Using 'if' statements within Linq statement

Question

So, we are trying to display information using a Linq statement yet the issue we are having is we don't want some elements to be created if a variable is "" - Currently we are unable to do this as we cannot include an 'if' statement within the linq statement. How would we get around this; the code we have is listed below.

(E.g - We don't want the 'x.Phone' element to show if it is set to "")

    Root = new RootElement ("Student Guide") {
        new Section("Contacts"){
            from x in AppDelegate.getControl.splitCategories("Contacts")
            select (Element)new RootElement(x.Title) {
                new Section(x.Title){
                    (Element)new StyledStringElement("Contact Number",x.Phone) {
                        BackgroundColor=UIColor.FromRGB(71,165,209),
                        TextColor=UIColor.White,
                        DetailColor=UIColor.White,
                    },
                }
            },
        },
    };

score 3 · Accepted Answer · answered May 01 '13 at 10:43

You could use something like:

var root = new RootElement ("Student Guide") {
    new Section("Contacts"){
        from x in AppDelegate.getControl.splitCategories("Contacts")
        let hasPhone = x.Phone == null
        select hasPhone 
         ? (Element)new RootElement(x.Title) {
             new Section(x.Title){
                 (Element)new StyledStringElement("Contact Number",x.Phone) {
                     BackgroundColor=UIColor.FromRGB(71,165,209),
                     TextColor=UIColor.White,
                     DetailColor=UIColor.White,
                 },
             }
         }
         : (Element)new RootElement(x.Title)
    },
};

Or you could break your Linq out to use a method - then it would be less copy and paste of code - e.g.

var root = new RootElement ("Student Guide") {
    new Section("Contacts"){
        from x in AppDelegate.getControl.splitCategories("Contacts")
        select Generate(x)
    },
};

with

private Element Generate(Thing x)
{
    var root = new RootElement(x.Title);
    var section  = new Section(x.Title);
    root.Add(section);

    if (x.Phone != null)
        section.Add(new StyledStringElement("Contact Number",x.Phone) {
                     BackgroundColor=UIColor.FromRGB(71,165,209),
                     TextColor=UIColor.White,
                     DetailColor=UIColor.White,
                 });

    return root;
}

score 1 · Answer 2 · answered May 01 '13 at 16:14

Maybe I'm missing something here, but AFAIK, you're just missing a where clause, no?

var root = new RootElement ("Student Guide") {
    new Section("Contacts"){
        from x in AppDelegate.getControl.splitCategories("Contacts")
        where !string.IsNullOrEmpty(x.Phone) 
        select (Element)new RootElement(x.Title) {
            new Section(x.Title){
                (Element)new StyledStringElement("Contact Number",x.Phone) {
                    BackgroundColor=UIColor.FromRGB(71,165,209),
                    TextColor=UIColor.White,
                    DetailColor=UIColor.White,
                },
            }
        },
    },
};

score 0 · Answer 3 · answered May 01 '13 at 08:41

0

Potentially use a conditional operator?

string.IsNullOrEmpty(x.Phone) ? "Return Something if it is empty" : x.Phone;

http://msdn.microsoft.com/en-us/library/ty67wk28(v=vs.80).aspx

answered May 01 '13 at 08:41

LukeHennerley

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Though, how would I use this to create a new 'StyledStringElement' if it is not NullOrEmpty? I have attempted this myself yet cannot figure it out as of yet. – Christopher Orchard May 01 '13 at 08:49
@LoadData Why not just pass an empty string? I don't know what `StyledSTringElement` is :P – LukeHennerley May 01 '13 at 09:20
Because we need it as a StyledStringElement to display the text in the format we want - The reason I don't know how else we can do this. – Christopher Orchard May 01 '13 at 09:42

Using 'if' statements within Linq statement

3 Answers3