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    <p>Assuming that a Group can have Messages and a Message can have Groups, you are trying to maintain 5 things:</p> <ol> <li>The list of all Groups <code>List&lt;Group&gt; Groups = ...</code></li> <li>The list of all Messages <code>List&lt;Message&gt; messages = ...</code></li> <li>The messages for each Group <code>List&lt;Message&gt; GroupMessages...</code> in Group</li> <li>The groups for each message <code>List&lt;Group&gt; MessageGroup...</code> in Message</li> <li>The actual message to send to the group updated in several places</li> </ol> <p>From what I can see it's the last one that is not being maintained correctly:</p> <ul> <li><p>In <code>AddMessagetoGroup</code> you associate a 'new' <code>Message</code> to the <code>Group.GroupMessages</code>. This is a new instance of a class and won't be updated automatically when you update other Message instances. Just because two messages have the same <code>MessageId</code> doesn't mean they are the same instance.</p></li> <li><p>In <code>UpdateMessage</code> you change a particular message but only in the messages list. This doesn't point to the same message in the group list.</p></li> </ul> <p>All in all, you need a refactor to really get your code to what you want it to do. The way I see it is that you want to keep groups and messages separate, and reference once from the other rather than create copies. </p> <p>First, the master list:</p> <pre><code>List&lt;Group&gt; Groups = new List&lt;Group&gt;(); List&lt;Message&gt; Messages = new List&lt;Message&gt;(); </code></pre> <p>Secondly, creating <strong>or</strong> updating a message (you don't have the create part yet):</p> <pre><code>public Message CreateOrUpdateMessage(string messageID, string groupMessage) { var findmessage = Messages.Where(s =&gt; s.MessageID == messageID).FirstOrDefault(); if (findmessage != null) { findmessage.GroupMessage = groupMessage; } else { findmessage = new Message() { MessageID = messageID, GroupMessage = groupMessage}; Messages.Add(findmessage); } return findmessage; } </code></pre> <p>Note how this takes care of adding this message to the Messages list. This is the only function that should add or change messages.</p> <p>And finally adding messages to a group (note I don't worry about adding groups here):</p> <pre><code>public void AddMessagetoGroup(string group, string messageID, string message) { var findmessage = CreateOrUpdateMessage(messageID, message); var findgroup = Groups.Where(n =&gt; String.Equals(n.GroupName, group)).FirstOrDefault(); if (findgroup != null) { if (findgroup.GroupMessages.Where(m =&gt; m.MessageID == messageID).Count() == 0) { findgroup.GroupMessages.Add(findmessage); findmessage.MessageGroup.Add(findgroup); } } } </code></pre> <p>Note that this function will also create the message, and ensure there are no duplicates in either Messages in total or Messages for any particular group.</p>
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    1. POlinq issue with creating relationships
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    1. USyamen
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    1. COArgh so confusing (not your answer) thought I was on the right track, it may take me a while to implement and test what you said. So I am going to thank you in advance and get to work on refactoring my code. +1 Yamen for understanding and a very clear and concise answer.
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      1. USGarrith Graham
    2. COHmm something really strange is going on using the above, The underlying connection was closed: An unexpected error occurred on a receive. Any time I try to list groups, messages?
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      1. USGarrith Graham
    3. COThis doesn't seem to have anything to do with code we can see - likely you're using LINQ connected to an underlying source, and the delayed execution is causing issues. What is the configuration? Perhaps worth a different question.
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