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POGetting rid of outer foreach loop using linq or lambda and ensuring no duplicates are added to list
 

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  1. POGetting rid of outer foreach loop using linq or lambda and ensuring no duplicates are added to list
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    <p>I've got 2 parts to this question:</p> <ol> <li><p>Is there way to get rid of the outer loop</p> <pre><code>List&lt;Document&gt; newDocuments = new List&lt;Document&gt;(); foreach (DocumentDetail documentDetail in documentDetails) { newDocuments.AddRange(documents.FindAll(d =&gt; d.Extension.ToUpperInvariant() == documentDetail.Extension.ToUpperInvariant())); } </code></pre></li> <li><p>As you can see from the above, I'm just dealing with the "Extension" and even if I ended up keeping my outer foreach loop, I still want to check every other properties (i.e. description, etc...) so I may end up with multiple calls to the inner part and it will ended up looking like this, assuming I'm now checking Description</p> <pre><code>newDocuments.AddRange(documents.FindAll(d =&gt; d.Description.ToUpperInvariant() == documentDetail.Description.ToUpperInvariant())); </code></pre></li> </ol> <p>The problem with the above is that I could end up with duplicate documents if a document happens to have a .pdf extension and then matches the description. </p> <p>How can I ensure that no duplicates documents are added. Can I add something to my linq query (or to lambda?). In terms of uniqueness, while not definite, for now I have access to a "documentno" which is unique for all the documents held in the "documents" lists.</p> <p>If you know the answer to one part or the other, please let me know.</p> <p>Appreciated!</p> <h1>Edited</h1> <p>What about this? It definitely works, but I'm not sure this is the right way to write this?</p> <pre><code>List&lt;Document&gt; newDocs = (from documentDetail in documentDetails from document in documents where document.Extension.ToUpperInvariant() == documentDetail.Extension.ToUpperInvariant() select document).Distinct().ToList(); </code></pre> <p>Am I better off just sticking to foreach loop?</p> <p>Using the above, I would end up with something like this if I wanted to check multiple properties from the DocumentDetails list against my Document List:</p> <pre><code> List&lt;Document&gt; newDocuments = null; if (documentDetails.FindAll(dd =&gt; (dd.Extension != null || !string.IsNullOrEmpty(dd.Extension))).Count &gt; 0) { newDocuments = (from documentDetail in documentDetails from document in documents where document.Extension.ToUpperInvariant() == documentDetail.Extension.ToUpperInvariant() select document).Distinct().ToList(); } if (documentDetails.FindAll(dd =&gt; (dd.Description != null || !string.IsNullOrEmpty(dd.Description))).Count &gt; 0) { newDocuments = (from documentDetail in documentDetails from document in documents where document.Description.ToUpperInvariant() == documentDetail.Description.ToUpperInvariant() select document).Distinct().ToList(); } </code></pre> <p>While I'd still like someone to confirm that the way I wrote this is correct, I'm still left with how to append the results and then remove all duplicates. I guess when all is done, I could apply the Distinct, but I'm still left with "appending" issue. How do I do this then?</p> <p>Thanks.</p>
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