAILS MISERABLY */ items.Where(item =&gt; g.Parameters.Contains(property.Compile()(item))) ); return results; } </code></pre> <p>I have seen plenty of examples of building predicates using expressions. In this case I only want to execute the delegate to return the value of the current ProductNumber. Or rather, I want to translate this into the SQL query (it works fine in non-generic form).</p> <p>I know that compiling the Expression just takes me back to square one (passing in the delegate as Func) but I'm unsure of how to pass a parameter to an "uncompiled" expression.</p> <p>Thanks for your help!</p> <p>**** EDIT:** Let me clarify further:</p> <p>Here is a working example of what I want to generalize:</p> <pre><code>var local_refill_ids = Refills.Select(r =&gt; r.Id).Take(20).ToArray(); var groups = local_refill_ids .Select((Parameter, index) =&gt; new { GroupID = index / 5, //5 parameters per request Parameter } ) .GroupBy(x =&gt; x.GroupID) .AsEnumerable(); var results = groups .Select(g =&gt; new { Group = g, Parameters = g.Select(x =&gt; x.Parameter) } ) .SelectMany(g =&gt; Refills.Where(r =&gt; g.Parameters.Contains(r.Id)) ) .ToArray() ; </code></pre> <p>Results in this SQL code:</p> <pre><code>SELECT [t0].[Id], ... [t0].[Version] FROM [Refill] AS [t0] WHERE [t0].[Id] IN (@p0, @p1, @p2, @p3, @p4) ... That query 4 more times (20 / 5 = 4) </code></pre>
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