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POHow to do a Full-Text search within a Linq query when using LLBLGen
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  1. POHow to do a Full-Text search within a Linq query when using LLBLGen
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    copied!<p>[Using LLBLGen Pro 3.1 with Entity Framework 4, .NET 4 and SQLServer 2005]</p> <p>I've got a linq query that includes .Contain(keyword);</p> <pre><code> IEnumerable&lt;Product&gt; products = null; using (var context = new ModelDataContext()) { products = (from product in context.Products where product.Title.Contains(keyword) select product); } </code></pre> <p>I was looking into the performance of the query and discovered that when the SQL is generated it's actually a "like '%keyword%'" that is being generated not a contains.</p> <p>After doing a bit of research I came across some info in the LLBLGen Pro documentation regarding FunctionMapping: </p> <p><a href="http://www.llblgen.com/documentation/2.6/Using%20the%20generated%20code/Linq/gencode_linq_functionmappings.htm" rel="nofollow">http://www.llblgen.com/documentation/2.6/Using%20the%20generated%20code/Linq/gencode_linq_functionmappings.htm</a></p> <p>I've created a table-valued function on my sql database, and also the classes required within my project:</p> <pre><code> public class CustomDatabaseFunctions { public static bool FullTextSearch(string fieldToSearch, string toFind) { // empty body, as it's just here to make the query compile. The call is converted to a SQL function. return true; } } public class CustomDatabaseFunctionMappings : FunctionMappingStore { public CustomDatabaseFunctionMappings() : base() { this.Add(new FunctionMapping(typeof(CustomDatabaseFunctions),"FullTextSearch",1,"Product_FullTextSearch({0})","ProductDatabase","Resources")); } } </code></pre> <p>The next part of the documentation states that you need to pass the custom FunctionMappingStore to the LinqMetaData. In the example this is done as follows:</p> <pre><code>metaData.CustomFunctionMappings = new NorthwindFunctionMappings(); var q = from o in metaData.Order where o.CustomerId == "CHOPS" select new { o.OrderId, OrderTotal = NorthwindFunctions.CalculateOrderTotal(o.OrderId, true) }; </code></pre> <p>The problem I have is that I'm doing my linq query using the DataContext and I've no idea where the variable metaData comes from or how to use it!</p> <p>I'll keep looking to see if I can find out but any help very welcome!</p>
 

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