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POCreating a linq expression dynamically or parsing the string value of the expression
 

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  1. POCreating a linq expression dynamically or parsing the string value of the expression
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    <p>Got an problem where I need to crate an linq expression dynamically. But I cant seem to wrap my head around it. </p> <p>So first off I got an check list box. Where I input values from a file that is selected, hence I will not know how many parameters there will be there before I run the code. Then the plan is to construct a linq sentence based on the name of the elements in the checkbox. Let me illustrate: I want to create an linq statement that looks like this: </p> <pre><code>var result = from n in data where n.Item1 == "someValueFromCheckBox" select n; </code></pre> <p>Where the data, is an tupled list like : </p> <pre><code>List&lt;Tuple&lt;string, string&gt;&gt; </code></pre> <p>And that is fine as long as the user only selects one item from the checkbox. But when the user for example selects two items, I need to create a linqu expression that looks like this: </p> <pre><code>var result = from n in data where n.Item1 == "someValueFromCheckBox" || n.Item1 == "someValueFromCheckBox1" select n; </code></pre> <p>So my first thought was to build the linq statement as a string. In the following manner: </p> <pre><code> var selectedItems = checkedListBoxSelectedTerms.CheckedItems; var linqStatement = ""; for (int i = 0; i &lt; selectedItems.Count; i++ ) { linqStatement += selectedItems[i].ToString() + "|| n.item1 ==" ; } //this is simply to remove the || "n.Item1 ==", at the end because it is not needed after the last selecteditem. linqStatement = linqStatement.Remove(linqStatement.Length - 13, 13); </code></pre> <p>But that did not work as planned, because when I put it in like this: </p> <pre><code>var result = from n in data where n.Item1 == linqStatement select n; </code></pre> <p>The whole thing becomes a string. And I cant have the "n.Item1 ==" to be a string. In theory that solution would work great for my use, because I would not have to worry about how manay elements that are in the checkbox and how many elements the user selects, but I cannot pass linqStatement whole as a string. So any help would be appriciated, because I cant seem to find an good example to do something like this. </p> <p>Thanks in advance!</p>
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