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    <p><em>Disclaimer: I'm fairly new to this and there is probably much better ways to do this. Any feedback is higlhy appreciated.</em></p> <p>Note that this method has no error/null checking. Since it uses reflection, you should profile it if you plan to use it in production.</p> <pre><code>public static IEnumerable&lt;T&gt; Filter&lt;T&gt;(IEnumerable&lt;T&gt; collection, Dictionary&lt;string, object&gt; filters) { var type = typeof (T); var properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance); var queryable = collection.AsQueryable(); var instance = Expression.Parameter(type, "instance"); var expressions = new Stack&lt;Expression&gt;(); foreach (var filter in filters) { var propertyName = filter.Key; var property = properties.FirstOrDefault(x =&gt; x.Name == propertyName); if (property == null) continue; var left = Expression.Property(instance, property); var right = Expression.Constant(filter.Value, property.PropertyType); var expr = Expression.Equal(left, right); expressions.Push(expr); } Expression call = null; Expression previousExpression = null; while(expressions.Count &gt; 0) { var expr = expressions.Pop(); if(previousExpression == null) { previousExpression = expr; call = expr; } else { var and = Expression.AndAlso(previousExpression, expr); call = and; previousExpression = and; } } var whereCallExpression = Expression.Call( typeof(Queryable), "Where", new[] { queryable.ElementType }, queryable.Expression, Expression.Lambda&lt;Func&lt;T, bool&gt;&gt;(call, new[] { instance })); return queryable.Provider.CreateQuery&lt;T&gt;(whereCallExpression); } </code></pre> <p>It overates all filters and tries to find a matching property. If it does find a property, it creates a EqualExpression which compares the actual value and the value you want to filter by. It then creates a <code>MethodCallExpression</code> which is passed to the query provider.</p> <p>Theese expressions are then combined. I think the part with the stack is wrong, and that there is a better way to do it.</p> <p>Usage:</p> <pre><code>var persons = new List&lt;Person&gt; {new Person {Name = "Alex", Age = 22}, new Person {Name = "Jesper", Age = 30}}; var filters = new Dictionary&lt;string, object&gt;(); filters.Add("Name", "Alexander Nyquist"); var results = Filter(persons, filters); </code></pre> <p>Since it's building expressions, it does works with Linq 2 Sql (tested) and probably Entity Framework. Linq 2 sql produces the following query:</p> <pre><code>SELECT [t0].[Id], [t0].[Name], [t0].[Email] FROM [dbo].[Persons] AS [t0] WHERE [t0].[Name] = @p0 -- @p0: Input VarChar (Size = 8000; Prec = 0; Scale = 0) [Alexander Nyquist] -- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1 </code></pre> <p>Hope this helps.</p>
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