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POSimulating Cross Context Joins--LINQ/C#
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  1. POSimulating Cross Context Joins--LINQ/C#
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    copied!<p>Here's the issue:</p> <p>I have 2 data contexts that I would like to do a join on. Now I know that LINQ doesn't allow joins from one context to another, and I know that 2 possible solutions would be to either create a single datacontext or to have 2 seperate queries (which is what I'm doing for now). However what I would like to do is to "simulate" a join.</p> <p>Here's what I've tried.</p> <pre><code>using (var _baseDataContext = Instance) { var query = from a in _baseDataContext.Account.ACCOUNTs where a.STR_ACCOUNT_NUMBER.ToString() == accountID join app in _baseDataContext.Account.APPLICATIONs on a.GUID_ACCOUNT_ID equals app.GUID_ACCOUNT join l in GetLoans() on app.GUID_APPLICATION equals l.GUID_APPLICATION select l.GUID_LOAN; return query.Count() &gt; 0 ? query.First() : Guid.Empty; } private static IQueryable&lt;LOAN&gt; GetLoans() { using (var _baseDataContext = Instance) { return (from l in _baseDataContext.Loan.LOANs select l).AsQueryable(); } } </code></pre> <p>In run time I get is </p> <p>System.InvalidOperationException: The query contains references to items defined on a different data context</p> <p>EDIT:</p> <p>Working Solution:</p> <pre><code>using (var _baseDataContext = Instance) { var query = from a in _baseDataContext.Account.ACCOUNTs where a.STR_ACCOUNT_NUMBER.ToString() == accountID join app in _baseDataContext.Account.APPLICATIONs on a.GUID_ACCOUNT_ID equals app.GUID_ACCOUNT join l in GetLoans() on app.GUID_APPLICATION equals l.GUID_APPLICATION select l.GUID_LOAN; return (query.Count() &gt; 0) ? query.First() : Guid.Empty; } private static IEnumerable&lt;LOAN&gt; GetLoans() { using (var _baseDataContext = Instance) { return (from l in _baseDataContext.Loan.LOANs select l).AsQueryable(); } } </code></pre>
 

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