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POCombine two lists of entities with a condition
 

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  1. POCombine two lists of entities with a condition
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    <p>Say I have a class defined as </p> <pre><code>class Object { public int ID { get;set; } public string Property { get; set; } public override bool Equals(object obj) { Object Item = obj as Object; return Item.ID == this.ID; } public override int GetHashCode() { int hash = 13; hash = (hash * 7) + ID.GetHashCode(); return hash; } } </code></pre> <p>And two lists, defined like so:</p> <pre><code>List&lt;Object&gt; List1; List&lt;Object&gt; List2; </code></pre> <p>These two lists contain objects where <code>ID</code> fields could be the same, but <code>Property</code> fields may or may not. I want to have a result of all objects contained in <code>List1</code> together with all objects contained in <code>List2, with the condition that</code>Property<code>field must be set to</code>"1"<code>if it is set to</code>"1"` in any of those lists. The result must contain distinct values (distinct IDs).</p> <p>For example, if we have 2 lists like this:</p> <pre><code>List1 ----- ID = 0, Property = "1" ID = 1, Property = "" ID = 2, Property = "1" ID = 3, Property = "" List2 ----- ID = 1, Property = "1" ID = 2, Property = "" ID = 3, Property = "" </code></pre> <p>I need a result to look like this:</p> <pre><code>Result ------- ID = 0, Property = "1" ID = 1, Property = "1" ID = 2, Property = "1" ID = 3, Property = "" </code></pre> <p>Currently it works like this:</p> <pre><code>var Result = List1.Except(List2).Concat(List2.Except(List1)); var Intersection = List1.Intersect(List2).ToList(); Intersection.ForEach(x =&gt; { x.Property = List1.Single(y =&gt; y.ID == x.ID).Property == "1" ? "1" : List2.Single(y =&gt; y.ID == x.ID).Property == "1" ? "1" : ""; }); Result = Result.Concat(Intersection); </code></pre> <p>...but ForEach is very slow. Can someone suggest a faster way?</p>
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    1. USDejan Janjušević
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