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  1. PO
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    <p>You could use PredicateBuilder from <a href="http://www.albahari.com/nutshell/linqkit.aspx" rel="nofollow">LinqKit</a>. It adds some new extension methods to predicate lambdas:</p> <pre><code>var predicate = PredicateBuilder.True&lt;Customer&gt;(); if (searchingFirstName) { predicate = predicate.And(cust =&gt; cust.First == firstName); } if (searchingOrders) { // Some code to unify the .And() and .Or() cases Expression&lt;Func&lt;Order, bool&gt;&gt; subpredicate; Func&lt;Expression&lt;Func&lt;Order, bool&gt;&gt;, Expression&lt;Func&lt;Order, bool&gt;&gt;, Expression&lt;Func&lt;Order, bool&gt;&gt;&gt; joiner; if (orderMethodAny) { subpredicate = PredicateBuilder.True&lt;Order&gt;(); joiner = PredicateBuilder.And; } else { subpredicate = PredicateBuilder.False&lt;Order&gt;(); joiner = PredicateBuilder.Or; } if (searchingOrderDate) { // ... } if (searchingOrderWeight) { switch (orderOp) { case Op.Less: subpredicate = joiner(subpredicate, ord =&gt; ord.Weight &lt; orderWeight); break; case Op.LessEqual: subpredicate = joiner(subpredicate, ord =&gt; ord.Weight &lt;= orderWeight); break; case Op.Equal: subpredicate = joiner(subpredicate, ord =&gt; ord.Weight == orderWeight); break; case Op.GreaterEqual: subpredicate = joiner(subpredicate, ord =&gt; ord.Weight &gt;= orderWeight); break; case Op.Greater: subpredicate = joiner(subpredicate, ord =&gt; ord.Weight &gt; orderWeight); break; case Op.NotEqual: subpredicate = joiner(subpredicate, ord =&gt; ord.Weight != orderWeight); break; } } if (searchingOrderQuantity) { // ... } if (searchingOrderItemName) { // ... } if (searchingOrderPrice) { // ... } predicate = predicate.And(cust =&gt; cust.Orders.Any(subpredicate)); } if (searchingZipCode) { predicate = predicate.And(cust =&gt; cust.ZipCode == zipCode); } var query = Context.Customers.Where(predicate); </code></pre> <p>You might need to call <code>.Expand()</code> on the predicates before passing them as arguments, or <code>.AsExpandable()</code> on the queryable, if you are using the Entity Framework.</p>
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    1. POQuerying child tables with dynamic linq to sql?
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    1. USMarkus Jarderot
    1. USMarkus Jarderot
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    1. POQuerying child tables with dynamic linq to sql?
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    1. COThanks so much. Great answer. I had to call .Compile() on the subpredicate. predicate = predicate.And(cust => cust.Orders.Any(subpredicate.Compile()); Unfortunately I realize now my question wasn't exactly right.
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      1. USDavid
    2. CO.Compile() would convert the expression into a delegate. That would make the system do the filtering on the client instead of the database.
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      1. USMarkus Jarderot
    3. COAfter re-writing it to use real querying, I am no longer needing any Expand(), AsExpandable(), or Compile(). But its working beautifully.
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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

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