Return an array with LINQ to SQL query

Question

I want to return an array to my WP 8 page and have an error: not all code paths return a value. How can I correct it? My WCF service has the following code:

public Point getAllusrs (int myID)
    {
        DataClasses1DataContext data = new DataClasses1DataContext();
        var a = (from s in data.Tabs where s.u1ID == myID && s.status == true select s.u2ID).ToArray();
        int inc = 0;

        foreach (var d in data.Users)
        {
            if (a[inc] != null && d.Id == a[inc])
            {
                inc++;
                return new Point() { Lat = d.usrLat, Lon = d.usrLong };
            }
            else inc++;
        }       
    }

Do you actually want to return an array of Point or a single Point? — Dave Zych
– Dave Zych, Commented Jul 25, 2014 at 17:10
@Dave, array of Point to create multiple pushpins on the map. — Peter
– Peter, Commented Jul 25, 2014 at 17:18

AndreyAkinshin · Accepted Answer · 2014-07-25 17:08:49Z

You must handle the case, when there is no user with target Id.

For example, you can return default value in the end of the method:

public Point getAllusrs (int myID)
{
    DataClasses1DataContext data = new DataClasses1DataContext();
    var a = (from s in data.Tabs where s.u1ID == myID && s.status == true select s.u2ID).ToArray();
    int inc = 0;

    foreach (var d in data.Users)
    {
        if (a[inc] != null && d.Id == a[inc])
        {
            inc++;
            return new Point() { Lat = d.usrLat, Lon = d.usrLong };
        }
        else inc++;
    }       
    return default(Point); // or some Point with default Lat and Lon
}

or throw some exception:

public Point getAllusrs (int myID)
{
    DataClasses1DataContext data = new DataClasses1DataContext();
    var a = (from s in data.Tabs where s.u1ID == myID && s.status == true select s.u2ID).ToArray();
    int inc = 0;

    foreach (var d in data.Users)
    {
        if (a[inc] != null && d.Id == a[inc])
        {
            inc++;
            return new Point() { Lat = d.usrLat, Lon = d.usrLong };
        }
        else inc++;
    }       
    throw new Exception("Point not found"); // or some custom Exception
}

Dennis R · Accepted Answer · 2014-07-25 17:02:59Z

0

It's because if the code doesn't satisfy the condition it doesn't return any value.

public Point getAllusrs (int myID)
{
    Point pnt = null; // or new Point ();
    DataClasses1DataContext data = new DataClasses1DataContext();
    var a = (from s in data.Tabs where s.u1ID == myID && s.status == true select s.u2ID).ToArray();
    int inc = 0;

    foreach (var d in data.Users)
    {
        if (a[inc] != null && d.Id == a[inc])
        {
            inc++;
            pnt = new Point() { Lat = d.usrLat, Lon = d.usrLong };
        }
        else inc++;
    }  

    return pnt;   
}

answered Jul 25, 2014 at 17:02

Dennis R

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