Question

I’m fairly new to C# programming and need some help.

I am trying to assign values I’ve gathered from a JSON feed to my own type, a class in which I have defined certain fields (properties) to put the JSON elements into, plus elements that are derived from a RegEx pattern matching process. This will then allow me to access the object using LINQ, as I am using a List to hold my objects.

There is a foreach loop in my code that loops for each match that my RegEx method finds. I am only interested in the parts of the JSON feed where there is a match.

So my own defined class is as such:

//simple field definition class
public class TwitterCollection
{
    public string origURL { get; set; }
    public string txtDesc { get; set; }
    public string imgURL { get; set; }
    public string userName { get; set; }
    public string createdAt { get; set; }
}

And then I want to populate List in the RegEx Matches loop:

    foreach (Match match in matches)
    {

        GroupCollection groups = match.Groups;
        var tc = new List<TwitterCollection>()
        {
            origURL = groups[0].Value.ToString(),
            txtDesc = res.text,
            imgUrl = res.profile_image_url,
            userName = res.from_user_id,
            createdAt = res.created_at,

        };
    }

The code will then go on to extract and sort the results via Linq to Objects. But compiler won’t actually let me create my var tc = new List<TwitterCollection>() because: ‘System.Collections.Generic.List’ does not contain a definition for ‘origURL’ … even though I have defined it.

It does not flag an error if I simply write new TwitterCollection but then how do I refer to this in my Linq expression later on??

Please help!

Answer 1

You need to instantiate the list outside the loop:

var list = new List<TwitterCollection>();
foreach (Match match in matches)
{

    GroupCollection groups = match.Groups;
    var tc = new TwitterCollection
    {
        origURL = groups[0].Value.ToString(),
        txtDesc = res.text,
        imgUrl = res.profile_image_url,
        userName = res.from_user_id,
        createdAt = res.created_at,
    };
    list.Add(tc);
}

At the moment, you are trying to create a new list for each element. The actual compilation error is because your object initialiser is for a TwitterCollection object, not a list of them, but there’s no point fixing that with this flaw in the logic anyway.