Question

I got a form with multiple comboboxes, where each combobox can be set to different values. Based on the combobox value I want to create a query filter. I want to iterate through all comboboxes and add its value to the filter if it dont say “All”.

I want to do something like this:

    XElement root = XElement.Load(fileName);
                    IEnumerable<XElement> selectedElements =
                        from el in root.Elements("OrderNum").Elements("ServiceJob")
                        where
                            for(int i = 0; i < combArray.GetLength(0); i++)
                            {
                                if(combArray[i].Text != "All")
                                {
                                    (string)el.Element(combArray[i].AccessibleName) == combArray[i].Text &&
                                }
                            }
                        select el;

Any suggestions?

Answer 1

You can just dynamically add Where clauses as follows:

XElement root = XElement.Load(fileName);
IEnumerable<XElement> selectedElements = root.Elements("OrderNum").Elements("ServiceJob");

for(int i = 0; i < combArray.GetLength(0); i++)
{
    if(combArray[i].Text != "All")
    {
        selectedElements = selectedElements.Where(el => el.Element(combArray[i].AccessibleName) == combArray[i].Text);
    }
}

var result = selectedElements.ToList();

Each iteration of the for loop, takes the previous query and appends a suitable Where clause.

For ‘bonus points’ you can simplify your for loop using Linq:

var comboBoxes = combArray.Where(c => c.Text != "All");
foreach(var comboBox in comboBoxes)
{
    selectedElements = selectedElements.Where(el => el.Element(comboBox .AccessibleName) == comboBox .Text);
}