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POHow can I compose an expression tree from the union of several expressions?
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copied!<p>I'm trying to construct an <code>IQueryable</code> which will be evaluated by my entity model. I want to pass it two groups of lambdas and have it compose everything into a more complex expression tree, which is passed on to the database for execution.</p> <p>Here's what I have so far:</p> <pre><code>public class FilterManager<T> { public List<Expression<Func<T, bool>>> Inclusive { get; set; } public List<Expression<Func<T, bool>>> Exclusive { get; set; } public IQueryable<T> ApplyFilters(IQueryable<T> query) { var q = query; Exclusive.ForEach(exp => q = q.Where(exp)); //works fine Inclusive.ForEach(exp => /* ??? */); return q; } //ctor, etc. } </code></pre> <p>The idea here is that I add several Expressions to <code>Inclusive</code>, which "Ors" them together. For example, if <code>T</code> is an <code>int</code>, the code:</p> <pre><code>fm.Inclusive.Add(x => x > 1); fm.Inclusive.Add(y => y < 5); query = fm.ApplyFilters(query); </code></pre> <p>should have the same result set as:</p> <pre><code>query = query.Where(z => z > 1 || z < 5); </code></pre> <p>How can I get <code>Inclusive</code> to work without third-party tools such as PredicateBuilder? Third-party tools are usually fine, but I'd like to improve my understanding of how to compose expressions in .NET.</p> <p>I also need to make sure that the tree won't be evaluated yet, so that I can do the filtering on the database. That means I'll need to produce something Entity Framework 4.0 can consume.</p>

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